MEMBRANE STRUCTURE AND FUNCTION

MEMBRANE STRUCTURE AND FUNCTION
تركيب الغشاء ووظيفته Copyright © 2009 Pearson Education, Inc.

Membranes are composed of phospholipids and proteins
5.1 Membranes are a fluid mosaic of phospholipids and proteins الأغشية عبارة عن فسيفيساء مائع مكون من لبيدات فسفورية وبروتينات Membranes are composed of phospholipids and proteins تتألف الأغشية من لبيدات فسفورية وبروتينات Many phospholipids are made from unsaturated fatty acids that have kinks in their tails تصنع معظم اللبيدات الفوسفورية من أحماض دهنية غير مشبعة ذات انحنائات في ذيولها Membranes are commonly described as a fluid mosaic توصف عادة الأغشية بالفسيفساء المائع This means that the surface appears mosaic because of the proteins embedded in the phospholipids and fluid because the proteins can drift about in the phospholipids يعني ذلك أن السطح يظهر مزركشاً بسبب البروتينات المطمورة في اللبيدات الفسفورية ، و مائع لتجول البروتينات من مكان لآخر في الليبيدات الفسفورية This is aided by cholesterol wedged into the bilayer to help keep it liquid at lower temperatures كما يساعد الكوليسترول المحشور في طبقتي اللبيد الفسفوري على الاحتفاظ بهذه الميوعة في درجات الحرارة منخفضة The structure of the membrane is described as a fluid mosaic model. Scientists propose models as hypotheses, which are ways of explaining existing information. Sometimes models are replaced with an updated version. Models inspire experiments, and few models survive these tests without modifications. The fluid mosaic model is being continually refined. You may want to mention to your students that because of the hydrophobic properties of the tail of phospholipids, lipid bilayers are naturally self-healing. Teaching Tips 1. You might wish to share a very simple analogy that seems to work well for some students. A cell membrane is a little like a peanut butter and jelly sandwich with jellybeans poked into it. The bread represents the hydrophilic portions of the bilayer (and bread does indeed quickly absorb water). The peanut butter and jelly represent the hydrophobic regions (and peanut butter, containing plenty of oil, is generally hydrophobic). The jellybeans stuck into the sandwich represent proteins variously embedded partially into or completely through the membrane. Transport proteins would be like the jellybeans that poke completely through the sandwich. Analogies are rarely perfect. Challenge your students to critique this analogy by finding exceptions. (For example, this analogy does not include a model of the carbohydrates on the cell surface.) Copyright © 2009 Pearson Education, Inc.

Phospholipid bilayer (cross section) طبقتي اللبيد الفسفوري (قطاع عرضي)
طبقتي اللبيد الفوسفوري Hydrophobic regions of protein مناطق كره الماء في البروتين Hydrophilic regions of protein مناطق حب الماء في البروتين Kink انحناء Hydrophilic head رأس محب للماء WATER ماء Hydrophobic tail ذيل كاره للماء Campbell, Neil, and Jane Reece, Biology, 8th ed., Figure 7.3 The fluid mosaic model for membranes. Phospholipid bilayer (cross section) طبقتي اللبيد الفسفوري (قطاع عرضي) The fluid mosaic model for membranes نموذج الفسيفيساء المائع للأغشية

5.1 Membranes are a fluid mosaic of phospholipids and proteins الأغشية عبارة عن فسيفيساء مائع مكون من لبيدات فسفورية وبروتينات Many membrane proteins function as enzymes, others in signal transduction, while others are important in transport تعمل الكثير من بروتينات الغشاء كإنزيمات بينما يعمل البعض الآخر في النقل الإشاري والبعض هام في النقل الخلوي Because membranes allow some substances to cross or be transported more easily than others, they exhibit selectively permeability تبدي الأغشية خاصية النفاذ التفاضلية وذلك بسماحها بسهولة مرور ونقل بعض المواد فضلاً عن غيرها Nonpolar molecules (carbon dioxide and oxygen) cross easily تعبر الجزيئات غير القطبية (ثاني أوكسيد الكربون والأوكسجسن) بسهولة Polar molecules (glucose and other sugars) do not cross easily لا تعبر الجزيئات القطبية (الجلوكوز والسكاكر الاخرى) بسهولة Membrane proteins called transport proteins play a “gatekeeper” role in selective permeability. Teaching Tips 1. You might wish to share a very simple analogy that seems to work well for some students. A cell membrane is a little like a peanut butter and jelly sandwich with jellybeans poked into it. The bread represents the hydrophilic portions of the bilayer (and bread does indeed quickly absorb water). The peanut butter and jelly represent the hydrophobic regions (and peanut butter, containing plenty of oil, is generally hydrophobic). The jellybeans stuck into the sandwich represent proteins variously embedded partially into or completely through the membrane. Transport proteins would be like the jellybeans that poke completely through the sandwich. Analogies are rarely perfect. Challenge your students to critique this analogy by finding exceptions. (For example, this analogy does not include a model of the carbohydrates on the cell surface.) Animation: Signal Transduction Pathways Animation: Overview of Cell Signaling Copyright © 2009 Pearson Education, Inc.

جزيئ مُنَشَّط جزيئ مرسال مستقبل Enzymesإنزيمان Activated Molecule
Messenger molecule جزيئ مرسال Enzymesإنزيمان Enzyme activity النشاط الإنزيمي Receptor مستقبل Activated Molecule جزيئ مُنَشَّط Figure 5.1B Enzyme activity. Signal transduction النقل الإشاري

Concentration gradient Transport النقل
High Concentration تركيز عالى Waterماء Actice transport النقل النشط from a region of higher to lower concentration Waterماء Figure 5.1D Transport. Diagram of a section of a membrane sac شكل يوضح قطاع في كيس غشائي Low Concentration تركيز منخفض Transport النقل

الانتشار هو عملية شيوع الجزيئات بالتساوي في فراغ متاح
5.3 Passive transport is diffusion across a membrane with no energy investment النقل السلبي هو الانتشار عبر غشاء دون استغلال طاقة Diffusion is a process in which particles spread out evenly in an available space الانتشار هو عملية شيوع الجزيئات بالتساوي في فراغ متاح Particles move from an area of more concentrated particles to an area where they are less concentrated تتحرك الجزيئات من منطقة ذات جزيئات أكثر تركيزاً لمنطقة يكون التركيز أقل بها This means that particles diffuse down their concentration gradient يعني هذا ان الجزيئات تنتشر أسفل مدرج التركيز (من مناطق التركيز العالي إلى مناطق التركيز المنخفض) Eventually, the particles reach equilibrium where the concentration of particles is the same throughout وأخيراً تبلغ الجزيئات حد الاتزان حيث يتساوى تركيز الجزيئات في كل مكان Much of the traffic across a membrane occurs by diffusion down its concentration gradient. This is exemplified by the diffusion of oxygen across the plasma membrane of a cell actively utilizing oxygen. As long as the cell is using the oxygen, the concentration from outside to inside will be maintained. For the BLAST Animation Diffusion, go to Animation and Video Files. Student Misconceptions and Concerns 1. For students with limited science backgrounds, concepts such as diffusion and osmosis can take considerable time to fully understand and apply. Instructors often struggle to remember a time in their lives when they did not know about such fundamental scientific principles. Consider spending extra time to illustrate and demonstrate these key processes to the class. Consider short interactive class exercises in which students create analogies or think of examples of these principles in their lives. Teaching Tips 1. Students often benefit from reminders of diffusion in their lives. Smells can usually be traced back to their sources—the smell of dinner on the stove, the scent of perfume or cologne from a bottle, the smoke drifting away from a campfire. These scents are strongest nearest the source and weaker as we move away. 2. Consider demonstrating simple diffusion. A large jar of water and a few drops of ark-colored dye work well over the course of a lecture period. Alternatively, release a strong scent of cologne or peppermint or peel part of an orange in the classroom and have students raise their hands as they first detect the smell. Students nearest the source will raise their hands before students farther away. The fan from an active overhead projector or overhead vent may bias the experiment a bit, so be aware of any directed movements of air in your classroom that might disrupt this demonstration. Copyright © 2009 Pearson Education, Inc.

Animation: Membrane Selectivity
5.3 Passive transport is diffusion across a membrane with no energy investment النقل السلبي هو الانتشار عبر غشاء دون استغلال طاقة Diffusion across a cell membrane does not require energy, so it is called passive transport لا يتطلب الانتشار خلال غشاء الخلية طاقة ، لذا يسمى بالنقل السلبي The concentration gradient itself represents potential energy for diffusion يمثل نفس مدرج التركيز طاقة كامنة للانتشار Because membranes are selectively permeable, they have different effects on the rates of diffusion of various molecules. For the BLAST Animation Passive Diffusion Across a Membrane, go to Animation and Video Files. Student Misconceptions and Concerns 1. For students with limited science backgrounds, concepts such as diffusion and osmosis can take considerable time to fully understand and apply. Instructors often struggle to remember a time in their lives when they did not know about such fundamental scientific principles. Consider spending extra time to illustrate and demonstrate these key processes to the class. Consider short interactive class exercises in which students create analogies or think of examples of these principles in their lives. Teaching Tips 1. Students often benefit from reminders of diffusion in their lives. Smells can usually be traced back to their sources—the smell of dinner on the stove, the scent of perfume or cologne from a bottle, the smoke drifting away from a campfire. These scents are strongest nearest the source and weaker as we move away. 2. Consider demonstrating simple diffusion. A large jar of water and a few drops of dark-colored dye work well over the course of a lecture period. Alternatively, release a strong scent of cologne or peppermint or peel part of an orange in the classroom and have students raise their hands as they first detect the smell. Students nearest the source will raise their hands before students farther away. The fan from an active overhead projector or overhead vent may bias the experiment a bit, so be aware of any directed movements of air in your classroom that might disrupt this demonstration. Animation: Diffusion Animation: Membrane Selectivity Copyright © 2009 Pearson Education, Inc.

Passive transport of one type of molecule
Molecules of dye جزيئات الصبغة Membraneغشاء Equilibriumإتزان Figure 5.3A Passive transport of one type of molecule. منطقة تركيز عالي منطقة تركيز منخفض مدرج تركيز Passive transport of one type of molecule النقل السلبي لنوع واحد من الجزيئات

Passive transport of two types of molecules
Two different Substances نوعين من الجزيئات Membraneغشاء Equilibriumالإتزان Figure 5.3B Passive transport of two types of molecules. Passive transport of two types of molecules النقل السلبي لنوعين من الجزيئات

It is crucial for cells that water moves across their membrane
5.4 Osmosis is the diffusion of water across a membrane الإسموزية هي انتشار الماء عبر غشاء (دون استغلال طاقة) It is crucial for cells that water moves across their membrane من الضروري للخلايا أن يتحرك الماء عبر غشائها Water moves across membranes in response to solute concentration inside and outside of the cell by a process called osmosis يتحرك الماء عبر الأغشية استجابة لتركيز المذاب داخل وخارج الخلية بعملية تسمى بالأسموزية Osmosis will move water across a membrane down its concentration gradient until the concentration of solute is equal on both sides of the membrane تحرك الأسموزية الماء عبر الغشاء تجاه أسفل مدرج التركيز إلى أن تتساوى درجة تركيز المذاب على كلا جانبي الغشاء Student Misconceptions and Concerns 1. For students with limited science backgrounds, concepts such as diffusion and osmosis can take considerable time to fully understand and apply. Instructors often struggle to remember a time in their lives when they did not know about such fundamental scientific principles. Consider spending extra time to illustrate and demonstrate these key processes to the class. Consider short interactive class exercises in which students create analogies or think of examples of these principles in their lives. Teaching Tips 1. Your students may have noticed that the skin of their fingers wrinkles after taking a long shower or bath, or after washing dishes. The skin wrinkles because it is swollen with water but still tacked down at some points. Through osmosis, water moves into the epidermal skin cells. Our skin is hypertonic to these solutions, producing the swelling that appears as large wrinkles. Oils inhibit the movement of water into our skin. Thus, soapy water results in wrinkling faster than plain water because the soap removes the natural layer of oil from our skin. Animation: Osmosis Copyright © 2009 Pearson Education, Inc.

Net flow of waterإتجاه تيار الماء
Osmosis, the diffusion of water across a membrane الاسموزية : انتشار الماء عبر غشاء Lower concentration of solute تركيز منخفض من المذاب Higher concentration of solute تركيز عالي من المذاب Equal concentration of solute تركيز متساوي من المذاب H2O Solute molecule جزيئات المذاب Selectively permeable membrane غشاء ذو نفاذية تفاضلية Water Molecule جزيئات ماء Figure 5.4 Osmosis, the diffusion of water across a membrane. Note that osmosis is a force that is actually able to cause a differential in water levels in the two arms of the U-tube shown in Figure 5.4. Solute molecule with cluster of water molecules جزيئات المذاب مع تجمعات من جزيئات الماء Net flow of waterإتجاه تيار الماء

التوتر مصطلح يصف مقدرة المحلول على إكساب أو فقد الخلية للماء
5.5 Water balance between cells and their surroundings is crucial to organisms اتزان الماء بين الخلايا ومحيطها ضرورة حتمية للكائنات الحية Tonicity is a term that describes the ability of a solution to cause a cell to gain or lose water التوتر مصطلح يصف مقدرة المحلول على إكساب أو فقد الخلية للماء Tonicity is dependent on the concentration of a nonpenetrating solute on both sides of the membrane يعتمد التوتر على تركيز مذاب غير نافذ على جانبي الغشاء Isotonic indicates that the concentration of a solute is the same on both sides يدل التوتر المتعادل على تركيز متساوي للمذاب على كلا جانبي الغشاء Hypertonic indicates that the concentration of solute is higher outside the cell يدل التوتر العالي على التركيز الأعلى للمذاب خارج الخلية Hypotonic indicates a higher concentration of solute inside the cell يدل التوتر المنخفض على التركيز الأعلى للمذاب داخل الخلية Seawater is isotonic to many marine invertebrates. The cells of most terrestrial animals are bathed in an extracellular fluid that is isotonic to their cells. If cells are put into a hypotonic or hypertonic solution, the results can be dangerous for the cell. Your students may have noticed that the skin of their fingers wrinkles after taking a long shower or bath or washing dishes. The skin wrinkles because it is swollen with water but still tacked down at some points. By osmosis, water moves into the epidermal skin cells. Our skin is hypertonic to these solutions, producing the swelling that appears as large wrinkles. Student Misconceptions and Concerns 1. Students easily confuse the term hypertonic and hypotonic. One challenge is to get them to understand that these are relative terms, like heavier, darker, or fewer. No single object is heavier, no single cup of coffee is darker, and no single bag of M & M’s has fewer candies. Such terms only apply when comparing two or more items. A solution with a higher concentration than another solution is hypertonic to that solution. However, the same solution might also be hypotonic to a third solution. Teaching Tips 1. The word root hypo- means “below.” Thus, a hypodermic needle injects substances below the dermis. Students might best remember that hypotonic solutions have concentrations of solutes below that of the other solution(s). 2. After introducing the idea of hypertonic and hypotonic solutions, you may wish to challenge your students with the following: A marine salmon moves from the ocean up a freshwater stream to reproduce. The salmon is moving from a _____ environment to a _____ environment. (Answers: hypertonic, hypotonic) 3. The effects of hypertonic and hypotonic solutions can be demonstrated if students soak carrot sticks, long slices of potato, or celery in hypertonic and hypotonic solutions. These also make nice class demonstrations. Copyright © 2009 Pearson Education, Inc.

Video: Paramecium Vacuole
5.5 Water balance between cells and their surroundings is crucial to organisms إتزان الماء بين الخلايا ومحيطها ضرورة حتمية حيوي للكائنات الحية Many organisms are able to maintain water balance within their cells by a process called osmoregulation تستطيع كثير من الكائنات الحفاظ على إتزانها المائي داخل خلاياها بواسطة عملية التنظيم الأسموزي This process prevents excessive uptake or excessive loss of water تمنع هذه العملية الكسب أو الفقد المفرطين للماء Plant, prokaryotic, and fungal cells have different issues with osmoregulation because of their cell walls يتعامل كل من النبات وأوليات النواة والفطريات بطرق مختلفة مع التنظيم الأسموزي بسبب جدر خلاياها Organisms with cell walls are protected from lysis when exposed to a hypotonic environment. Student Misconceptions and Concerns 1. Students easily confuse the term hypertonic and hypotonic. One challenge is to get them to understand that these are relative terms, like heavier, darker, or fewer. No single object is heavier, no single cup of coffee is darker, and no single bag of M & M’s has fewer candies. Such terms only apply when comparing two or more items. A solution with a higher concentration than another solution is hypertonic to that solution. However, the same solution might also be hypotonic to a third solution. Teaching Tips 1. The word root hypo- means “below.” Thus, a hypodermic needle injects substances below the dermis. Students might best remember that hypotonic solutions have concentrations of solutes below that of the other solution(s). 2. After introducing the idea of hypertonic and hypotonic solutions, you may wish to challenge your students with the following: A marine salmon moves from the ocean up a freshwater stream to reproduce. The salmon is moving from a _____ environment to a _____ environment. (Answers: hypertonic, hypotonic) 3. The effects of hypertonic and hypotonic solutions can be demonstrated if students soak carrot sticks, long slices of potato, or celery in hypertonic and hypotonic solutions. These also make nice class demonstrations. Video: Chlamydomonas Video: Plasmolysis Video: Paramecium Vacuole Video: Turgid Elodea Copyright © 2009 Pearson Education, Inc.

How animal and plant cells behave in different solutions
Isotonic solution محلول متعادل التوتر Hypotonic solution محلول منخفض التوتر Hypertonic solution محلول عالي التوتر Animal cell خلية جيوانية (A) Normalطبيعي (B) Lysedتحللت (C) Shriveledذبلت Plasma Membrane غشاء بلازمي Plant cell خلية نباتية Figure 5.5 How animal and plant cells behave in different solutions. (F) Shriveledذبلت (D) Flaccidترهلت (E) Turgidإنتفخت (plasmolyzedمبلزمة ) How animal and plant cells behave in different solutions كيف تتصرف كل من الخلايا الحيوانية والنباتية في المحاليل المختلفة

لا تنتشر كثير من المواد اللازمة لحيوية للخلية بحُرية خلال الغشاء
5.6 Transport proteins may facilitate diffusion across membranes قد تدعم بروتينات النقل الانتشار عبر الأغشية Many substances that are necessary for viability of the cell do not freely diffuse across the membrane لا تنتشر كثير من المواد اللازمة لحيوية للخلية بحُرية خلال الغشاء They require the help of specific transport proteins called aquaporins تحتاج هذه المواد لمساعدة بروتينات نقل معينة تعرف الأكوابورينات ”المثقبات المائية“ These proteins assist in facilitated diffusion, a type of passive transport that does not require energy تساعد هذه البروتينات في الانتشار المُدَعم ، نوع من النقل السلبي الذي لا يحتاج طاقة Polar molecules and ions that are impeded by the lipid bilayer diffuse with the help of transport proteins. Teaching Tips 1. The text notes that “the greater the number of transport proteins for a particular solute present in a membrane, the faster the solute’s rate of diffusion across the membrane.” This is similar to a situation that might be more familiar to your students. The more ticket-takers present at the entrance to a stadium, the faster the rate of movement of people into the stadium. Copyright © 2009 Pearson Education, Inc. 16

Some proteins function by becoming a hydrophilic tunnel for passage
5.6 Transport proteins may facilitate diffusion across membranes قد تدعم بروتينات النقل الانتشار عبر الأغشية Some proteins function by becoming a hydrophilic tunnel for passage تعمل بعض البروتينات بالتحول إلى قنوات محبة للماء لتسهل عمليات النفاذ Other proteins bind their passenger, change shape, and release their passenger on the other side بعض البروتينات ترتبط بالمادة المنقولة وتغير شكلها ومن ثم تطلقها في الناحية الأخرى In both of these situations, the protein is specific for the substrate, which can be sugars, amino acids, ions, and even water وفي كلتا الحالتين, يكون البروتين متخصص في المادة التي ينقلها ”معامل البروتين“, والتي قد تكون سكراً أو حمضاً امينياً أو ايونات أو حتى ماء Aquaporins, the water-channel proteins, facilitate the massive amount of diffusion that occurs in plant cells and red blood cells. Teaching Tips 1. The text notes that “the greater the number of transport proteins for a particular solute present in a membrane, the faster the solute’s rate of diffusion across the membrane.” This is similar to a situation that might be more familiar to your students. The more ticket-takers present at the entrance to a stadium, the faster the rate of movement of people into the stadium. Copyright © 2009 Pearson Education, Inc. 17

Solute molecule جزيء مُذاب Transport protein بروتين النقل
Figure 5.6 Transport protein providing a channel for the diffusion of a specific solute across a membrane. Transport protein بروتين النقل Transport protein providing a channel for the diffusion of a specific solute across a membrane يوفر بروتين النقل قناة انتشار لمُذاب معين عبر الغشاء 18

Animation: Active Transport
5.8 Cells expend energy in the active transport of a solute against its concentration gradient تبذل الخلايا طاقة أثناء عملية النقل النشط للمذاب عكس اتجاه مُدرج التركيز Cells have a mechanism for moving a solute against its concentration gradient تملك الخلايا آلية لتحريك المذاب عكس اتجاه مدرج التركيز It requires the expenditure of energy in the form of ATP يحتاج ذلك لبذل الطاقة على هيئة الـ ATP The mechanism alters the shape of the membrane protein through phosphorylation using ATP تغير الآلية شكل بروتينات الغشاء من خلال عملية الفسفره باستخدام الـ ATP The importance of these transport proteins is their ability to move solutes from a low concentration to a high concentration. ATP energy is required. The sodium-potassium pump that helps maintain gradients shuttles sodium and potassium across the membrane against their concentration gradients. The generation of nerve signals also depends on concentration differences. For the BLAST Animation Active Transport, go to Animation and Video Files. Teaching Tips 1. Active transport uses energy to move a solute against its concentration gradient. Challenge your students to think of the many possible analogies to this situation, for example, bailing out a leaky boat by moving water back to a place (outside the boat) where water is more concentrated. An alternative analogy might be the herding of animals, which requires work to keep the organisms concentrated and counteract their natural tendency to spread out. 2. Students familiar with city subway toll stations might think of some gate mechanisms that work similarly to the proteins regulating active transport. A person steps up to a barrier and inserts payment (analogous to ATP input), and the gate changes shape, permitting passage to the other side. Even a simple turnstile system that requires payment is generally similar. Animation: Active Transport Copyright © 2009 Pearson Education, Inc.

Active transport of a solute across a membrane
Protein بروتين نقل Transport النقل 3 Protein changes shape يغير البروتين شكله Protein reversion رجوع البروتين 4 Phosphate Detaches انفصال الفوسفات Solute مذاب Figure 5.8 Active transport of a solute across a membrane. Solute binding ارتباط المذاب Phosphorylation الفسفرة 1 2 Active transport of a solute across a membrane عملية النقل النشط للمذاب عبر غشاء

5.9 Exocytosis and endocytosis transport large molecules across membranes الطرد الخلوي والابتلاع الخلوي يقوما بنقل الجزيئات الكبيرة عبر الأغشية A cell uses two mechanisms for moving large molecules across membranes تستخدم الخلية آليتين لنقل الجزيئات الكبيرة عبر الأغشية Exocytosis is used to export bulky molecules, such as proteins or polysaccharides تُستخدم آلية الطرد الخلوي لتصدير الجزيئات الضخمة كالبروتينات أو متعدد السكريات إلى خارج الخلية Endocytosis is used to import substances useful to the livelihood of the cell تُستخدم آلية الابتلاع الخلوي لتوريد مواد نافعة لمعيشة الخلية إلى داخل الخلية In both cases, material to be transported is packaged within a vesicle that fuses with the membrane في كلتا الحالتين يتم تعبئة المواد المراد نقلها في حويصلات لتندمج بالغشاء البلازمي When the vesicles fuse with the cell membrane, the vesicle becomes part of the membrane. An example of exocytosis is the excretion of insulin by cells within the pancreas. Teaching Tips 1. Students carefully considering exocytosis might notice that membrane from secretory vesicles is added to the plasma membrane. Consider challenging your students to identify mechanisms that balance out this enlargement of the cell surface. (Endocytosis “subtracts” area from the cell surface. It is a major factor balancing out the additional membrane supplied by exocytosis.) Copyright © 2009 Pearson Education, Inc.

There are three kinds of endocytosis هناك ثلاثة أنواع من الطرد الخلوي
5.9 Exocytosis and endocytosis transport large molecules across membranes الطرد الخلوي والابتلاع الخلوي يقوما بنقل الجزيئات الكبيرة عبر الأغشية There are three kinds of endocytosis هناك ثلاثة أنواع من الطرد الخلوي Phagocytosis is engulfment of a particle by wrapping cell membrane around it, forming a vacuole البلعمة أو الإلتهام الخلوي هو ابتلاع الجزيئات بتغليفها بغشاء الخلية مكونة فجوة Pinocytosis is the same thing except that fluids are taken into small vesicles الشرب الخلوي عبارة عن نفس الشيء إلا أن السوائل هي التي تؤخذ في حويصلات صغيرة Receptor-mediated endocytosis is where receptors in a receptor-coated pit interact with a specific protein, initiating formation of a vesicle الابتلاع الخلوي بوساطة مستقبل حيث تتفاعل المستقبلات (في النقر المغلفة بالمستقبلات) مع بروتين معين لبدء تكوين حويصلة These mechanisms occur continually in most eukaryotic cells with the amount of plasma membrane remaining constant in a nongrowing cell. Apparently, the addition of membrane by one process offsets the loss of membrane by the other. For the BLAST Animation Endocytosis and Exocytosis, go to Animation and Video Files. Teaching Tips Students carefully considering exocytosis might notice that membrane from secretory vesicles is added to the plasma membrane. Consider challenging your students to identify mechanisms that balance out this enlargement of the cell surface. (Endocytosis “subtracts” area from the cell surface. It is a major factor balancing out the additional membrane supplied by exocytosis.) Animation: Exocytosis Animation: Pinocytosis Animation: Phagocytosis Animation: Receptor-Mediated Endocytosis Animation: Exocytosis and Endocytosis Introduction Copyright © 2009 Pearson Education, Inc.

Three kinds of endocytosis ثلاثة انواع من الابتلاع الخلوي
Food being ingested طعام يتم هضمه CYTOPLASMالسيتوبلازم EXTRACELLULAR FLUID السائل خارج خلوي Pseudopodium قدم كاذبة Phagocytosis الالتهام الخلوي “Food” or other particle قطعة غذاء او جسيم أخر Food vacuole فجوة غذائية Plasma membrane الغشاء البلازمي Three kinds of endocytosis ثلاثة انواع من الابتلاع الخلوي Pinocytosis الشرب الخلوي Vesicleفجوة Figure 5.9 Three kinds of endocytosis. Plasma membraneغشاء بلازمي Coat protein بروتين الغلاف Coated Vesicle حويصلة مغلفة Receptor مستقبل Receptor-mediated endocytosis الإدخال الخلوي بوساطة المستقبل Coated pit نقرة مغلفة Coated pit نقرة مغلفة Specific molecule جزيء محدد Material bound to receptor proteins مادة مرتبطة ببروتينات المستقبل

الطاقة والخلية ENERGY AND THE CELL
Copyright © 2009 Pearson Education, Inc.

5.10 Cells transform energy as they perform work تقوم الخلايا بتحويل الطاقة عند القيام بمهماتها
Cells are small units, a chemical factory, housing thousands of chemical reactions الخلايا وحدات صغيرة هي بمثابة مصانع كيميائية تحتضن آلاف التفاعلات الكيميائية The result of reactions is maintenance of the cell, manufacture of cellular parts, and replication ونتيجة هذه التفاعلات هي الحفاظ على الخلية وتصنيع أجزائها والتكاثر Student Misconceptions and Concerns 1. Students with limited exposure to physics may have never understood the concepts of energy and the conservation of energy or distinguished between potential and kinetic energy. Understanding such broad and new abstract concepts requires time and concrete examples. Teaching Tips 1. In our daily lives, we rely upon many energy transformations. On our classroom walls, a clock converts electrical energy to mechanical energy to sweep the hands around the clock’s face. Our physical (mechanical) activities walking to and from the classroom rely upon the chemical energy from our diet. This chemical energy in our diet also helps us maintain a steady body temperature (heat). Consider challenging your students to come up with additional examples of such common energy conversions. Copyright © 2009 Pearson Education, Inc.

5.10 Cells transform energy as they perform work تقوم الخلايا بتحويل الطاقة عند القيام بمهماتها
Energy is the capacity to do work and cause change الطاقة هي القدرة على عمل شغل لإحداث تغيير Work is accomplished when an object is moved against an opposing force, such as friction يُنجز الشغل حينما يُحرك شيء ضد قوة معاكسة مثل الاحتكاك There are two kinds of energy هناك نوعان من الطاقة Kinetic energy is the energy of motion الطاقة الحركية وهي طاقة الحركة Potential energy is energy that an object possesses as a result of its location الطاقة الكامنة وهي طاقة يمتلكها الشيء نتيجة لموقعه Energy is fundamental to all metabolic processes. Bioenergetics is the study of how energy flows through living organisms. Student Misconceptions and Concerns 1. Students with limited exposure to physics may have never understood the concepts of energy and the conservation of energy or distinguished between potential and kinetic energy. Understanding such broad and new abstract concepts requires time and concrete examples. Teaching Tips 1. In our daily lives, we rely upon many energy transformations. On our classroom walls, a clock converts electrical energy to mechanical energy to sweep the hands around the clock’s face. Our physical (mechanical) activities walking to and from the classroom rely upon the chemical energy from our diet. This chemical energy in our diet also helps us maintain a steady body temperature (heat). Consider challenging your students to come up with additional examples of such common energy conversions. Copyright © 2009 Pearson Education, Inc.

Potential energy being converted to kinetic energy
Figure 5.10A Kinetic energy, the energy of motion. Potential energy, stored energy as a result of location or structure الطاقة الكامنة: طاقة مختزنة نتيجة للموقع أو التركيب Potential energy being converted to kinetic energy الطاقة الكامنة عند تحولها إلى طاقة حركية Kinetic energy, the energy of motion الطاقة الحركية : هي طاقة الحركة

5.11 Two laws govern energy transformations قانونان يحكمان تحولات الطاقة
Energy transformations within matter are studied by individuals in the field of thermodynamics تحولات الطاقة في المادة يقوم بدراستها أشخاص متخصصون في مجال الديناميكا الحرارية Biologists study thermodynamics because an organism exchanges both energy and matter with its surroundings يدرس علماء الحياة الديناميكا الحرارية لأن الكائن الحي يتبادل الطاقة والمادة مع البيئة المحيطة به Some scientists study matter within a particular system. Some systems are isolated systems because they are unable to exchange energy or matter with their surroundings. An open system allows energy and matter to be transferred between the system and the surroundings. Organisms are open systems. Student Misconceptions and Concerns 1. Students with limited exposure to physics may have never understood the concepts of energy and the conservation of energy or distinguished between potential and kinetic energy. Understanding such broad and new abstract concepts requires time and concrete examples. 2. All too often we hear or read that some thing or reaction creates energy. We might hear or read that a power plant “produces” energy or that mitochondria “make” energy. Even in our classroom conversations, we may occasionally slip into this error. When discussing the first law of thermodynamics, consider emphasizing the inaccuracy of such statements. 3. Although typically familiar with the concept of dietary calories, students often struggle to think of calories as a source of potential energy. For many students, it is not clear that potential energy is stored in food as calories. Teaching Tips 1. Some students can relate well to the concept of entropy as applied to the room where they live. Despite cleaning up and organizing the room on a regular (or irregular) basis, the room becomes increasingly disorganized, a victim of entropy, until another energy input (or effort) is exerted to make the room more orderly again. Students might even get to know entropy as the “dorm room effect.” 2. The heat produced by the engine of a car is typically used to heat the car during cold weather. However, is this same heat available in warmer weather? Students are often unaware that their car “heater” works very well in the summer too. Just as exercise can warm us when it is cold, the same extra heat is released when we exercise in warm conditions. A car engine in the summer struggles to dissipate heat in the same way that a human struggles to cool off after exercising when weather is warm. 3. Here is a question that might make cellular respiration a little more meaningful to your students. Ask your students why they feel warm when it is 30°C (86°F) outside if their core body temperature is 37°C (98.6°F). Shouldn’t they feel cold? The answer is, our bodies are always producing heat. At these higher temperatures, we are producing more heat than we need, to maintain a core body temperature around 37°C. Thus, we sweat and behave in ways that help release our extra heat generated in cellular respiration. Copyright © 2009 Pearson Education, Inc.

تحولات الطاقة (مع زيادة الانتروبي) في سيارة وخلية
Waste products الفضلات الناتجة Fuelالوقود Energy conversionتحول الطاقة Heat energy طاقة حرارية Carbon dioxide ثاني أكسيد الكربون Gasolineجازولين Combustionاحتراق Kinetic energy of movement الطاقة الحركية اللازمة للحركة Oxygenأوكسجين Waterماء Energy conversion in a carتحول الطاقة في السيارة Energy transformations (with an increase in entropy) in a car and a cell. تحولات الطاقة (مع زيادة الانتروبي) في سيارة وخلية Heatحرارة Figure 5.11 Energy transformations (with an increase in entropy) in a car and a cell. Cellular respirationالتنفس الخلوي Glucoseجلوكوز Carbon dioxide ثاني أكسيد الكربون Oxygenأكسجين Waterماء Energy for cellular workطاقة الشغل الخلوي Energy conversion in a cellتحول الطاقة في الخلية

5.12 Chemical reactions either release or store energy التفاعلات الكيميائية إما أن تحرر أو تختزن الطاقة A living organism produces thousands of endergonic and exergonic chemical reactions يقوم الكائن الحي بالآلاف من التفاعلات الكيميائية المُحَرِرة والمستقبلة للطاقة All of these combined is called metabolism كل تلك التفاعلات مجتمعة تسمي بالأيض A metabolic pathway is a series of chemical reactions that either break down a complex molecule or build up a complex molecule المسار الأيضي عبارة عن سلسلة من التفاعلات الكيميائية والتي إما تهدم أو تبني جزيء معقد Metabolism requires energy, which is taken from sugar or other molecules containing energy. Student Misconceptions and Concerns 1. Students with limited exposure to physics may have never understood the concepts of energy and the conservation of energy or distinguished between potential and kinetic energy. Understanding such broad and new abstract concepts requires time and concrete examples. 2. Energy coupling at the cellular level may be new to many students, but it is a familiar concept when related to the use of money in our society. Students might be discouraged if the only benefit of work was the ability to make purchases from the employer. (We all might soon tire of a fast-food job that only paid its employees in food!) Money permits the coupling of a generation of value (a paycheck, analogous to an energy-releasing reaction) to an energy-consuming reaction (money, which allows us to make purchases in distant locations). This idea of earning and spending is a common concept we all know well. Teaching Tips 1. The same mass of fat stores nearly twice as many calories (about 9 kcal per gram) as an equivalent mass of protein or carbohydrates (about 4.5–5 kcal per gram). Thus, when comparing equal masses of fat, protein, and lipid, the fat has nearly twice the potential energy. Fat is therefore an efficient way to store energy in animals and many plants. To store an equivalent amount of energy in the form of carbohydrates or proteins would require about twice the mass, adding a significant burden to the organism’s structure. (For example, if you were 20 lbs overweight, you would be nearly 40 lbs overweight if the same energy were stored as carbohydrates or proteins instead of fat). 2. The amount of energy each adult human needs to generate the ATP required in a day is tremendous. Here is a calculation that has impressed many students. Depending upon the size and activity of a person, a human might burn 2,000 dietary calories (kilocalories) a day. This is enough energy to raise the temperature of 20 liters of liquid water from 0° to 100°C. This is something to think about the next time you heat water on the stove! If you can bring in ten 2-liter bottles, you can help students visualize how much liquid water can be raised from 0° to 100°C. (Note: 100 calories raises about 1 liter of water 100°C, but it takes much more energy to melt ice or to convert boiling water into steam.) Copyright © 2009 Pearson Education, Inc.

5.12 Chemical reactions either release or store energy التفاعلات الكيميائية إما أن تحرر أو تختزن الطاقة A cell does three main types of cellular work تقوم الخلية بعمل ثلاثة أنواع رئيسية من الشغل Chemical work—driving endergonic reactions شغل كيميائي – تحريك التفاعلات المستقبلة للطاقة Transport work—pumping substances across membranes شفل نقلي – ضخ المواد عبر الأغشية Mechanical work— beating of cilia شغل آلي – حركة الأهداب To accomplish work, a cell must manage its energy resources, and it does so by energy coupling—the use of exergonic processes to drive an endergonic one لابد أن تنظم الخلية مصادر الطاقة لتنجز شغلاً وتقوم بذلك بإقران الطاقة – استخدام التفاعلات المحررة للطاقة لإمداد التفاعلات المستقبله للطاقة بما تحتاجه من الطاقة ATP is responsible for mediating most energy coupling in cells. Student Misconceptions and Concerns 1. Students with limited exposure to physics may have never understood the concepts of energy and the conservation of energy or distinguished between potential and kinetic energy. Understanding such broad and new abstract concepts requires time and concrete examples. 2. Energy coupling at the cellular level may be new to many students, but it is a familiar concept when related to the use of money in our society. Students might be discouraged if the only benefit of work was the ability to make purchases from the employer. (We all might soon tire of a fast-food job that only paid its employees in food!) Money permits the coupling of a generation of value (a paycheck, analogous to an energy-releasing reaction) to an energy-consuming reaction (money, which allows us to make purchases in distant locations). This idea of earning and spending is a common concept we all know well. Teaching Tips 1. The same mass of fat stores nearly twice as many calories (about 9 kcal per gram) as an equivalent mass of protein or carbohydrates (about 4.5–5 kcal per gram). Thus, when comparing equal masses of fat, protein, and lipid, the fat has nearly twice the potential energy. Fat is therefore an efficient way to store energy in animals and many plants. To store an equivalent amount of energy in the form of carbohydrates or proteins would require about twice the mass, adding a significant burden to the organism’s structure. (For example, if you were 20 lbs overweight, you would be nearly 40 lbs overweight if the same energy were stored as carbohydrates or proteins instead of fat). 2. The amount of energy each adult human needs to generate the ATP required in a day is tremendous. Here is a calculation that has impressed many students. Depending upon the size and activity of a person, a human might burn 2,000 dietary calories (kilocalories) a day. This is enough energy to raise the temperature of 20 liters of liquid water from 0° to 100°C. This is something to think about the next time you heat water on the stove! If you can bring in ten 2-liter bottles, you can help students visualize how much liquid water can be raised from 0° to 100°C. (Note: 100 calories raises about 1 liter of water 100°C, but it takes much more energy to melt ice or to convert boiling water into steam.) Copyright © 2009 Pearson Education, Inc.

ATP, adenosine triphosphate, is the energy currency of cells.
5.13 ATP shuttles chemical energy and drives cellular work ينقل الـ ATPالطاقة الكيميائية اللازمة للخلية للقيام بمهماتها ATP, adenosine triphosphate, is the energy currency of cells. ثلاثي فوسفات الأدينوسين ((ATP هو ”عُملة“ الطاقة في الخلية ATP is the immediate source of energy that powers most forms of cellular work. ATP هو مصدر الطاقة الفوري الذي يزود معظم أشكال الشغل الخلوي بالطاقة It is composed of adenine (a nitrogenous base), ribose (a five-carbon sugar), and three phosphate groups. يتكون من أدينين (قاعدة نتروجينية) ، رايبوز (سكر خماسي الكربون) ، وثلاث مجاميع فوسفات The phosphate group serves as a functional group, and the hydrolysis of this group releases energy. ATP is also one of the nucleoside triphosphates used to make RNA. Student Misconceptions and Concerns 1. Students with limited exposure to physics may have never understood the concepts of energy and the conservation of energy or distinguished between potential and kinetic energy. Understanding such broad and new abstract concepts requires time and concrete examples. 2. Energy coupling at the cellular level may be new to many students, but it is a familiar concept when related to the use of money in our society. Students might be discouraged if the only benefit of work was the ability to make purchases from the employer. (We all might soon tire of a fast-food job that only paid its employees in food!) Money permits the coupling of a generation of value (a paycheck, analogous to an energy-releasing reaction) to an energy-consuming reaction (money, which allows us to make purchases in distant locations). This idea of earning and spending is a common concept we all know well. Teaching Tips 1. The amount of energy each adult human needs to generate the ATP required in a day is tremendous. Here is a calculation that has impressed many students. Depending upon the size and activity of a person, a human might burn 2,000 dietary calories (kilocalories) a day. This is enough energy to raise the temperature of 20 liters of liquid water from 0° to 100°C. This is something to think about the next time you heat water on the stove! If you can bring in ten 2-liter bottles, you can help students visualize how much liquid water can be raised from 0° to 100°C. (Note: 100 calories raises about 1 liter of water 100°C, but it takes much more energy to melt ice or to convert boiling water into steam.) 2. When introducing ATP and ADP, consider having them think of the terms as A-3-P and A-2-P, noting that the word roots tri- = 3 and di- = 2. It might help students to keep track of the number of phosphates more easily. 3. Recycling is essential in cell biology. Damaged organelles are broken down intracellularly and chemical components, the monomers of the cytoskeleton, and ADP are routinely recycled. There are several advantages common to human recycling of garbage and cellular recycling. Both save energy by avoiding the need to remanufacture the basic units, and both avoid an accumulation of waste products that could interfere with other “environmental” chemistry (the environment of the cell or the environment of the human population). Copyright © 2009 Pearson Education, Inc.

5.13 ATP shuttles chemical energy and drives cellular work ينقل الـ ATPالطاقة الكيميائية اللازمة للخلية للقيام بمهماتها Hydrolysis of ATP releases energy by transferring its third phosphate from ATP to some other molecule تؤدي حلمأة ”التحليل المائي“ الـ ATP إلى تحرر طاقة وذلك بنقل فوسفاته الثالث من الـ ATP لمركب آخر The transfer is called phosphorylation يسمى هذا النقل بالفسفرة In the process, ATP energizes molecules يمد ATP الجزيئات بالطاقة أثناء هذه العملية For the BLAST Animation ATP/ADP Cycle, go to Animation and Video Files. Student Misconceptions and Concerns 1. Students with limited exposure to physics may have never understood the concepts of energy and the conservation of energy or distinguished between potential and kinetic energy. Understanding such broad and new abstract concepts requires time and concrete examples. 2. Energy coupling at the cellular level may be new to many students, but it is a familiar concept when related to the use of money in our society. Students might be discouraged if the only benefit of work was the ability to make purchases from the employer. (We all might soon tire of a fast-food job that only paid its employees in food!) Money permits the coupling of a generation of value (a paycheck, analogous to an energy-releasing reaction) to an energy-consuming reaction (money, which allows us to make purchases in distant locations). This idea of earning and spending is a common concept we all know well. Teaching Tips 1. The amount of energy each adult human needs to generate the ATP required in a day is tremendous. Here is a calculation that has impressed many students. Depending upon the size and activity of a person, a human might burn 2,000 dietary calories (kilocalories) a day. This is enough energy to raise the temperature of 20 liters of liquid water from 0° to 100°C. This is something to think about the next time you heat water on the stove! If you can bring in ten 2-liter bottles, you can help students visualize how much liquid water can be raised from 0° to 100°C. (Note: 100 calories raises about 1 liter of water 100°C, but it takes much more energy to melt ice or to convert boiling water into steam.) 2. When introducing ATP and ADP, consider having them think of the terms as A-3-P and A-2-P, noting that the word roots tri- = 3 and di- = 2. It might help students to keep track of the number of phosphates more easily. 3. Recycling is essential in cell biology. Damaged organelles are broken down intracellularly and chemical components, the monomers of the cytoskeleton, and ADP are routinely recycled. There are several advantages common to human recycling of garbage and cellular recycling. Both save energy by avoiding the need to remanufacture the basic units, and both avoid an accumulation of waste products that could interfere with other “environmental” chemistry (the environment of the cell or the environment of the human population). Copyright © 2009 Pearson Education, Inc.

+ طاقة تركيب وحلمأة ”التحليل المائي“ ATP
Adenosine أدينوسين Triphosphate (ATP) ثلاثي الفوسفات (ATP) The structure and hydrolysis of ATP. The reaction of ATP and water yields ADP , a phosphate group, and energy تركيب وحلمأة ”التحليل المائي“ ATP يعطي تفاعل ATP مع الماء : ADP ومجموعة فوسفات وطاقة Phosphate group مجموعة فوسفات Adenineأدنين Riboseريبوز Hydrolysis حلمأة ”تحليل مائي“ Diphosphate (ADP) (ADP) ثنائي الفوسفات + Adenosine أدينوسين طاقة Figure 5.13A The structure and hydrolysis of ATP. The reaction of ATP and water yields ADP, a phosphate group, and energy.

طاقة من تفاعلات معطية للطاقة طاقة لتفاعلات مستقبلة للطاقة
Phosphorylation الحلمأة ”تحلل مائي” Hydrolysis فسفرة Energy from exergonic reactions طاقة من تفاعلات معطية للطاقة Energy for endergonic reactions طاقة لتفاعلات مستقبلة للطاقة Figure 5.13C The ATP cycle. The ATP cycle دورة الـ ATP

كيفية عمل الإنزيمات HOW ENZYMES FUNCTION

Animation: How Enzymes Work
5.14 Enzymes speed up the cell’s chemical reactions by lowering energy barriers تسرع الإنزيمات من تفاعلات الخلية الكيميائية بتقليل حواجز الطاقة The cell uses catalysis to drive (speed up) biological reactions تستخدم الخلية عملية الحفز لتسريع التفاعلات الحيوية Catalysis is accomplished by enzymes, which are proteins that function as biological catalysts يتم انجاز عملية الحفز بالإنزيمات وهي بروتينات تعمل كمحفزات حيوية Each enzyme has a particular target molecule called the substrate كل إنزيم له هدف محدد من الجزيئات يسمى بعامل الإنزيم Most enzymes are proteins, but RNA enzymes, also called ribozymes, also catalyze reactions. Student Misconceptions and Concerns 1. For students not previously familiar with activation energy, analogies can make all the difference. Activation energy can be thought of as a small input that is needed to trigger a large output. This is like (a) an irritated person who needs only a bit more frustration to explode in anger, (b) small waves that lift debris over a dam, or (c) lighting a match around lighter fluid. In each situation, the output is much greater than the input. Teaching Tips 1. The information in DNA is used to direct the production of RNA, which in turn directs the production of proteins. However, in Chapter 3, four different types of biological molecules were noted as significant components of life. Students who think this through might wonder, and you could point out that DNA does not directly control the production of carbohydrates and lipids. So how does DNA exert its influence over the synthesis of these two chemical groups? The answer is largely by way of enzymes, proteins with the ability to promote the production of carbohydrates and lipids. Animation: How Enzymes Work Copyright © 2009 Pearson Education, Inc.

Enzymes have unique three-dimensional shapes
5.15 A specific enzyme catalyzes each cellular reaction كل تفاعلاً خلوياً يحفز بواسطة إنزيماً معيناً Enzymes have unique three-dimensional shapes الإنزيمات لها شكل ثلاثي الأبعاد فريد من نوعه The shape is critical to their role as biological catalysts الشكل أساسي لدورها كعوامل تحفيز حيوية As a result of its shape, the enzyme has an active site where the enzyme interacts with the enzyme’s substrate ونتيجة لشكله, يمتلك الإنزيم منطقة نشطة حيث يتفاعل مع عامل الإنزيم الخاص به Consequently, the substrate’s chemistry is altered to form the product of the enzyme reaction وبالتالي, تتغير الطبيعة الكيميائية لعامل الإنزيم لتكوين الناتج من التفاعل الإنزيمي Student Misconceptions and Concerns 1. The specific interactions of enzymes and substrates can be illustrated with simple physical models. Many students new to these concepts will benefit from several forms of explanation, including diagrams such as those in the textbook, physical models, and the opportunity to manipulate or create their own examples. Just like pitching a tent, new concepts are best constructed with many lines of support. Teaching Tips 1. The information in DNA is used to direct the production of RNA, which in turn directs the production of proteins. However, in Chapter 3, four different types of biological molecules were noted as significant components of life. Students who think this through might wonder, and you could point out that DNA does not directly control the production of carbohydrates and lipids. So how does DNA exert its influence over the synthesis of these two chemical groups? The answer is largely by way of enzymes, proteins with the ability to promote the production of carbohydrates and lipids. 2. The text notes that the relationship between an enzyme and its substrate is like a handshake, with each hand generally conforming to the shape of the other. This induced fit is also like the change in shape of a glove when a hand is inserted. The glove’s general shape matches the hand, but the final “fit” requires some additional adjustments. Copyright © 2009 Pearson Education, Inc.

1 2 3 4 The catalytic cycle of an enzyme دورة الحفز للإنزيم
Enzyme available with empty active site إنزيم مُجهز بموضع نشط فارغ Active siteالموضع النشط 1 Enzyme (sucrase) إنزيم (السكاريز- مُحلل للسكر) Substrate binds to enzyme with induced fit يرتبط العامل بإنزيمه بعملية حث مناسبة 2 Substrate (sucrose) عامل إنزيمي (السكروز – سكر القصب) Products are released تحرر النواتج 4 Fructoseفروكتوز Glucoseجلوكوز The catalytic cycle of an enzyme دورة الحفز للإنزيم Substrate is converted to products يتحول العامل الانزيمي إلى نواتج 3 Figure 5.15 The catalytic cycle of an enzyme.

High temperature will denature human enzymes
5.15 A specific enzyme catalyzes each cellular reaction كل تفاعل خلوي يٌحَفز بواسطة إنزيم معين For optimum activity, enzymes require certain environmental conditions يحتاج الإنزيم لظروف بيئية معينة للقيام بنشاطه الأمثل Temperature is very important, and optimally, human enzymes function best at 37ºC, or body temperature درجة الحرارة هامة جداً ، حيث تعمل إنزيمات الإنسان بطريقة أفضل وأمثل عند درجة حرارة 37 درجة مئوية (أو درجة حرارة الجسم) High temperature will denature human enzymes درجة الحرارة العالية تؤدي إلى مسخ ”تغير طبيعة“ إنزيمات الإنسان Enzymes also require a pH around neutrality for best results تتطلب الإنزيمات أيضاًpH متعادل تقريباً من أجل نتائج أفضل Certain chemicals also alter enzyme function and have been used to kill bacteria. For the BLAST Animation Enzymes: Types and Specificity, go to Animation and Video Files. Student Misconceptions and Concerns 1. The specific interactions of enzymes and substrates can be illustrated with simple physical models. Many students new to these concepts will benefit from several forms of explanation, including diagrams such as those in the textbook, physical models, and the opportunity to manipulate or create their own examples. Just like pitching a tent, new concepts are best constructed with many lines of support. Teaching Tips 1. The information in DNA is used to direct the production of RNA, which in turn directs the production of proteins. However, in Chapter 3, four different types of biological molecules were noted as significant components of life. Students who think this through might wonder, and you could point out that DNA does not directly control the production of carbohydrates and lipids. So how does DNA exert its influence over the synthesis of these two chemical groups? The answer is largely by way of enzymes, proteins with the ability to promote the production of carbohydrates and lipids. 2. The text notes that the relationship between an enzyme and its substrate is like a handshake, with each hand generally conforming to the shape of the other. This induced fit is also like the change in shape of a glove when a hand is inserted. The glove’s general shape matches the hand, but the final “fit” requires some additional adjustments. Copyright © 2009 Pearson Education, Inc.

Some enzymes require nonprotein helpers
5.15 A specific enzyme catalyzes each cellular reaction كل تفاعل خلوي يحفز بواسطة إنزيم معين Some enzymes require nonprotein helpers تحتاج بعض الإنزيمات مساعدات غير بروتينية Cofactors are inorganic, such as zinc, iron, or copper العوامل المرافقة هي مواد غير عضوية مثل الزنك والحديد والنحاس Coenzymes are organic molecules and are often vitamins مرافقات الإنزيمات هي جزيئات عضوية وغالباً تكون فيتامينات We need vitamins in our food or as supplements because of their role in metabolism driven by enzymes. Student Misconceptions and Concerns 1. The specific interactions of enzymes and substrates can be illustrated with simple physical models. Many students new to these concepts will benefit from several forms of explanation, including diagrams such as those in the textbook, physical models, and the opportunity to manipulate or create their own examples. Just like pitching a tent, new concepts are best constructed with many lines of support. Teaching Tips 1. The information in DNA is used to direct the production of RNA, which in turn directs the production of proteins. However, in Chapter 3, four different types of biological molecules were noted as significant components of life. Students who think this through might wonder, and you could point out that DNA does not directly control the production of carbohydrates and lipids. So how does DNA exert its influence over the synthesis of these two chemical groups? The answer is largely by way of enzymes, proteins with the ability to promote the production of carbohydrates and lipids. 2. The text notes that the relationship between an enzyme and its substrate is like a handshake, with each hand generally conforming to the shape of the other. This induced fit is also like the change in shape of a glove when a hand is inserted. The glove’s general shape matches the hand, but the final “fit” requires some additional adjustments. Copyright © 2009 Pearson Education, Inc.

Inhibitors are chemicals that inhibit an enzyme’s activity
5.16 Enzyme inhibitors block enzyme action and can regulate enzyme activity in a cell مثبطات الإنزيم تمنع عمله كما وتنظم نشاطه في الخلية Inhibitors are chemicals that inhibit an enzyme’s activity المثبطات هي مواد كيميائية تثبط النشاط الإنزيمي One group inhibits because they compete for the enzyme’s active site and thus block substrates from entering the active site إحدى هذه المجاميع تقوم بالتثبيط لأنها تستبق نحو الموقع النشط في الإنزيم وبالتالي تحجب عامله من دخول ذلك الموقع These are called competitive inhibitors وتسمى هذه بالمثبطات التنافسية Penicillin, an antibiotic, is an example of a noncompetitive inhibitor because it blocks the active site of an enzyme that some bacteria use to make their cell wall. For the BLAST Animation Enzyme Regulation: Chemical Modification, go to Animation and Video Files. For the BLAST Animation Enzyme Regulation: Competitive Inhibition, go to Animation and Video Files. Student Misconceptions and Concerns 1. The specific interactions of enzymes and substrates can be illustrated with simple physical models. Many students new to these concepts will benefit from several forms of explanation, including diagrams such as those in the textbook, physical models, and the opportunity to manipulate or create their own examples. Just like pitching a tent, new concepts are best constructed with many lines of support. Teaching Tips 1. The information in DNA is used to direct the production of RNA, which in turn directs the production of proteins. However, in Chapter 3, four different types of biological molecules were noted as significant components of life. Students who think this through might wonder, and you could point out that DNA does not directly control the production of carbohydrates and lipids. So how does DNA exert its influence over the synthesis of these two chemical groups? The answer is largely by way of enzymes, proteins with the ability to promote the production of carbohydrates and lipids. 2. Enzyme inhibitors that block the active site are like (a) a person sitting in your assigned theater seat or (b) a car parked in your parking space. Analogies for inhibitors that change the shape of the active site are more difficult to imagine. Consider challenging your students to think of such analogies. (Perhaps someone adjusting the driver seat of the car differently from your preferences and then leaving it that way when you try to use the car.) 3. Feedback inhibition relies upon the negative feedback of the accumulation of a product. Ask students in class to suggest other products of reactions that inhibit the process that made them when the product reaches high enough levels. (Gas station pumps routinely shut off when a high level of gasoline is detected. Furnaces typically turn off when enough heat has been produced.) 4. Challenge your class to identify advantages of specific enzyme inhibitors for pest control. These advantages include (a) the ability to target chemical reactions of only certain types of pest organisms and (b) the ability to target chemical reactions that are found in insects but not in humans. Copyright © 2009 Pearson Education, Inc.

Normal binding of substrateارتباط طبيعي لعامل الإنزيم
Active site الموقع النشطة Enzyme إنزيم Normal binding of substrateارتباط طبيعي لعامل الإنزيم How inhibitors interfere with substrate bindingكيفية تداخل المثبطات مع ارتباط عوامل الإنزيم Competitive Inhibitor مثبط تنافسي Noncompetitive Inhibitor مثبط غير تنافسي Figure 5.16 How inhibitors interfere with substrate binding. Enzyme inhibitionالتثبيط الإنزيمي

Other inhibitors do not act directly with the active site
5.16 Enzyme inhibitors block enzyme action and can regulate enzyme activity in a cell مثبطات الإنزيم تمنع عمله كما وتنظم نشاطه في الخلية Other inhibitors do not act directly with the active site لا تتعامل المثبطات الأخرى مباشرة مع الموقع النشط These bind somewhere else and change the shape of the enzyme so that the substrate will no longer fit the active site ترتبط هذه المثبطات بمكان آخر من الانزيم مغيره شكله فلا يصبح الموقع النشط مناسباً لعامل الانزيم These are called noncompetitive inhibitors تسمى هذه المجموعة بالمثبطات غير التنافسية Student Misconceptions and Concerns 1. The specific interactions of enzymes and substrates can be illustrated with simple physical models. Many students new to these concepts will benefit from several forms of explanation, including diagrams such as those in the textbook, physical models, and the opportunity to manipulate or create their own examples. Just like pitching a tent, new concepts are best constructed with many lines of support. Teaching Tips 1. The information in DNA is used to direct the production of RNA, which in turn directs the production of proteins. However, in Chapter 3, four different types of biological molecules were noted as significant components of life. Students who think this through might wonder, and you could point out that DNA does not directly control the production of carbohydrates and lipids. So how does DNA exert its influence over the synthesis of these two chemical groups? The answer is largely by way of enzymes, proteins with the ability to promote the production of carbohydrates and lipids. 2. Enzyme inhibitors that block the active site are like (a) a person sitting in your assigned theater seat or (b) a car parked in your parking space. Analogies for inhibitors that change the shape of the active site are more difficult to imagine. Consider challenging your students to think of such analogies. (Perhaps someone adjusting the driver seat of the car differently from your preferences and then leaving it that way when you try to use the car.) 3. Feedback inhibition relies upon the negative feedback of the accumulation of a product. Ask students in class to suggest other products of reactions that inhibit the process that made them when the product reaches high enough levels. (Gas station pumps routinely shut off when a high level of gasoline is detected. Furnaces typically turn off when enough heat has been produced.) 4. Challenge your class to identify advantages of specific enzyme inhibitors for pest control. These advantages include (a) the ability to target chemical reactions of only certain types of pest organisms and (b) the ability to target chemical reactions that are found in insects but not in humans. Copyright © 2009 Pearson Education, Inc.

Enzyme inhibitors are important in regulating cell metabolism
5.16 Enzyme inhibitors block enzyme action and can regulate enzyme activity in a cell مثبطات الإنزيم تمنع عمله كما وتنظم نشاطه في الخلية Enzyme inhibitors are important in regulating cell metabolism المثبطات الإنزيمية هامة في تنظيم الأيض الخلوي Often the product of a metabolic pathway can serve as an inhibitor of one enzyme in the pathway, a mechanism called feedback inhibition غالباً ما يعمل أحد نواتج مسار آيضي كمثبط لأحد الإنزيمات في ذلك المسار ، وتسمى هذه الآلية بالتثبيط الرجعي The more product formed, the greater the inhibition, and in this way, regulation of the pathway is accomplished كلما ازداد تكوين المنتج, كلما ازداد التثبيط, وبهذه الطريقة يتم تنظيم المسار Student Misconceptions and Concerns 1. The specific interactions of enzymes and substrates can be illustrated with simple physical models. Many students new to these concepts will benefit from several forms of explanation, including diagrams such as those in the textbook, physical models, and the opportunity to manipulate or create their own examples. Just like pitching a tent, new concepts are best constructed with many lines of support. Teaching Tips 1. The information in DNA is used to direct the production of RNA, which in turn directs the production of proteins. However, in Chapter 3, four different types of biological molecules were noted as significant components of life. Students who think this through might wonder, and you could point out that DNA does not directly control the production of carbohydrates and lipids. So how does DNA exert its influence over the synthesis of these two chemical groups? The answer is largely by way of enzymes, proteins with the ability to promote the production of carbohydrates and lipids. 2. Enzyme inhibitors that block the active site are like (a) a person sitting in your assigned theater seat or (b) a car parked in your parking space. Analogies for inhibitors that change the shape of the active site are more difficult to imagine. Consider challenging your students to think of such analogies. (Perhaps someone adjusting the driver seat of the car differently from your preferences and then leaving it that way when you try to use the car.) 3. Feedback inhibition relies upon the negative feedback of the accumulation of a product. Ask students in class to suggest other products of reactions that inhibit the process that made them when the product reaches high enough levels. (Gas station pumps routinely shut off when a high level of gasoline is detected. Furnaces typically turn off when enough heat has been produced.) 4. Challenge your class to identify advantages of specific enzyme inhibitors for pest control. These advantages include (a) the ability to target chemical reactions of only certain types of pest organisms and (b) the ability to target chemical reactions that are found in insects but not in humans. Copyright © 2009 Pearson Education, Inc.

Requires no energy Requires energy Passive transport Active transport
Diffusion Facilitated diffusion Osmosis Higher solute concentration Higher water concentration Higher solute concentration Solute Water Lower solute concentration Lower water concentration Lower solute concentration

How Cells Harvest Chemical Energy كيف تحصد الخلايا الطاقة الكيميائية
Chapter 6 الباب السادس How Cells Harvest Chemical Energy كيف تحصد الخلايا الطاقة الكيميائية Lecture by Richard L. Myers

Introduction: How Is a Marathoner Different from a Sprinter
The percentage of slow and fast muscle fibers determines the difference between track athletes تحدد النسبة المئوية لألياف العضلات السريعة والبطيئة الفرق في سباق الرياضيين Those with a large percentage of slow fibers make the best long-distance runners يشكل ذوي النسب المئوية العالية من الألياف البطيئة أفضل عدائي المسافات الطويلة Those with more fast fibers are good sprinters في حين ان ذوي الالياف السريعة يجيدون العدو السريع لمسافات قصيرة All of our cells harvest chemical energy (ATP) from our food تحصد كل خلايانا الطاقة الكيميائية (ATP) من الغذاء Aerobic breakdown of food is called cellular respiration. Copyright © 2009 Pearson Education, Inc.

INTRODUCTION TO CELLULAR RESPIRATION
مقدمة في التنفس الخلوي Copyright © 2009 Pearson Education, Inc.

Energy is necessary for life processes
6.1 Photosynthesis and cellular respiration provide energy for life يعمل البناء الضوئي والتنفس الخلوي على تزويد الحياة بما تحتاجه من الطاقة Energy is necessary for life processes الطاقة ضرورية في العمليات الحيوية These include growth, transport, manufacture, movement, reproduction, and others تشمل هذه العلميات النمو والنقل والتصنيع والحركة والتكاثر وأشياء أخرى Energy that supports life on Earth is captured from sun rays reaching Earth through plant, algae, protist, and bacterial photosynthesis تؤخذ الطاقة التي تدعم الحياة على كوكب الأرض من أشعة الشمس التي تصل الارض عن طريق النباتات والطحالب والأوليات وبكتيريا البناء الضوئي During photosynthesis, light energy is converted to chemical energy. Student Misconceptions and Concerns 1. Students should be cautioned against the assumption that energy is created when it is converted from one form to another. This might be a good time to review the principle of conservation of energy (the first law of thermodynamics addressed in Module 5.11). Teaching Tips 1. You might wish to elaborate on the amount of solar energy striking Earth. Every day Earth is bombarded with solar radiation equal to the energy of 100 million atomic bombs. Of the tiny fraction of light that reaches photosynthetic organisms, only about 1% is converted to chemical energy by photosynthesis. 2. Energy coupling at the cellular level may be new to many students, but it is a familiar concept when related to the use of money in our society. Students might be discouraged if the only benefit of work was the ability to make purchases from the employer. (We all might soon tire of a fast-food job that only paid its employees in food!) Money permits the coupling of a generation of value (a paycheck, analogous to an energy-releasing reaction) to an energy-consuming reaction (money, which allows us to make purchases in distant locations). This idea of earning and spending is a common concept we all know well. Copyright © 2009 Pearson Education, Inc.

6.1 Photosynthesis and cellular respiration provide energy for life يعمل البناء الضوئي والتنفس الخلوي على تزويد الحياة بما تحتاجه من الطاقة Energy in sunlight is used in photosynthesis to make glucose from CO2 and H2O with release of O2 تستخدم طاقة ضوء الشمس في البناء الضوئي لصنع الجلوكوز من ثاني أكسيد كربون والماء مع تحرير الأوكسجين كما يحدث في النبات الاخضر Other organisms use the O2 and energy in sugar and release CO2 and H2O تستخدم كائنات أخرى (الحيوانات مثلا)الأوكسجين لتحرير الطاقة المختزنة في السكر وثاني أكسيد الكربون والماء Together, these two processes are responsible for the majority of life on Earth ان هاتان العمليتان معا هما المسئولتان عن غالبية الحياة على كوكب الارض One can, therefore, say that life on Earth is solar powered. For the Discovery Video Space Plants, go to the Animation and Video Files. Student Misconceptions and Concerns 1. Students should be cautioned against the assumption that energy is created when it is converted from one form to another. This might be a good time to review the principle of conservation of energy (the first law of thermodynamics addressed in Module 5.11). Teaching Tips 1. You might wish to elaborate on the amount of solar energy striking Earth. Every day Earth is bombarded with solar radiation equal to the energy of 100 million atomic bombs. Of the tiny fraction of light that reaches photosynthetic organisms, only about 1% is converted to chemical energy by photosynthesis. 2. Energy coupling at the cellular level may be new to many students, but it is a familiar concept when related to the use of money in our society. Students might be discouraged if the only benefit of work was the ability to make purchases from the employer. (We all might soon tire of a fast-food job that only paid its employees in food!) Money permits the coupling of a generation of value (a paycheck, analogous to an energy-releasing reaction) to an energy-consuming reaction (money, which allows us to make purchases in distant locations). This idea of earning and spending is a common concept we all know well. Copyright © 2009 Pearson Education, Inc.

الارتباط بين البناء الضوئي والتنفس الخلوي
Sunlight energyالطاقة الشمسية The connection between photosynthesis and cellular respiration الارتباط بين البناء الضوئي والتنفس الخلوي ECOSYSTEMالنظام البيئي Photosynthesis in chloroplasts البناء الضوئي في البلاستيدات الخضراء CO2 Glucose + + H2O O2 Cellular respiration in mitochondria التنفس الخلوي في الميتوكوندريا Figure 6.1 The connection between photosynthesis and cellular respiration. ATP (for cellular workللشغل الحيوي ) Heat energyطاقة حرارية

6.2 Breathing supplies oxygen to our cells for use in cellular respiration and removes carbon dioxide يعمل التنفس على تزويد خلايانا بالأوكسجين اللازم لعملية التنفس الخلوي وتحرير ثاني اكسيد الكربون Breathing and cellular respiration are closely related يرتبط التنفس الرئوي والتنفس الخلوي ارتباط وثيقا ببعضهما البعض Breathing is necessary for exchange of CO2 produced during cellular respiration for atmospheric O2 فالتنفس الرئوي ضروري لتبادل ثاني أكسيد الكربون الناتج من التنفس الخلوي بالأوكسجين الجوي Cellular respiration uses O2 to help harvest energy from glucose and produces CO2 in the process يستخدم التنفس الخلوي الاوكسجين للمساعدة في حصد الطاقة من الجلوكوز وإنتاج ثاني أكسيد الكربون في نفس العملية The purpose of cellular respiration is to produce ATP. Student Misconceptions and Concerns 1. Students should be cautioned against the assumption that energy is created when it is converted from one form to another. This might be a good time to review the principle of conservation of energy (the first law of thermodynamics addressed in Module 5.11). Teaching Tips 1. Energy coupling at the cellular level may be new to many students, but it is a familiar concept when related to the use of money in our society. Students might be discouraged if the only benefit of work was the ability to make purchases from the employer. (We all might soon tire of a fast-food job that only paid its employees in food!) Money permits the coupling of a generation of value (a paycheck, analogous to an energy-releasing reaction) to an energy-consuming reaction (money, which allows us to make purchases in distant locations). This idea of earning and spending is a common concept we all know well. Copyright © 2009 Pearson Education, Inc.

التنفس الرئوي تيار الدم تقوم الخلايا العضلية بالتنفس الخلوي
Breathing التنفس الرئوي O2 CO2 Lungsالرئتين CO2 Bloodstream تيار الدم O2 Figure 6.2 The connection between breathing and cellular respiration. تقوم الخلايا العضلية Muscle cells carrying out Cellular Respiration بالتنفس الخلوي Glucose + O2 The connection between breathing and cellular respiration الارتباط بين التنفس الرئوي والتنفس الخلوي CO2 + H2O + ATP

6.3 Cellular respiration banks energy in ATP molecules يخزن التنفس الخلوي الطاقة في جزيئات الـ ATP
Cellular respiration is an exergonic process that transfers energy from the bonds in glucose to ATP التنفس الخلوي هو عملية تفاعل محرر للطاقة والتي تحرر الطاقة المختزنة في روابط جزيء الجلوكوز وتخزينها فيATP Cellular respiration produces 38 ATP molecules from each glucose molecule ينتج التنفس الهوائي 38 جزيء ATP من كل جزيء جلوكوز Other foods (organic molecules) can be used as a source of energy as well يمكن استخدام المواد الغذائية الآخرى (الجزيئات العضوية) كمصدر للطاقة أيضاً Respiration only retrieves 40% of the energy in a glucose molecule. The other 60% of the energy is released as heat. We use this heat to maintain a relatively steady body temperature near 37°C (98–99°F). This is about the same amount of heat generated by a 75-watt incandescent light bulb. Organic compounds possess potential energy as a result of their arrangement of atoms. Compounds that can participate in exergonic reactions can act as food. Actually, cellular respiration includes both aerobic and anaerobic processes. However, it is generally used to refer to the aerobic process. It takes about 10 million ATP molecules per second to power one active muscle cell. Student Misconceptions and Concerns 1. Students should be cautioned against the assumption that energy is created when it is converted from one form to another. This might be a good time to review the principle of conservation of energy (the first law of thermodynamics addressed in Module 5.11). 2. Students often fail to realize that aerobic metabolism is a process generally similar to the burning of wood in a fireplace or campfire or the burning of gasoline in an automobile engine. Noting these general similarities can help students comprehend the overall reaction and heat generation associated with these processes. Teaching Tips 1. Energy coupling at the cellular level may be new to many students, but it is a familiar concept when related to the use of money in our society. Students might be discouraged if the only benefit of work was the ability to make purchases from the employer. (We all might soon tire of a fast-food job that only paid its employees in food!) Money permits the coupling of a generation of value (a paycheck, analogous to an energy-releasing reaction) to an energy-consuming reaction (money, which allows us to make purchases in distant locations). This idea of earning and spending is a common concept we all know well. 2. During cellular respiration, our cells convert about 40% of our food energy to useful work. The other 60% of the energy is released as heat. We use this heat to maintain a relatively steady body temperature near 37°C (98–99°F). This is about the same amount of heat generated by a 75-watt incandescent lightbulb. If you choose to include a discussion of heat generation from aerobic metabolism, consider the following. A. Ask your students why they feel warm when it is 30°C (86°F) outside, if their core body temperature is 37°C (98.6°F). Shouldn’t they feel cold? The answer is, our bodies are always producing heat. At these higher temperatures, we are producing more heat than we need to maintain a body temperature around 37°C. Thus, we sweat and behave in ways that helps us get rid of the extra heat from cellular respiration. B. Share this calculation with your students. Depending upon a person’s size and level of activity, a human might burn 2,000 dietary calories (kilocalories) a day. This is enough energy to raise the temperature of 20 liters of liquid water from 0 to 100°C. This is something to think about the next time you heat water on the stove! (Notes: Consider bringing a 2-liter bottle as a visual aid, or ten 2-liter bottles to make the point above. It takes 100 calories to raise 1 liter of water 100°C; it takes much more energy to melt ice or evaporate water as steam.) Copyright © 2009 Pearson Education, Inc.

Summary equation for cellular respiration ملخص معادلة التنفس الخلوي
C6H12O6 + 6 O2 6 CO2 + 6 H2O + ATPs Glucose جلوكوز Oxygen أوكسجين Carbon dioxide ثاني أكسيد الكربون Water ماء Energy طاقة Figure 6.3 Summary equation for cellular respiration: C6H12O6 + 6 O2 6 CO2 + H2O + energy

6.4 CONNECTION: The human body uses energy from ATP for all its activities رابطة تطبيقية : يستمد جسم الإنسان الطاقة اللازمة لأنشطته المختلفة من ATP The average adult human needs about 2,200 kcal of energy per day يبلغ متوسط ما يحتاجه الإنسان البالغ من السعرات الحرارية حوالي 2,200 سعره حرارية (كيلو كالوري) من الطاقة في اليوم A kilocalorie (kcal) is the quantity of heat required to raise the temperature of 1 kilogram (kg) of water by 1oC السعرة الحرارية (كيلو كالوري) هي كمية الحرارة المطلوبة لرفع درجة حرارة 1 كيلوجرام من الماء درجة مئوية واحدة (ا °م) This energy is used for body maintenance and for voluntary activities تستخدم هذه الطاقة لصيانة الجسم وللأنشطة الإرادية Remember that we are not producing energy in cellular respiration, but rather releasing it from organic molecules. We are simply securing energy that was put in food by photosynthesis. Student Misconceptions and Concerns 1. Students should be cautioned against the assumption that energy is created when it is converted from one form to another. This might be a good time to review the principle of conservation of energy (the first law of thermodynamics addressed in Module 5.11). Teaching Tips 1. You might share with your students that it takes about 10 million ATP molecules per second to power one active muscle cell. Copyright © 2009 Pearson Education, Inc.

النشاط Energy Consumed by Various Activities (in kcal).
الطاقة المستهلكة في انشطة مختلفة (بالكيلو كالوري) الطاقة المستهلكة في انشطة مختلفة (بكيلو كالوري) النشاط الجري (7دقائق / ميل) الرقص (السريع) ركوب الدراجة (10 ميل / ساعة) السباحة (2 ميل / ساعة) المشي (3ميل / ساعة) الرقص (البطيء) الجلوس (الكتابة) * لا تشتمل السعرات المطلوبة في صيانة الجسد الكيلو كالوري المستهلك في الساعة بواسطة شخص يزن 67,5 كجم (150 رطل) * Table 6.4 Energy Consumed by Various Activities (in kcal).

An important question is how do cells extract this energy?
6.5 Cells tap energy from electrons “falling” from organic fuels to oxygen تستخلص الخلايا الطاقة من الإليكترونات ”الهابطة“ من الوقود العضوي للأوكسجين The energy necessary for life is contained in the arrangement of electrons in chemical bonds in organic molecules الطاقة اللازمة للحياة توجد في منظومة اليكترونات الروابط الكيميائية في الجزيئات العضوية An important question is how do cells extract this energy? سؤال هام : كيف تستخلص الخلايا هذه الطاقة؟ When the carbon-hydrogen bonds of glucose are broken, electrons are transferred to oxygen عندما تنكسر روابط الكربون بالهيدروجين في الجلوكوز ، تنتقل الإليكترونات للأوكسجين Oxygen has a strong tendency to attract electrons هناك نزعة قوية في الأوكسجين لجذب الإليكترونات Energy must be added to pull an electron away from an atom, just as energy is required to push a ball uphill. Student Misconceptions and Concerns 1. Students should be cautioned against the assumption that energy is created when it is converted from one form to another. This might be a good time to review the principle of conservation of energy (the first law of thermodynamics addressed in Module 5.11). 2. The advantage of the gradual degradation of glucose may not be obvious to some students. Many analogies exist that reveal the advantages of short and steady steps. Fuel in an automobile is burned slowly to best utilize the energy released from the fuel. A few fireplace logs release gradual heat to keep a room temperature steady. In both situations, excessive use of fuel becomes wasteful, reducing the efficiencies of the systems. Copyright © 2009 Pearson Education, Inc.

6.5 Cells tap energy from electrons “falling” from organic fuels to oxygen تستخلص الخلايا الطاقة من الإليكترونات ”الهابطة“ من الوقود العضوي للأوكسجين A cellular respiration equation is helpful to show the changes in hydrogen atom distribution معادلة التنفس الخلوي مفيدة لبيان التغيرات التي تطرأ على توزيع ذرة الهيدروجين Glucose loses its hydrogen atoms and is ultimately converted to CO2 يفقد الجلوكوز ذرات الهيدروجين ويتحول في النهاية لثاني أكسيد الكربون At the same time, O2 gains hydrogen atoms and is converted to H2O زفي نفس الوقت يتحد الأوكسجين مع ذرات الهيدروجين ويتحول لماء Loss of electrons is called oxidationتسمى فقدان الإليكترونات بالأكسدة Gain of electrons is called reductionيسمى اكتساب الإليكترونان بالاختزال The movement of electrons is called an oxidation-reduction or redox reaction. The combustion of gasoline in an automobile engine is also a redox reaction: the energy released pushes the pistons. Our main energy foods are carbohydrates and fats because they are reservoirs of large numbers of electrons associated with hydrogen. You may want to tell your students that a hydrogen atom consists of an electron and a proton, and although we have only considered the electron up to now, the proton becomes important later in the synthesis of ATP. Student Misconceptions and Concerns 1. Students should be cautioned against the assumption that energy is created when it is converted from one form to another. This might be a good time to review the principle of conservation of energy (the first law of thermodynamics addressed in Module 5.11). 2. The advantage of the gradual degradation of glucose may not be obvious to some students. Many analogies exist that reveal the advantages of short and steady steps. Fuel in an automobile is burned slowly to best utilize the energy released from the fuel. A few fireplace logs release gradual heat to keep a room temperature steady. In both situations, excessive use of fuel becomes wasteful, reducing the efficiencies of the systems. Copyright © 2009 Pearson Education, Inc.

طاقة (ATP) Glucose جلوكوز
Rearrangement of hydrogen atoms (with their electrons) in the redox reactions of cellular respiration إعادة ترتيب ذرات الهيدروجين (بإليكتروناتها) في تفاعل إخسدة التنفس الخلوي Loss of hydrogen atoms فقدان ذرات الهيدروجين (oxidationالأكسدة ) C6H12O O2 6 CO H2O Energy طاقة (ATP) Glucose جلوكوز Gain of hydrogen atoms اكتساب ذرات الهيدروجين (reductionاختزال ) Figure 6.5A Rearrangement of hydrogen atoms (with their electrons) in the redox reactions of cellular respiration.

Enzymes are necessary to oxidize glucose and other foods
6.5 Cells tap energy from electrons “falling” from organic fuels to oxygen تستخلص الخلايا الطاقة من الإليكترونات ”الهابطة“ من الوقود العضوي للأوكسجين Enzymes are necessary to oxidize glucose and other foods الإنزيمات ضرورية لأكسدة الجلوكوز والأغذية الأخرى The enzyme that removes hydrogen from an organic molecule is called dehydrogenase يسمى الإنزيم الذي يزيل الهيدروجين من الجزيء العضوي بالديهايدروجينيز (انزيم نزع الهيدروجين) Dehydrogenase requires a coenzyme called NAD+ (nicotinamide adenine dinucleotide) to shuttle electrons يتطلب الديهايدروجينيز مرافق إنزيمي يسمى بـ NAD+ (نيوكليتيدة الأدنين نيكوتين أميد الثنائية) لنقل الالكترونات NAD+ can become reduced when it accepts electrons and oxidized when it gives them up يصبح الـ NAD+ مُختِزَلا عندما يستقبل اليكترونات ويصبح مُؤَكسد عندما يفقدها Students should probably be reminded that the -ase on a word indicates an enzyme and that often the word is descriptive of the enzyme’s activity. NAD+ is a derivative of the vitamin niacin. Student Misconceptions and Concerns 1. Students should be cautioned against the assumption that energy is created when it is converted from one form to another. This might be a good time to review the principle of conservation of energy (the first law of thermodynamics addressed in Module 5.11). 2. The advantage of the gradual degradation of glucose may not be obvious to some students. Many analogies exist that reveal the advantages of short and steady steps. Fuel in an automobile is burned slowly to best utilize the energy released from the fuel. A few fireplace logs release gradual heat to keep a room temperature steady. In both situations, excessive use of fuel becomes wasteful, reducing the efficiencies of the systems. Copyright © 2009 Pearson Education, Inc.

Oxidationأكسدة Reductionاختزال
pair of redox reactions, occurring simultaneously زوج من تفاعلات الأخسدة يحدثان في آن واحد Oxidationأكسدة Dehydrogenase ديهايدروجينيز Reductionاختزال NAD+ + 2 H NADH + H+ Figure 6.5B A pair of redox reactions, occurring simultaneously. (carries 2 electrons) (يحمل اليكترونيين) 2 H e–

6.5 Cells tap energy from electrons “falling” from organic fuels to oxygen تستخلص الخلايا الطاقة من الإليكترونات ”الهابطة“ من الوقود العضوي للأوكسجين The transfer of electrons to NAD+ results in the formation of NADH, the reduced form of NAD+ انتقال الإليكترونات إلى NAD+ يؤدي لتكوين NADH (الصيغة المختزلة لـ NAD+) In this situation, NAD+ is called an electron acceptor, but it eventually becomes oxidized (loses an electron) and is then called an electron donor ويسمى في هذه الحالة الـ NAD+ مستقبل اليكتروني ، ولكنه في النهاية يصبح مُؤكسداً (يفقد اليكتروناً) وعندها يسمى واهب اليكتروني Electrons are removed, transferred, and accepted in pairs. Student Misconceptions and Concerns 1. Students should be cautioned against the assumption that energy is created when it is converted from one form to another. This might be a good time to review the principle of conservation of energy (the first law of thermodynamics addressed in Module 5.11). 2. The advantage of the gradual degradation of glucose may not be obvious to some students. Many analogies exist that reveal the advantages of short and steady steps. Fuel in an automobile is burned slowly to best utilize the energy released from the fuel. A few fireplace logs release gradual heat to keep a room temperature steady. In both situations, excessive use of fuel becomes wasteful, reducing the efficiencies of the systems. Copyright © 2009 Pearson Education, Inc.

There are other electron “carrier” molecules that function like NAD+
6.5 Cells tap energy from electrons “falling” from organic fuels to oxygen تستخلص الخلايا الطاقة من الإليكترونات ”الهابطة“ من الوقود العضوي للأوكسجين There are other electron “carrier” molecules that function like NAD+ يوجد جزيئات أخرى ”حاملة“ للإليكترون تعمل مثل NAD+ They form a staircase where the electrons pass from one to the next down the staircase تنتظم هذه الجزيئات على هيئة سلم حيث يتدرج الإليكترون في النزول من درجة الى اخرى These electron carriers collectively are called the electron transport chain, and as electrons are transported down the chain, ATP is generated تسمى هذه الحوامل جملةً سلسلة النقل الإليكتروني ، و بانتقال الاليكترونات باتجاه أسفل السلسلة يتولد الـ ATP Electron transport occurs in the cell’s inner membrane of a mitochondrion. The final electron acceptor is oxygen, and the product of this reaction is water. Student Misconceptions and Concerns 1. Students should be cautioned against the assumption that energy is created when it is converted from one form to another. This might be a good time to review the principle of conservation of energy (the first law of thermodynamics addressed in Module 5.11). 2. The advantage of the gradual degradation of glucose may not be obvious to some students. Many analogies exist that reveal the advantages of short and steady steps. Fuel in an automobile is burned slowly to best utilize the energy released from the fuel. A few fireplace logs release gradual heat to keep a room temperature steady. In both situations, excessive use of fuel becomes wasteful, reducing the efficiencies of the systems. Copyright © 2009 Pearson Education, Inc.

سلسلة النقل الإليكتروني
ATP NAD+ NADH H+ 2e– Electron transport سلسلة النقل الإليكتروني chain Controlled release of energy for synthesis of ATP + O2 H2O 1  2 In cellular respiration, electrons fall down an energy staircase and finally reduce O2 في التنفس الخلوي تتدرج الإليكترونات في الانتقال باتجاه أسفل سلم الطاقة وتختزل في النهاية الأوكسجين مكونة الماء تحرير منظم للطاقة لتكوين الـ ATP Figure 6.5C In cellular respiration, electrons fall down an energy staircase and finally reduce O2.

STAGES OF CELLULAR RESPIRATION AND FERMENTATION
مراحل التنفس الخلوي والتخمر Copyright © 2009 Pearson Education, Inc.

Stage 1: Glycolysisالمرحلة 1: تحلل الجلوكوز
6.6 Overview: Cellular respiration occurs in three main stages نظرة شاملة : يحدث التنفس الخلوي على ثلاث مراحل رئيسية Stage 1: Glycolysisالمرحلة 1: تحلل الجلوكوز Glycolysis begins respiration by breaking glucose, a six-carbon molecule, into two molecules of a three-carbon compound called pyruvate تبدأ عملية التنفس بتحليل الجلوكوز (جزيء سداسي الكربون) إلى جزيئين من مركب ثلاثي الكربون يسمى بالبايروفيت This stage occurs in the cytoplasm تحدث هذه المرحلة في السيتوبلازم Glucose C-C-C-C-C-C C-C-C C-C-C Glycolysis In Cytoplasm The term glycolysis means “splitting of sugar.” Student Misconceptions and Concerns 1. Perhaps more than anywhere else in general biology, students studying aerobic metabolism may fail to see the forest for the trees. Students may focus on the details of each stage of aerobic metabolism and devote little attention to the overall process and products. Consider emphasizing the products and energy yields associated with glycolysis, the citric acid cycle, and oxidative phosphorylation before detailing the specifics of each reaction. 2. The location within a cell in which each reaction takes place is often forgotten in the details of the chemical processes, but it is important to emphasize. Consider using Figure 6.12 as a common reference to locate each stage as you discuss the details of cellular respiration. 3. Students frequently think that plants have chloroplasts instead of mitochondria. Take care to point out the need for mitochondria in plants when photosynthesis is not efficient or possible (such as during the night). Pyruvate Pyruvate Copyright © 2009 Pearson Education, Inc.

An overview of glycolysis نظرة شاملة لتحلل الجلوكوز
Glucoseجلوكوز NAD+ + 2 2 ADP NADH P ATP H+ 2 Pyruvate 2 بايروفيت 6.7 Glycolysis harvests chemical energy by oxidizing glucose to pyruvate تحصد عملية تحلل الجلوكوز الطاقة الكيميائية بأكسدة الجلوكوز إلى بايروفيت In glycolysis, a single molecule of glucose is enzymatically cut in half through a series of steps to produce two molecules of pyruvate في عملية تحلل الجلوكوز يقطع جزيء واحد من الجلوكوز إنزيمياً إلى نصفين خلال سلسلة من الخطوات لإنتاج جزيئين من البايروفيت In the process, two molecules of NAD+ are reduced to two molecules of NADH في هذه العملية يختزل جزيئان منNAD+ إلى جزيئين من NADH At the same time, two molecules of ATP are produced by substrate-level phosphorylation ينتج في نفس الوقت جزيئان من ATP بواسطة فسفرة مستوى عامل الانزيم Figure 6.7A An overview of glycolysis. An overview of glycolysis نظرة شاملة لتحلل الجلوكوز

Stage 2: The citric acid cycle المرحلة 2: دورة حامض الستريك
6.6 Overview: Cellular respiration occurs in three main stages نظرة شاملة : يحدث التنفس الخلوي على ثلاث مراحل رئيسية Stage 2: The citric acid cycle المرحلة 2: دورة حامض الستريك The citric acid cycle breaks down pyruvate into carbon dioxide and supplies the third stage with electrons تحلل دورة حمض الستريك البايروفيت إلى ثاني أكسيد الكربون وتزود المرحلة الثالثة بالإليكترونات This stage occurs in the mitochondria تحدث هذه المرحلة في الميتوكوندريا Citric Acid Cycle Pyruvate Electrons Mitochondria CO2 The citric acid cycle has eight steps, each catalyzed by a particular enzyme. Student Misconceptions and Concerns 1. Perhaps more than anywhere else in general biology, students studying aerobic metabolism may fail to see the forest for the trees. Students may focus on the details of each stage of aerobic metabolism and devote little attention to the overall process and products. Consider emphasizing the products and energy yields associated with glycolysis, the citric acid cycle, and oxidative phosphorylation before detailing the specifics of each reaction. 2. The location within a cell in which each reaction takes place is often forgotten in the details of the chemical processes, but it is important to emphasize. Consider using Figure 6.12 as a common reference to locate each stage as you discuss the details of cellular respiration. 3. Students frequently think that plants have chloroplasts instead of mitochondria. Take care to point out the need for mitochondria in plants when photosynthesis is not efficient or possible (such as during the night). Copyright © 2009 Pearson Education, Inc.

Electron Transport Chain
6.6 Overview: Cellular respiration occurs in three main stages نظرة شاملة : يحدث التنفس الخلوي على ثلاث مراحل رئيسية Stage 3: Oxidative phosphorylationالمرحلة 3: الفسفرة المؤكسِدة At this stage, electrons are shuttled through the electron transport chain خلال هذه المرحلة تنتقل الإليكترونات عبر سلسلة النقل الإليكتروني As a result, ATP is generated through oxidative phosphorylation associated with chemiosmosis ونتيجة لذلك يتولد الـ ATP من خلال الفسفرة المؤكسٍدة المرتبطة بالإسموزية الكيميائية This stage occurs in the inner mitochondrion membrane تحدث هذه المرحلة في الغشاء الداخلي للميتوكوندريا Pyruvate Citric Acid Cycle Electrons CO2 Electron Transport Chain O2 H2O ATP Oxidative Phosphorylation Mitochondria Chemiosmosis Many of the electron carriers in the electron transport are proteins called cytochromes that have an important component called heme that has an iron atom that accepts and donates electrons. Student Misconceptions and Concerns 1. Perhaps more than anywhere else in general biology, students studying aerobic metabolism may fail to see the forest for the trees. Students may focus on the details of each stage of aerobic metabolism and devote little attention to the overall process and products. Consider emphasizing the products and energy yields associated with glycolysis, the citric acid cycle, and oxidative phosphorylation before detailing the specifics of each reaction. 2. The location within a cell in which each reaction takes place is often forgotten in the details of the chemical processes, but it is important to emphasize. Consider using Figure 6.12 as a common reference to locate each stage as you discuss the details of cellular respiration. 3. Students frequently think that plants have chloroplasts instead of mitochondria. Take care to point out the need for mitochondria in plants when photosynthesis is not efficient or possible (such as during the night). Copyright © 2009 Pearson Education, Inc.

An overview of cellular respiration نظرة شاملة للتنفس الخلوي
Mitochondrion ميتوكوندريا CO2 NADH ATP High-energy electrons carried by NADH اليكترونات ذات طاقة عالية محمولة على NADH CITRIC ACID CYCLE دورة جامض الستريك GLYCOLYSISتحلل الجلوكوز Pyruvate بايروفيت Glucose جلوكوز and FADH2 Substrate-level phosphorylation فسفرة مستوى عامل الإنزيم OXIDATIVE PHOSPHORYLATION (Electron Transport and Chemiosmosis) فسفرة مؤكسدة (النقل الاليكتروني والإسموزية الكيميائية) Oxidative phosphorylation فسفرة مؤكسدة Cytoplasm سيتوبلازم Inner mitochondrial Membrane غشاء الميتوكوندريا الداخلي An overview of cellular respiration نظرة شاملة للتنفس الخلوي Figure 6.6 An overview of cellular respiration.

6.13 Fermentation enables cells to produce ATP without oxygen يجعل التخمر الخلايا قادرة على انتاج ATP دون الحاجة الى الأوكسجين Fermentation is an anaerobic (without oxygen) energy-generating process التخمر هو عملية توليد الطاقة لا هوائيا (دون الحاجة لأوكسجين) It takes advantage of glycolysis, producing two ATP molecules and reducing NAD+ to NADH يستفيد من التحلل الجلوكوزي بإنتاج جزيئين ATP واختزال NAD+ إلى NADH The trick is to oxidize the NADH without passing its electrons through the electron transport chain to oxygen تكمن الفكرة في أكسدة NADH دون تمرير اليكتروناته خلال سلسلة النقل الاليكتروني للأوكسجين Fermentation captures significantly less energy from a glucose molecule than is captured from glucose through respiration. Student Misconceptions and Concerns 1. Perhaps more than anywhere else in general biology, students studying aerobic metabolism may fail to see the forest for the trees. Students may focus on the details of each stage of aerobic metabolism and devote little attention to the overall process and products. Consider emphasizing the products and energy yields associated with glycolysis, the citric acid cycle, and oxidative phosphorylation before detailing the specifics of each reaction. 2. The location within a cell in which each reaction takes place is often forgotten in the details of the chemical processes, but it is important to emphasize. Consider using Figure 6.12 as a common reference to locate each stage as you discuss the details of cellular respiration. 3. Students frequently think that plants have chloroplasts instead of mitochondria. Take care to point out the need for mitochondria in plants when photosynthesis is not efficient or possible (such as during the night). 4. Students may expect that fermentation will produce alcohol and maybe even carbon dioxide. Take the time to clarify the different possible products of fermentation and correct this general misconception. Teaching Tips 1. The text notes that some microbes are useful in the dairy industry because they produce lactic acid. However, the impact of acids on milk may not be obvious to many students. Consider a simple demonstration mixing about equal portions of milk (skim or 2%) with some acid (vinegar will work). Notice the accumulation of strands of milk curd (protein) on the side of the container and stirring device. 2. Dry wines are produced when the yeast cells use up all or most of the sugar available. Sweet wines result when the alcohol accumulates enough to inhibit fermentation before the sugar is depleted. 3. Exposing fermenting yeast to oxygen will slow or stop the process, because the yeast will switch back to aerobic respiration. When fermentation is rapid, the carbon dioxide produced drives away the oxygen immediately above the wine. However, as fermentation slows down, the wine must be sealed to prevent oxygen exposure and permit the fermentation process to finish. Copyright © 2009 Pearson Education, Inc.

Animation: Fermentation Overview
6.13 Fermentation enables cells to produce ATP without oxygen يجعل التخمر الخلايا قادرة على انتاج ATP دون الحاجة الى الأوكسجين Your muscle cells and certain bacteria can oxidize NADH through lactic acid fermentation يمكن أن تؤكسد خلاياك العضلية وبعض أنواع البكتيريا مركب الـ NADH من خلال تخمر الحامض اللبني NADH is oxidized to NAD+ when pyruvate is reduced to lactate يتأكسد الـ NADH إلى NAD+ عندما يختزل البايروفيت إلى اللاكتيت In a sense, pyruvate is serving as an “electron sink,” a place to dispose of the electrons generated by oxidation reactions in glycolysis بمعنى ان يعمل البايروفيت ”كحوض اليكتروني“ ، مكان تلقى فيه الإليكترونات الناتجة من تفاعلات الأكسدة في تحلل الجلوكوز Fermentations are used by the dairy industry to make cheese and yogurt, while other industries produce soy sauce and sauerkraut through fermentation reactions. Student Misconceptions and Concerns 1. Perhaps more than anywhere else in general biology, students studying aerobic metabolism may fail to see the forest for the trees. Students may focus on the details of each stage of aerobic metabolism and devote little attention to the overall process and products. Consider emphasizing the products and energy yields associated with glycolysis, the citric acid cycle, and oxidative phosphorylation before detailing the specifics of each reaction. 2. The location within a cell in which each reaction takes place is often forgotten in the details of the chemical processes, but it is important to emphasize. Consider using Figure 6.12 as a common reference to locate each stage as you discuss the details of cellular respiration. 3. Students frequently think that plants have chloroplasts instead of mitochondria. Take care to point out the need for mitochondria in plants when photosynthesis is not efficient or possible (such as during the night). 4. Students may expect that fermentation will produce alcohol and maybe even carbon dioxide. Take the time to clarify the different possible products of fermentation and correct this general misconception. Teaching Tips 1. The text notes that some microbes are useful in the dairy industry because they produce lactic acid. However, the impact of acids on milk may not be obvious to many students. Consider a simple demonstration mixing about equal portions of milk (skim or 2%) with some acid (vinegar will work). Notice the accumulation of strands of milk curd (protein) on the side of the container and stirring device. 2. Dry wines are produced when the yeast cells use up all or most of the sugar available. Sweet wines result when the alcohol accumulates enough to inhibit fermentation before the sugar is depleted. 3. Exposing fermenting yeast to oxygen will slow or stop the process, because the yeast will switch back to aerobic respiration. When fermentation is rapid, the carbon dioxide produced drives away the oxygen immediately above the wine. However, as fermentation slows down, the wine must be sealed to prevent oxygen exposure and permit the fermentation process to finish. Animation: Fermentation Overview Copyright © 2009 Pearson Education, Inc.

GLYCOLYSISتحلل جلوكوزي Lactic acid fermentation
Glucoseجلوكوز 2 NAD+ 2 ADP  2 P GLYCOLYSISتحلل جلوكوزي 2 ATP 2 NADH Lactic acid fermentation تخمر الحامض اللبني 2 Pyruvate2 بايروفيت 2 NADH Figure 6.13A Lactic acid fermentation oxidizes NADH to NAD+ and produces lactate. 2 NAD+ 2 Lactate2 لاكتيت

6.13 Fermentation enables cells to produce ATP without oxygen يجعل التخمر الخلايا قادرة على انتاج ATP دون الحاجة الى الأوكسجين The baking and winemaking industry have used alcohol fermentation for thousands of years تم استخدام التخمر الكحولي في صناعة الخبز ووفي صناعة النبيذ لآلاف السنين Yeasts are single-celled fungi that not only can use respiration for energy but can ferment under anaerobic conditions الخمائر هي فطريات وحيدة الخلية ، الى جانب انها تستطيع القيام بالتنفس الخلوي (هوائيا) لإنتاج الطاقة فهي قادرة على القيام بعملية التخمر تحت الظروف اللاهوائية They convert pyruvate to CO2 and ethanol while oxidizing NADH back to NAD+ تحول الخمائر البايروفيت لثاني أكسيد الكربون وكحول إيثيلي بينما تقوم بأكسدة الـ NADH إلى NAD+ The carbon dioxide provides the bubbles in beer and champagne and also the bubbles in dough that cause bread to rise. Student Misconceptions and Concerns 1. Perhaps more than anywhere else in general biology, students studying aerobic metabolism may fail to see the forest for the trees. Students may focus on the details of each stage of aerobic metabolism and devote little attention to the overall process and products. Consider emphasizing the products and energy yields associated with glycolysis, the citric acid cycle, and oxidative phosphorylation before detailing the specifics of each reaction. 2. The location within a cell in which each reaction takes place is often forgotten in the details of the chemical processes, but it is important to emphasize. Consider using Figure 6.12 as a common reference to locate each stage as you discuss the details of cellular respiration. 3. Students frequently think that plants have chloroplasts instead of mitochondria. Take care to point out the need for mitochondria in plants when photosynthesis is not efficient or possible (such as during the night). 4. Students may expect that fermentation will produce alcohol and maybe even carbon dioxide. Take the time to clarify the different possible products of fermentation and correct this general misconception. Teaching Tips 1. The text notes that some microbes are useful in the dairy industry because they produce lactic acid. However, the impact of acids on milk may not be obvious to many students. Consider a simple demonstration mixing about equal portions of milk (skim or 2%) with some acid (vinegar will work). Notice the accumulation of strands of milk curd (protein) on the side of the container and stirring device. 2. Dry wines are produced when the yeast cells use up all or most of the sugar available. Sweet wines result when the alcohol accumulates enough to inhibit fermentation before the sugar is depleted. 3. Exposing fermenting yeast to oxygen will slow or stop the process, because the yeast will switch back to aerobic respiration. When fermentation is rapid, the carbon dioxide produced drives away the oxygen immediately above the wine. However, as fermentation slows down, the wine must be sealed to prevent oxygen exposure and permit the fermentation process to finish. Copyright © 2009 Pearson Education, Inc.

تخمر الكحول Alcohol fermentation Glucoseجلوكوز 2 ADP 2 NAD+  2 P 2
GLYCOLYSIS 2 ATP 2 NADH Alcohol fermentation تخمر الكحول 2 Pyruvate2 بايروفيت 2 NADH 2 CO2 Released تحرير CO2 Figure 6.13B Alcohol fermentation oxidizes NADH to NAD+ and produces ethanol and CO2. 2 NAD+ 2 Ethanol2 إيثانول

الترابط بين هدم وبناء الجزيئات
INTERCONNECTIONS BETWEEN MOLECULAR BREAKDOWN AND SYNTHESIS الترابط بين هدم وبناء الجزيئات Copyright © 2009 Pearson Education, Inc.

6.15 Cells use many kinds of organic molecules as fuel for cellular respiration تستخدم الخلايا العديد من المركبات العضوية كوقود للتنفس الهوائي Although glucose is considered to be the primary source of sugar for respiration and fermentation, there are actually three sources of molecules for generation of ATP بالرغم من اعتبار الجلوكوز مصدر السكر الرئيسي للتنفس والتخمر ، إلا أنه يوجد ثلاثة مصادر جزيئية أخرى لتوليد الـ ATP Carbohydrates (disaccharides)الكربوهيدرات (السكريات الثنائية) Proteins (after conversion to amino acids)البروتينات (بعد التحول لأحماض أمينيه) Fatsالدهون Teaching Tips 1. The same mass of fat stores nearly twice as many calories (about 9 kcal per gram) as an equivalent mass of protein or carbohydrates (about 4.5–5 kcal per gram). Fat is therefore an efficient way to store energy in animals and many plants. To store an equivalent amount of energy in the form of carbohydrates or proteins would require about twice the mass, adding a significant burden to the organism’s structure. (For example, if you were 20 lbs overweight, you would be nearly 40 lbs overweight if the same energy were stored as carbohydrates or proteins instead of fat). 2. Figure 6.15 is an important visual synthesis of the diverse fuels that can enter into cellular respiration and the various stages of this process. Figures such as this can serve as a visual anchor to integrate the many aspects of this chapter. 3. The final modules in this chapter may raise questions about obesity and proper diet. The Centers for Disease Control and Prevention website, discusses many aspects of nutrition, obesity, and general physical fitness and is a useful reference for teachers and students. Copyright © 2009 Pearson Education, Inc.

Pathways that break down various food molecules
Food, such as peanuts الغذاء ، مثل الفول السوداني Carbohydrates الكربوهيدرات Fatsالدهون Proteinsالبروتينات Sugarsسكاكر Glycerol جليسيرول Fatty acidsأحماض دهنية Amino acidsأحماض امينية Amino groups مجاميع أمينية Figure 6.15 Pathways that break down various food molecules. OXIDATIVE PHOSPHORYLATION (Electron Transport and Chemiosmosis) الفسفرة المؤكسدة (النقل الإليكتروني والإسموزية الكيميائية) Glucose جلوكوز Pyruvate بايروفيت Acetyl CoA خلات مرافق الإنزيم A CITRIC ACID CYCLE دورة حامض السيتريك G3P GLYCOLYSISالتحلل الجلوكوزي ATP Pathways that break down various food molecules مسارات هدم جزيئات الغذاء المختلفة

Chapter 7 الباب السابع Photosynthesis: Using Light to Make Food
البناء الضوئي : استخدام الضوء لصنع الغذاء Lecture by Richard L. Myers Translated by Nabih A. Baeshen

Introduction: Plant Power مقدمة : قوة النبات
Plants use water and atmospheric carbon dioxide to produce a simple sugar and liberate oxygen تستخدم النباتات الماء وثاني الكربون الجوي لينتج سكر بسيط وأوكسجين Earth’s plants produce 160 billion metric tons of sugar each year through photosynthesis, a process that converts solar energy to chemical energy تنتج نباتات الأرض 160 مليار طن من السكر كل سنة بالبناء الضوئي ، وهو عملية تحول الطاقة الشمسية إلى طاقة كيميائية Sugar is food for humans and for animals that we consume السكر غذاء يستهلكه كل من الإنسان والحيوان Photosynthesis nourishes almost the entire living world directly or indirectly. Almost all plants are autotrophs, meaning that they sustain themselves without eating anything derived from other living beings. Plants produce oxygen, a by-product of photosynthesis, that is used in respiration. The solar energy used in photosynthesis traveled 150 million kilometers from the sun to Earth to be converted into chemical energy. You may want to reintroduce the terms producers and consumers within the context of this chapter. Carbon dioxide ثاني اكسيد الكربون C6H12O6 Photosynthesis البناء الضوئي H2O CO2 O2 Water + 6 6 Light energy Oxygen gas غاز الاكسجين Glucose جلوكوز + 6 الطاقة الضوئية Copyright © 2009 Pearson Education, Inc.

AN OVERVIEW OF PHOTOSYNTHESIS نظرة شاملة للبناء الضوئي

Kelp, a large algaeالكيلب طحلب كبير
7.1 Autotrophs are the producers of the biosphere الكائنات ذاتية التغذية هي منتجات الغلاف الحيوي Autotrophs are living things that are able to make their own food without using organic molecules derived from any other living thing الكائنات ذاتية التغذية هي كائنات حية قادرة على تصنيع غذائها دون استخدام جزيئات عضوية مستمدة من أي كائن حي آخر Autotrophs that use the energy of light to produce organic molecules are called photoautotrophs تسمى الكائنات ذاتية التغذية التي تستخدم طاقة الضوء لتنتج جزيئات عضوية بالكائنات ذاتية التغذية الضوئية Most plants, algae and other protists, and some prokaryotes are photoautotrophs معظم النباتات والطحالب والأوليات الأخرى وبعض أوليات النواة هي ذاتية التغذية الضوئية A very interesting class of autotrophs are the autotrophic bacteria that use carbon dioxide to synthesize organic molecules without solar energy. Teaching Tips 1. When introducing the diverse ways that plants impact our lives, consider challenging your students to come up with a list of products made from plants that they come across on a regular basis. The collective lists from your students can be surprisingly long and might help to build up your catalog of examples. 2. The evolution of chloroplasts from photosynthetic prokaryotes living inside of eukaryotic cells is briefly noted in a reference to Module If your students have not already read Chapter 4, consider discussing the evidence that suggests this endosymbiotic origin. 3. Some students might think that the term producers applies to the production of oxygen by plants. In turn, they might think that consumers are organisms that use oxygen (which would include all aerobic organisms). Extra care may be needed to clarify the definitions of these frequently used terms. Kelp, a large algaeالكيلب طحلب كبير Copyright © 2009 Pearson Education, Inc.

المقدرة على البناء الضوئي مرتبطة مباشرة بتركيب البلاستيدات الخضراء
7.1 Autotrophs are the producers of the biosphere الكائنات ذاتية التغذية هي منتجات الغلاف الحيوي The ability to photosynthesize is directly related to the structure of chloroplasts المقدرة على البناء الضوئي مرتبطة مباشرة بتركيب البلاستيدات الخضراء Chloroplasts are organelles consisting of photosynthetic pigments, enzymes, and other molecules grouped together in membranes البلاستيدات الخضراء هي عضيات تتكون من صبغات مكونة للضوء وإنزيمات ومركبات أخرى مجموعة مع بعضها البعض في أغشية There are about half a million chloroplasts per square millimeter of leaf surface. Chloroplast membranes are similar to mitochondrial membranes in that both are important in energy-harvesting duties of the cell. Teaching Tips 1. When introducing the diverse ways that plants impact our lives, consider challenging your students to come up with a list of products made from plants that they come across on a regular basis. The collective lists from your students can be surprisingly long and might help to build up your catalog of examples. 2. The evolution of chloroplasts from photosynthetic prokaryotes living inside of eukaryotic cells is briefly noted in a reference to Module If your students have not already read Chapter 4, consider discussing the evidence that suggests this endosymbiotic origin. 3. Some students might think that the term producers applies to the production of oxygen by plants. In turn, they might think that consumers are organisms that use oxygen (which would include all aerobic organisms). Extra care may be needed to clarify the definitions of these frequently used terms. Micrograph of cyanobacteria (photosynthetic bacteria) صورة بالمجهر الضوئي للسيانوبكتيريا (بكتيريا تقوم بعملية البناء الضوئي) Copyright © 2009 Pearson Education, Inc.

يلعب الكلوروفيل دوراً هاماً في تحويل الطاقة الشمسية إلى طاقة كيميائية
7.2 Photosynthesis occurs in chloroplasts in plant cells يحدث البناء الضوئي في البلاستيدات الخضراء في الخلايا النباتية Chloroplasts are the major sites of photosynthesis in green plants البلاستيدات الخضراء هي المواقع الرئيسية للبناء الضوئي في النباتات الخضراء Chlorophyll, an important light absorbing pigment in chloroplasts, is responsible for the green color of plants الكلوروفيل صبغة هامة لامتصاص الضوء في البلاستيدات الخضراء وهي المسئولة عن اللون الاخضر في النبات ا Chlorophyll plays a central role in converting solar energy to chemical energy يلعب الكلوروفيل دوراً هاماً في تحويل الطاقة الشمسية إلى طاقة كيميائية Chlorophyll absorbs light energy and drives the synthesis of organic molecules. Teaching Tips 1. The authors note the analogous roles of the thylakoid space and the intermembrane space of a mitochondrion. Students might be encouraged to create a list of the similarities in structure and function of mitochondria and chloroplasts through these related chapters. 2. The living world contains many examples of adaptations to increase surface area. Some examples are the many folds of the inner mitochondrial membrane, the highly branched surfaces of fish gills and human lungs, and the highly branched system of capillaries in the tissues of our bodies. Consider relating this broad principle to the extensive folding of the thylakoid membranes. Copyright © 2009 Pearson Education, Inc.

Veins in the leaf deliver water absorbed by roots
7.2 Photosynthesis occurs in chloroplasts in plant cells يحدث البناء الضوئي في البلاستيدات الخضراء في الخلايا النباتية Chloroplasts are concentrated in the cells of the mesophyll, the green tissue in the interior of the leaf تتركز البلاستيدات الخضراء في خلايا الميزوفيل (النسيج الوسطي)وهي النسيج الأخضر في مقدمة الورقة Stomata are tiny pores in the leaf that allow carbon dioxide to enter and oxygen to exit الثغور هي فتحات صغيرة في الورقة تسمح بدخول ثاني أوكسيد الكربون وخروج الأوكسجين Veins in the leaf deliver water absorbed by roots توصل العروق التي في الأوراق الماء الممتص بواسطة الجذور Leaves also use veins to export sugar to roots and other nonphotosynthetic parts of the plant. Teaching Tips 1. The authors note the analogous roles of the thylakoid space and the intermembrane space of a mitochondrion. Students might be encouraged to create a list of the similarities in structure and function of mitochondria and chloroplasts through these related chapters. 2. The living world contains many examples of adaptations to increase surface area. Some examples are the many folds of the inner mitochondrial membrane, the highly branched surfaces of fish gills and human lungs, and the highly branched system of capillaries in the tissues of our bodies. Consider relating this broad principle to the extensive folding of the thylakoid membranes. Copyright © 2009 Pearson Education, Inc.

7.2 Photosynthesis occurs in chloroplasts in plant cells يحدث البناء الضوئي في البلاستيدات الخضراء في الخلايا النباتية An envelope of two membranes encloses the stroma, the dense fluid within the chloroplast تغلف الحشوة (السائل الكثيف في البلاستيدات الخضراء) بغلاف من غشائيين A system of interconnected membranous sacs called thylakoids segregates the stroma from another compartment, the thylakoid space القريصات هي منظومة من الأكياس الغشائية المتداخلة والتي تفصل الحشوة عن جزء آخر وهو الحيز القريصي Thylakoids are concentrated in stacks called grana تنتظم القريصات فوق بعضها البعض مشكلة وحدات متراصة يسمى كل منها بالكيس القريصي او الحبيبة (Granam ) Chlorophyll resides in the thylakoid membranes. Teaching Tips 1. The authors note the analogous roles of the thylakoid space and the intermembrane space of a mitochondrion. Students might be encouraged to create a list of the similarities in structure and function of mitochondria and chloroplasts through these related chapters. 2. The living world contains many examples of adaptations to increase surface area. Some examples are the many folds of the inner mitochondrial membrane, the highly branched surfaces of fish gills and human lungs, and the highly branched system of capillaries in the tissues of our bodies. Consider relating this broad principle to the extensive folding of the thylakoid membranes. Copyright © 2009 Pearson Education, Inc.

خلية من النسيج الوسطي Leaf Cross Sectionقطاع عرضي في ورقة Leaf ورقة
Mesophyll ميزوفيل (النسيج الوسطي) Veinعرق Stomaالثغور CO2 O2 Mesophyll Cell خلية من النسيج الوسطي Figure 7.2 The location and structure of chloroplasts. The location and structure of chloroplasts مكان وتركيب البلاستيدات الخضراء Chloroplast بلاستيدات خضراء

الغشائيين الداخلي والخارجي
Chloroplast بلاستيدة خضراء Outer and inner membranes الغشائيين الداخلي والخارجي Intermembrane space الحيز بين الغشائي Thylakoid قريص Stroma حشوة Granum كيس قريصي Thylakoid Space حيز قريصي Figure 7.2 The location and structure of chloroplasts.

7.3 Plants produce O2 gas by splitting water تنتج النباتات غاز الأوكسجين بتجزئة الماء
Scientists have known for a long time that plants produce O2, but early on they assumed it was extracted from CO2 taken into the plant علم العلماء لفترة طويلة بأن النبات ينتج الأوكسجين ، ولكنهم كانوا يظنون بأنه يستخلص من ثاني أوكسيد الكربون الذي يدخل للنبات Using a heavy isotope of oxygen, 18O, they showed with tracer experiments that O2 actually comes from H2O باستخدام نظير مشع للأوكسجين (18O) أظهر العلماء بتجارب اقتفاء الأثر بأن الأوكسجين حقاً يأتي من الماء C. B. van Niel of Stanford University hypothesized that plants split water into hydrogen and oxygen. His hypothesis was confirmed 20 years later. A significant result of photosynthesis is the extraction of hydrogen from water and its incorporation into sugar. Oxygen is a waste product of photosynthesis. The chloroplast is the site where water is split into hydrogen and oxygen. Student Misconceptions and Concerns 1. Students may not connect the growth in plant mass to the fixation of carbon during the Calvin cycle. It can be difficult for many students to appreciate that molecules in air can contribute significantly to the mass of plants. Teaching Tips 1. Many students do not realize that glucose is not the direct product of photosynthesis. The authors note that although glucose is shown as a product of photosynthesis, a three-carbon sugar is directly produced (G3P). A plant can use G3P to make many types of organic molecules, including glucose. Oxygen bubbles on the leaves of an aquatic plant فقاعات الأوكسجين على أوراق نبات مائي Copyright © 2009 Pearson Education, Inc.

Experiment 1 Experiment 2 التجربة 2
التجربة 1 6 CO H2O C6H12O H2O O2 Not labeled غير معلم Experiment 2 التجربة 2 6 CO H2O C6H12O H2O O2 Figure 7.3B Experiments tracking the oxygen atoms in photosynthesis. Labeled معلم Experiments tracking the oxygen atoms in photosynthesis تجارب اقتفاء أثر ذرات الأوكسجين في البناء الضوئي

Fates of all the atoms in photosynthesis
مصير جميع الذرات في البناء الضوئي Reactants: متفاعلات 6 CO2 12 H2O Products: نواتج C6H12O6 6 H2O 6 O2 Figure 7.3C Fates of all the atoms in photosynthesis.

7.4 Photosynthesis is a redox process, as is cellular respiration البناء الضوئي هو عملية أخسدة كما هو الحال بالنسبة للتنفس الخلوي Photosynthesis, like respiration, is a redox (oxidation-reduction) process البناء الضوئي كالتنفس عبارة عن عملية أخسدة (أكسدة – إختزال) Water molecules are split apart by oxidation, which means that they lose electrons along with hydrogen ions (H+) تتجزأ جزيئات الماء بالأكسدة ، مما يعني أنها تخسر اليكترونات بالإضافة الى أيونات الهيدروجين جراء ذلك التجزؤ Then CO2 is reduced to sugar as electrons and hydrogen ions are added to it ثم يختزل ثاني أوكسيد الكربون إلى سكر بإضافة الإليكترونات وأيونات الهيدروجين اليه The simple sugar produced in photosynthesis is glucose, using a number of energy-releasing redox reactions. Teaching Tips 1. In our world, energy is frequently converted to a usable form in one place and used in another. For example, electricity is generated by power plants, transferred to our homes, and used to run computers, create light, and help us prepare foods. Consider relating this common energy transfer to the two-stage process of photosynthesis. Copyright © 2009 Pearson Education, Inc.

7.4 Photosynthesis is a redox process, as is cellular respiration البناء الضوئي هو عملية أخسدة كما هو الحال بالنسبة للتنفس الخلوي Recall that cellular respiration uses redox reactions to harvest the chemical energy stored in a glucose molecule تذكر بأن التنفس الخلوي يستخدم تفاعلات الاخسدة لحصد الطاقة الكيميائية المختزنة في جزيء الجلوكوز This is accomplished by oxidizing the sugar and reducing O2 to H2O يتم ذلك بأكسدة السكر واختزال الأوكسجين لماء The electrons lose potential as they travel down an energy hill, the electron transport system تفقد الإليكترونات جهدها برحلانها أسفل هرم الطاقة (نظام النقل الاليكتروني) In contrast, the food-producing redox reactions of photosynthesis reverse the flow and involve an uphill climb وعلى العكس فإن تفاعلات الأخسدة المنتجة الغذاء بعملية البناء الضوئي تعكس التيار الإليكتروني بترحيله لأعلى الهرم In respiration, mitochondria harness chemical energy to synthesize ATP. In photosynthesis, the energy boost is provided by light and occurs in chloroplasts. Eventually, ATP is synthesized. Teaching Tips 1. In our world, energy is frequently converted to a usable form in one place and used in another. For example, electricity is generated by power plants, transferred to our homes, and used to run computers, create light, and help us prepare foods. Consider relating this common energy transfer to the two-stage process of photosynthesis. Copyright © 2009 Pearson Education, Inc.

6 CO2 + 6 H2O C6H12O6 + 6 O2 Reduction الاختزال Oxidation الأكسدة
Photosynthesis (uses light energy) البناء الضوئي (يستخدم الطاقة الضوئية) 6 CO H2O C6H12O O2 Reduction الاختزال Oxidation الأكسدة Cellular respiration (releases chemical energy) التنفس الخلوي (تحرير الطاقة الكيميائية) Figure 7.4B Cellular respiration (releases chemical energy). 6 CO H2O C6H12O O2 Reduction إختزال Oxidation أكسدة

7.5 Overview: The two stages of photosynthesis are linked by ATP and NADPH نظرة شاملة : ترتبط مرحلتي البناء الضوئي بـ ATP و NADH Actually, photosynthesis occurs in two metabolic stages في الواقع يحدث البناء الضوئي على مرحلتين أيضيتين First stage One stage involves the light reactions تتضمن أحدى المراحل التفاعلات الضوئية In the light reactions, light energy is converted in the thylakoid membranes to chemical energy and O2 في تفاعلات الضوء تحول الطاقة الضوئية في أغشية القريص إلى طاقة كيميائية وأوكسجين Water is split to provide the O2 as well as electrons يتجزأ الماء لتوفير الأوكسجين والإليكترونات The two metabolic stages are the light reactions and the Calvin cycle. Student Misconceptions and Concerns 1. Students may understand the overall chemical relationships between photosynthesis and cellular respiration, but many struggle to understand the use of carbon dioxide in the Calvin cycle. Photosynthesis is much more than gas exchange. Teaching Tips 1. In our world, energy is frequently converted to a usable form in one place and used in another. For example, electricity is generated by power plants, transferred to our homes, and used to run computers, create light, and help us prepare foods. Consider relating this common energy transfer to the two-stage process of photosynthesis. 2. Figure 7.5 is an important visual organizer that notes the key structures and functions of the two stages of photosynthesis. This figure demonstrates where water and sunlight are used in the thylakoid membranes to generate oxygen, ATP, and NADPH. The second step, in the stroma, reveals the use of carbon dioxide, ATP, and NADPH to generate carbohydrates. Copyright © 2009 Pearson Education, Inc.

7.5 Overview: The two stages of photosynthesis are linked by ATP and NADPH نظرة شاملة : ترتبط مرحلتي البناء الضوئي بـ ATP و NADH H+ ions reduce NADP+ to NADPH, which is an electron carrier similar to NADH تختزل أيونات الهيدروجين NADP+ إلى NADPH ، حيث هو حامل اليكتروني مثل NADH NADPH is temporarily stored and then shuttled into the Calvin cycle where it is used to make sugar يخزن NADPH مؤقتاً ثم يرحل لدورة كالفين حيثما يقوم بتصنيع السكر Finally, the light reactions generate ATP وأخيراً تولد تفاعلات الضوء ATP Catabolic processes like cellular respiration generally use NAD+ as the initial hydrogen acceptor, while anabolic reactions, such as photosynthesis, use NADP+. Sugar is not produced in the light reactions; it is not produced until the Calvin cycle, the second stage of photosynthesis. Student Misconceptions and Concerns 1. Students may understand the overall chemical relationships between photosynthesis and cellular respiration, but many struggle to understand the use of carbon dioxide in the Calvin cycle. Photosynthesis is much more than gas exchange. Teaching Tips 1. In our world, energy is frequently converted to a usable form in one place and used in another. For example, electricity is generated by power plants, transferred to our homes, and used to run computers, create light, and help us prepare foods. Consider relating this common energy transfer to the two-stage process of photosynthesis. 2. Figure 7.5 is an important visual organizer that notes the key structures and functions of the two stages of photosynthesis. This figure demonstrates where water and sunlight are used in the thylakoid membranes to generate oxygen, ATP, and NADPH. The second step, in the stroma, reveals the use of carbon dioxide, ATP, and NADPH to generate carbohydrates. Copyright © 2009 Pearson Education, Inc.

7.5 Overview: The two stages of photosynthesis are linked by ATP and NADPH نظرة شاملة : ترتبط مرحلتي البناء الضوئي بـ ATP و NADH Second stage The second stage is the Calvin cycle, which occurs in the stroma of the chloroplast المرحلة الثانية هي دورة كالفين ، والتي تحدث في حشوة البلاستيدات الخضراء It is a cyclic series of reactions that builds sugar molecules from CO2 and the products of the light reactions عبارة عن سلسلة دائرية من التفاعلات التي تبني جزيئات السكر من ثاني أوكسيد الكربون ونواتج تفاعلات الضوء During the Calvin cycle, CO2 is incorporated into organic compounds, a process called carbon fixation يندمج ثاني أوكسيد الكربون خلال دورة كالفين بالمركبات العضوية في عملية تدعى بتثبيت الكربون The Calvin cycle was named for the Nobel laureate, Melvin Calvin, who traced the path of carbon in the cycle. Student Misconceptions and Concerns 1. Students may understand the overall chemical relationships between photosynthesis and cellular respiration, but many struggle to understand the use of carbon dioxide in the Calvin cycle. Photosynthesis is much more than gas exchange. Teaching Tips 1. In our world, energy is frequently converted to a usable form in one place and used in another. For example, electricity is generated by power plants, transferred to our homes, and used to run computers, create light, and help us prepare foods. Consider relating this common energy transfer to the two-stage process of photosynthesis. 2. Figure 7.5 is an important visual organizer that notes the key structures and functions of the two stages of photosynthesis. This figure demonstrates where water and sunlight are used in the thylakoid membranes to generate oxygen, ATP, and NADPH. The second step, in the stroma, reveals the use of carbon dioxide, ATP, and NADPH to generate carbohydrates. Copyright © 2009 Pearson Education, Inc.

يوفر ATP الناتج من تفاعلات الضوء الطاقة الكيميائية للازمة لدورة كالفين
7.5 Overview: The two stages of photosynthesis are linked by ATP and NADPH نظرة شاملة : ترتبط مرحلتي البناء الضوئي بـ ATP و NADH NADPH produced by the light reactions provides the electrons for reducing carbon in the Calvin cycle NADPH الناتج بواسطة تفاعلات الضوء يوفر الإليكترونات اللازمة لاختزال الكربون في دورة كالفين ATP from the light reactions provides chemical energy for the Calvin cycle يوفر ATP الناتج من تفاعلات الضوء الطاقة الكيميائية للازمة لدورة كالفين The Calvin cycle is often called the dark (or light-independent) reactions تسمى دورة كالفين غالباً بتفاعلات الظلام (التفاعلات غير المعتمدة على الضوء) The Calvin cycle occurs during daytime in most plants when the light reactions are powering the cycle’s sugar assembly line. For the BioFlix Animation Photosynthesis, go to Animation and Video Files. For the Discovery Video Trees, go to Animation and Video Files. Student Misconceptions and Concerns 1. Students may understand the overall chemical relationships between photosynthesis and cellular respiration, but many struggle to understand the use of carbon dioxide in the Calvin cycle. Photosynthesis is much more than gas exchange. Teaching Tips 1. In our world, energy is frequently converted to a usable form in one place and used in another. For example, electricity is generated by power plants, transferred to our homes, and used to run computers, create light, and help us prepare foods. Consider relating this common energy transfer to the two-stage process of photosynthesis. 2. Figure 7.5 is an important visual organizer that notes the key structures and functions of the two stages of photosynthesis. This figure demonstrates where water and sunlight are used in the thylakoid membranes to generate oxygen, ATP, and NADPH. The second step, in the stroma, reveals the use of carbon dioxide, ATP, and NADPH to generate carbohydrates. Copyright © 2009 Pearson Education, Inc.

ضوء An overview of the two stages of
H2O Chloroplastبلاستيدة خضراء Light ضوء NADP+ ADP  P LIGHT REACTIONS تفاعلات الضوء (in thylakoids) (في القريصات) Figure 7.5 An overview of the two stages of photosynthesis that take place in a chloroplast. Figure 7.5 is an important visual organizer that notes the key structures and functions of the two stages of photosynthesis. This figure reminds students where water and sunlight are used in the thylakoid membranes to generate oxygen, ATP, and NADPH. The second step, in the stroma, reveals the use of carbon dioxide, ATP, and NADPH to generate carbohydrates. An overview of the two stages of photosynthesis that take place in a chloroplast نظرة شاملة لمرحلتي البناء الضوئي التي تتم في البلاستيدة الخضراء

اليكترونات H2O Chloroplastبلاستيدة خضراء Light ضوء NADP+ ADP  P LIGHT
REACTIONS (in thylakoids) ATP Figure 7.5 An overview of the two stages of photosynthesis that take place in a chloroplast. Figure 7.5 is an important visual organizer that notes the key structures and functions of the two stages of photosynthesis. This figure reminds students where water and sunlight are used in the thylakoid membranes to generate oxygen, ATP, and NADPH. The second step, in the stroma, reveals the use of carbon dioxide, ATP, and NADPH to generate carbohydrates. Electrons اليكترونات NADPH An overview of the two stages of photosynthesis that take place in a chloroplast نظرة شاملة لمرحلتي البناء الضوئي التي تتم في البلاستيدة الخضراء O2

البناء الضوئي التي تتم في البلاستيدة الخضراء
H2O CO2 Chloroplastبلاستيدة خضراء Light ضوء NADP+ ADP  P LIGHT REACTIONS تفاعلات الضوء CALVIN CYCLE دورة كالفين (in thylakoids) (في القريصات) (in stroma) (في الحشوة) ATP Figure 7.5 An overview of the two stages of photosynthesis that take place in a chloroplast. Figure 7.5 is an important visual organizer that notes the key structures and functions of the two stages of photosynthesis. This figure reminds students where water and sunlight are used in the thylakoid membranes to generate oxygen, ATP, and NADPH. The second step, in the stroma, reveals the use of carbon dioxide, ATP, and NADPH to generate carbohydrates. Electrons اليكترونات NADPH An overview of the two stages of photosynthesis that take place in a chloroplast نظرة شاملة لمرحلتي البناء الضوئي التي تتم في البلاستيدة الخضراء Sugar سكر O2

PHOTOSYNTHESIS REVIEWED AND EXTENDED مراجعة وتقييم عملية البناء الضوئي

7.11 Review: Photosynthesis uses light energy, CO2, and H2O to make food molecules مراجعة : يستخدم البناء الضوئي الطاقة الضوئية وثاني أوكسيد الكربون والماء لصنع جزيئات الغذاء The chloroplast, which integrates the two stages of photosynthesis, makes sugar from CO2 تقوم البلاستيدة الخضراء التي يتم بينها التكامل بين مرحلتي البناء الضوئي بتصنيع السكر من ثاني أوكسيد الكربون All but a few microscopic organisms depend on the food-making machinery of photosynthesis كل الكائنات فيما عد القليل من الكائنات المجهرية تعتمد على آلية صُنع الغذاء بواسطة عملية البناء الضوئي Plants make more food than they actually need and stockpile it as starch in roots, tubers, and fruits تصنع النباتات غذاءً أكثر من حاجتها الفعلية وتختزنه كنشا في الجذور والدرنات والثمار Although photosynthesizers produce sugar for self-consumption, their sugar is a source for virtually all other organisms on Earth. Student Misconceptions and Concerns 1. Some students do not realize that plant cells also have mitochondria. Instead, they assume that the chloroplasts are sufficient for the plant cell’s needs. As noted in the text, nearly 50% of the carbohydrates produced by plant cells are used for cellular respiration (involving mitochondria). Teaching Tips 1. Challenge students to explain how the energy in beef is ultimately derived from the sun. 2. The authors note that G3P is also used to produce cellulose, the most abundant compound on Earth. Each year, plants produce about 100 billion tons of cellulose! Copyright © 2009 Pearson Education, Inc.

أغشية القريصات Summary of the chemical processes of photosynthesis
ملخص التفاعلات الكيميائية للبناء الضوئي H2O CO2 Chloroplastبلاستيدة خضراء Light ضوء NADP+ ADP + P Photosystem II IIالنظام الضوئي CALVIN CYCLE RuBP Electron transport chains سلسلة النقل الايكتروني (in stroma) دورة كالفين (في الحشوة) 3-PGA Thylakoid Membranes أغشية القريصات Photosystem I Iالنظام الضوئي ATP Stromaالحشوة Figure 7.11 A summary of the chemical processes of photosynthesis. NADPH G3P Cellular respiration التنفس الخلوي Celluloseسيليلوز Starchنشا O2 Sugars سكر Other organic compounds مركبات عضوية أخرى LIGHT REACTIONSتفاعلات الضوء CALVIN CYCLEدورة كالفين

7.12 EVOLUTION CONNECTION: Adaptations that save water in hot, dry climates evolved in C4 and CAM plants رابطة تطورية : التكيفات التي تحفظ الماء في المناخ الحار والجاف في نباتات الكربون الرباعي (C4) و نباتات الأيض الحمضي العشبي (CAM) In hot climates, plant stomata close to reduce water loss so oxygen builds up تغلق ثغور النباتات في المناخ الحار لتقلل من فقدان الماء ليتم تراكم الأوكسجين Rubisco adds oxygen instead of carbon dioxide to RuBP and produces a two-carbon compound, a process called photorespiration يقوم الروبيسكو بإضافة الأوكسجين بدلاً من ثاني أوكسيد الكربون لمركبRuBP وينتج مركب ثنائي الكربون بعملية تسمى بالتنفس الضوئي Unlike photosynthesis, photorespiration produces no sugar, and unlike respiration, it produces no ATP وعلى عكس البناء الضوئي, فإن التنفس الضوئي لا ينتج سكراً ، وعلى عكس التنفس فهو لا ينتج ATP Botanists believe photorespiration is an evolutionary relic, left from times when there was little oxygen in the atmosphere. Teaching Tips 1. If you can find examples of C3, C4, and CAM plants, consider bringing them to class. Referring to living plants helps students understand these abstract concepts. Nice photographs can serve as a fine substitute. 2. Relate the properties of C3 and C4 plants to the regions of the country where each is grown. Students might generally understand that crops have specific requirements, but may not specifically relate these physiological differences to their geographic sites of production or specific evolutionary histories. Copyright © 2009 Pearson Education, Inc.

7.12 EVOLUTION CONNECTION: Adaptations that save water in hot, dry climates evolved in C4 and CAM plants رابطة تطورية : التكيفات التي تحفظ الماء في المناخ الحار والجاف في نباتات الكربون الرباعي (C4) و نباتات الأيض الحمضي العشبي (CAM) Some plants have evolved a means of carbon fixation that saves water during photosynthesis نجد أن بعض النباتات مُهيئه بوسائل لتثبيت الكربون الذي من شأنه الحفاظ على الماء أثناء عملية البناء الضوئي One group can shut its stomata when the weather is hot and dry to conserve water but is able to make sugar by photosynthesis فهناك مجموعة من النباتات التي يتم فيها غلق ثغورها عندما يكون الطقس حاراً و وجافاً لحفظ الماء بالإضافة إلى قدرتها على تصنيع السكر بالبناء الضوئي These are called the C4 plants because they first fix carbon dioxide into a four-carbon compound تسمى هذه المجموعة بنباتات الكربون الرباعي لأنها تُثبت في البداية ثاني أكسيد الكربون في مركب رباعي الكربون Teaching Tips 1. If you can find examples of C3, C4, and CAM plants, consider bringing them to class. Referring to living plants helps students understand these abstract concepts. Nice photographs can serve as a fine substitute. 2. Relate the properties of C3 and C4 plants to the regions of the country where each is grown. Students might generally understand that crops have specific requirements, but may not specifically relate these physiological differences to their geographic sites of production or specific evolutionary histories. Copyright © 2009 Pearson Education, Inc.

يحرر ثاني أكسيد الكربون في النهار أثناء ليدخل في دورة كالفين
7.12 EVOLUTION CONNECTION: Adaptations that save water in hot, dry climates evolved in C4 and CAM plants رابطة تطورية : التكيفات التي تحفظ الماء في المناخ الحار والجاف في نباتات الكربون الرباعي (C4) و نباتات الأيض الحمضي العشبي (CAM) Another adaptation to hot and dry environments has evolved in the CAM plants, such as pineapples and cacti في حين نجد أن مجموعة أخرى مهيئة بطريقة أخرى للتكيف مع البيئات الحارة والجافة وتنسمي نباتات الأيض الحمضي العشبي مثل الأناناس والصباريات CAM plants conserve water by opening their stomata and admitting CO2 only at night تختزن نباتات الأيض الحمضي الماء بفتح ثغورها في الليل فقط لدخول ثاني أكسيد الكربون When CO2 enters, it is fixed into a four-carbon compound, like in C4 plants, and in this way CO2 is banked عندما يدخل ثاني أكسيد الكربون, يُثبت على هيئة مركب رباعي الكربون كما في نباتات الكربون الرباعي ، وبذلك يُختزن ثاني أكسيد الكربون It is released into the Calvin cycle during the day يحرر ثاني أكسيد الكربون في النهار أثناء ليدخل في دورة كالفين For the BLAST Animation Photosynthesis: Light-Independent Reactions, go to Animation and Video Files. Teaching Tips 1. If you can find examples of C3, C4, and CAM plants, consider bringing them to class. Referring to living plants helps students understand these abstract concepts. Nice photographs can serve as a fine substitute. 2. Relate the properties of C3 and C4 plants to the regions of the country where each is grown. Students might generally understand that crops have specific requirements, but may not specifically relate these physiological differences to their geographic sites of production or specific evolutionary histories. Copyright © 2009 Pearson Education, Inc.

Comparison of photosynthesis in C4 and CAM plants
Mesophyll cell CO2 CO2 Night الليل خلية الطبقة المتوسطة 4-C compound مركب رباعي الكربون 4-C compound مركب رباعي الكربون CO2 CO2 CALVIN CYCLE دورة كالفين CALVIN CYCLE دورة كالفين Figure 7.12 Comparison of photosynthesis in C4 and CAM plants: In both pathways, CO2 is first incorporated into a four-carbon compound, which then provides CO2 to the Calvin cycle. خلية حزمية Bundle- sheath cell 3-C sugar سكر ثلاثي الكربون 3-C sugarسكر ثلاثي الكربون Day النهار C4 plant نبات رباعي الكربون CAM plant نبات أيض حمضي Comparison of photosynthesis in C4 and CAM plants مقارنة بين البناء الضوئي في نباتات رباعي الكربون ونباتات الأيض الحمضي

7.13 CONNECTION: Photosynthesis moderates global warming رابطة تطبيقية : يقلل البناء الضوئي من حدة الاحتباس الحراري The greenhouse effect results from solar energy warming our planet ينتج تأثير الدفيئة من تدفئة الطاقة الشمسية لكوكبنا Gases in the atmosphere (often called greenhouse gases), including CO2, reflect heat back to Earth, keeping the planet warm and supporting life الغازات الموجودة في الغلاف الجوي (تسمى غالباً بغازات الدفيئة) بما فيها ثاني أكسيد الكربون تعكس الحرارة إلى كوكب الأرض مرة أخرى ، مما يجعل الكوكب دافئاً بالقدر الذي يدعم الحياة على الكرة الأرضية However, as we increase the level of greenhouse gases, Earth’s temperature rises above normal, initiating problems إلا أنه, بزيادتنا لمستوى غازات الدفيئة، ترتفع درجة حرارة كوكب الأرض لتتجاوز الحد الطبيعي، مما يؤدي إلى بداية ظهور المشاكل Student Misconceptions and Concerns 1. Students may confuse global warming with the breakdown of the ozone layer. Be prepared to explain both phenomena and the impact of human activities. 2. Students often do not fully understand how the burning of fossil fuels contributes to global warming. They might wonder, “How does the burning of fossil fuels differ from the burning of ethanol produced from crops?” Students might not realize that the carbon in fossil fuels was removed from the atmosphere hundreds of millions of years ago, while the carbon in crops was removed much more recently, when the crops were grown. Teaching Tips 1. Some students might better relate the greenhouse effect to what happens inside their closed car on a sunny day. The glass in our automobiles functions just like the glass of a greenhouse, trapping heat inside our car. This can be an advantage during the winter but is usually not welcome on a hot summer day! Copyright © 2009 Pearson Education, Inc.

تؤدي زيادة تركيزات غازات الدفيئة إلى الاحتباس الحراري
7.13 CONNECTION: Photosynthesis moderates global warming رابطة تطبيقية : يقلل البناء الضوئي من حدة الاحتباس الحراري Increasing concentrations of greenhouse gases lead to global warming, a slow but steady rise in Earth’s surface temperature تؤدي زيادة تركيزات غازات الدفيئة إلى الاحتباس الحراري The extraordinary rise in CO2 is mostly due to the combustion of carbon-based fossil fuels الارتفاع فوق الطبيعي لمعدل ثاني أكسيد الكربون يكون غالباً بسبب احتراق الوقود الكربوني الاحفوري The consequences of continued rise will be melting of polar ice, changing weather patterns, and spread of tropical disease تؤدي تداعيات الارتفاع المستمر في معدلات ثاني أكسيد الكربون إلى ذوبان الثلج القطبي, فتتغير أنماط الطقس وتنتشر الأمراض الاستوائية Student Misconceptions and Concerns 1. Students may confuse global warming with the breakdown of the ozone layer. Be prepared to explain both phenomena and the impact of human activities. 2. Students often do not fully understand how the burning of fossil fuels contributes to global warming. They might wonder, “How does the burning of fossil fuels differ from the burning of ethanol produced from crops?” Students might not realize that the carbon in fossil fuels was removed from the atmosphere hundreds of millions of years ago, while the carbon in crops was removed much more recently, when the crops were grown. Teaching Tips 1. Some students might better relate the greenhouse effect to what happens inside their closed car on a sunny day. The glass in our automobiles functions just like the glass of a greenhouse, trapping heat inside our car. This can be an advantage during the winter but is usually not welcome on a hot summer day! Copyright © 2009 Pearson Education, Inc.

Perhaps photosynthesis can mitigate the increase in atmospheric CO2
7.13 CONNECTION: Photosynthesis moderates global warming رابطة تطبيقية : يقلل البناء الضوئي من حدة الاحتباس الحراري Perhaps photosynthesis can mitigate the increase in atmospheric CO2 ربما يستطيع البناء الضوئي التخفيف من حدة زيادة ثاني أكسيد الكربون في الغلاف الجوي However, there is increasing widespread deforestation, which aggravates the global warming problem إلا أن هناك تزايد في عملية القطع الجائر للغابات ، مما يفاقم ويزيد من مشكلة الاحتباس الحراري Student Misconceptions and Concerns 1. Students may confuse global warming with the breakdown of the ozone layer. Be prepared to explain both phenomena and the impact of human activities. 2. Students often do not fully understand how the burning of fossil fuels contributes to global warming. They might wonder, “How does the burning of fossil fuels differ from the burning of ethanol produced from crops?” Students might not realize that the carbon in fossil fuels was removed from the atmosphere hundreds of millions of years ago, while the carbon in crops was removed much more recently, when the crops were grown. Teaching Tips 1. Some students might better relate the greenhouse effect to what happens inside their closed car on a sunny day. The glass in our automobiles functions just like the glass of a greenhouse, trapping heat inside our car. This can be an advantage during the winter but is usually not welcome on a hot summer day! Copyright © 2009 Pearson Education, Inc.

Plants growing in a greenhouse نباتات تنمو في دفيئة ”صَوبة“
Figure 7.13A Plants growing in a greenhouse. Plants growing in a greenhouse نباتات تنمو في دفيئة ”صَوبة“

تتسرب بعض الطاقة الحرارية للفضاء Sunlight أشعة الشمس
Some heat energy escapes into space تتسرب بعض الطاقة الحرارية للفضاء Sunlight أشعة الشمس Atmosphere الغلاف الجوي Radiant heat trapped by CO2 and other gases الحرارة الإشعاعية المحتجزة بواسطة ثاني أكسيد الكربون والغازات الأخرى Figure 7.13B CO2 in the atmosphere and global warming. CO2 in the atmosphere and global warming ثاني أكسيد الكربون في الغلاف الجوي والانحباس الحراري

7.14 TALKING ABOUT SCIENCE: Mario Molina talks about Earth’s protective ozone layer حديث العلم : يتحدث ماريو مولينا عن طبقة الأوزون الحامية للأرض Mario Molina at the University of California, San Diego, received a Nobel Prize for research on damage to the ozone layer ماريو مولينا من جامعة كاليفورنيا – سان دييجو ، فاز بجائزة نوبل للبحث في ثقب طبقة الأوزون Ozone provides a protective layer (the ozone layer) in our atmosphere to filter out powerful ultraviolet radiation يوفر الأوزون طبقة حامية (طبقة الأوزون) لغلافنا الجوي حيث يقوم بترشيح الأشعة فوق البنفسجية القوية فيمنع وصولها للأرض Dr. Molina showed that industrial chemicals called chlorofluorocarbons, or CFCs, deplete the ozone layer أثبت د. مولينا بن المواد الكيميائية الصناعية والتي تسمى بالكربونات الفلورية الكلورية (CFCs) تستهلك طبقة الأوزون Student Misconceptions and Concerns 1. Students may confuse global warming with the breakdown of the ozone layer. Be prepared to explain both phenomena and the impact of human activities. Teaching Tips 1. Consider an analogy between the ozone layer and sunscreen applied to the skin. The thinning of the ozone layer is like putting on less and less sunscreen. In both situations, more harmful UV light penetrates the layers and causes damage. 2. Frustration can overwhelm concerned students alarmed by the many problems addressed in this chapter. One way to address this is to provide meaningful ways for students to respond to this information (for example, changes in personal choices and voting). The Earth Day Network, is just one of many Internet sites devoted to positive action. Copyright © 2009 Pearson Education, Inc. 117

Mario Molinaماريو مولينا
Figure 7.14A Mario Molina. Mario Molinaماريو مولينا 118

المحيط المتجمد الجنوبي
Southern tip of South America القمة الجنوبية لأمريكا الجنوبية Antarctica المحيط المتجمد الجنوبي Figure 7.14B The ozone hole in the Southern Hemisphere, spring 2006. The ozone hole in the Southern Hemisphere, spring 2006 ثقب الأوزون في نصف الكرة الأرضية الجنوبي ، ربيع 2006م 119

MEMBRANE STRUCTURE AND FUNCTION

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