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1.Biosphere Land – water – atmosphere (inhabited by life). 2. Ecosystem Living thing and non-living thing with which life interacts in particular area.

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Presentation on theme: "1.Biosphere Land – water – atmosphere (inhabited by life). 2. Ecosystem Living thing and non-living thing with which life interacts in particular area."— Presentation transcript:

1 1.Biosphere Land – water – atmosphere (inhabited by life). 2. Ecosystem Living thing and non-living thing with which life interacts in particular area (forests or oceans or deserts). 3.Community living different species in particular ecosystem. 4.Population one species. 5.Organism one individual (Body). 6.Organs 7.Tissues 8.Cells 9.Organelles 10.Molecules Biology

2 1.Organic compounds (macromolecules) Carbohydrates, lipid, proteins, vitamins and nucleic acid 1.Inorganic compounds (micromolecules) Water and minerals Molecules

3 THE STRUCTURE AND FUNCTION OF MACROMOLECULES Polymer principles And Macromolecules Polymer principles And Macromolecules

4 Cells link smaller organic molecules together to form larger molecules. macromoleculesThese larger molecules called macromolecules. carbohydrates, lipids, proteins, and nucleic acids.The four major classes of macromolecules are: carbohydrates, lipids, proteins, and nucleic acids. polymersMost macromolecules are polymers monomerscovalent bonds –Polymers consist of many similar or identical building blocks, called monomers. Linked by covalent bonds. Introduction ( Polymers principles )

5 Covalent bondsCovalent bonds are formed by a dehydration reaction تفاعل نزع الماء. hydroxyl group hydrogen –One monomer provides a hydroxyl group and the other provides a hydrogen to form water. –This process requires energy and is aided by enzymes. وبالعكسVise versa hydrolysis (hydration)The covalent bonds connecting monomers in a polymer are disassembled تـُكسَــر by hydrolysis (hydration) بإضافة الماء. –In hydrolysis as the covalent bond is broken a hydrogen atom and hydroxyl group from a split water molecule attaches where the covalent bond used to be. –Hydrolysis reactions dominate the digestive process, guided by specific enzymes.

6 (Carbohydrates, Lipids, Proteins and nucleic acids) Mono-merDi-merPoly-mer Polymer Polymer is a long molecule consists of a chain of similar building molecules (monomers) covalently bounded together. Polymer can be broken down يـُكَســًر إلى to its monomers by hydrolysis (adding H 2 O). Polymer can be built up يـُبـْنَى by linking its monomers by dehydration (removing H 2 O). أحادى ثنائى عديد

7 THE STRUCTURE AND FUNCTION OF MACROMOLECULES 1- Carbohydrates Fuel and Building Material (مادة الطاقة و البناء ) 1.Sugars, the smallest carbohydrates, serve as fuel and carbon sources 2.Polysaccharides, the polymers of sugars, have storage and structural roles

8 Carbohydrates include sugars. Monosaccharides,Monosaccharides, are the simplest carbohydrates (simple sugars). DisaccharidesDisaccharides, double sugars, consist of two monosaccharides joined by dehydration. Polysaccharides,Polysaccharides, are polymers of many monosaccharides. ___________________ carbonyl grouphydroxyl groups.Monosaccharides have a carbonyl group (C=O) and multiple hydroxyl groups (O-H). carbonly groupCaldose ()ketose () –If the carbonly group is at the end of C chain, the sugar is called aldose (aldehyde sugar), if not, the sugars is called ketose (Ketone sugar). –Glucosefructose –Glucose called “aldose”, and fructose called “ketose”. They are structural isomers.

9 Aldose Ketose 1- Monosaccharides C C C C C C OH OHH OHH OHH OHH OHH H Glucose C 6 H 12 O 6 C C C C C C OHH OH OH OH OHH H H H O HH Fructose

10 C C C C C C OHH OH OH OH OHH H H H O HH C C COHOHH OHH H C C C C COHOH OH OHH H H OHH H Triose SugarPentose SugarHexose Sugar C C C COHOH OHH H OHH H Tetrose Sugar Types of monosaccharides, based on the number of C atoms

11 Monosaccharides are also classified by the number of carbons in the backbone.Monosaccharides are also classified by the number of carbons in the backbone. –Glucose and other six carbon sugars are hexoses. –Glucose and other six carbon sugars are hexoses سداسى. –Five carbon backbones are pentoses and three carbon sugars are trioses. –Five carbon backbones are pentoses خماسى and three carbon sugars are trioses ثلاثى. Aldehyde sugars Ketone sugars

12 Summary Monosaccharides are classified into :- C Aldoses: are the monosaccharides of carbonyle group ( C=O) at the end of C chain (e.g. Glucose). C Ketoses: are the monosaccharides of C=O carbonyle group within داخل the C chain (e.g. Fructose). 3C Triose (3C): e.g. Glyceraldehyde. A- Based on the location of C=O B- Based on the number of C in the skeleton 5C Pentose (5C): e.g. Ribose. Hexose6C Hexose (6C): e.g. Glucose, Fructose and Galactose.

13 2- Disaccharides السكر الثنائى Consist of 2 monosaccharide molecules during a dehydration reaction تفاعل نزع الماء. 2(C 6 H 12 O 6 ) C 12 H 22 O 11 + H 2 O 2 GlucoseMaltose 1- Maltose (malt sugar)

14 2- Lactose (milk sugar): consists of Glucose + Galactose. 3- Sucrose (table sugar): consists of Glucose + Fructose.

15 3- Polysaccharides السكر العديد Consist of few hundreds to few thousands of monosaccharides. They are two types: 1- Storage تخزينية. Provide sugar for cell, when needs, by hydrolysis 1- Storage تخزينية. Provide sugar for cell, when needs, by hydrolysis 2- Structural. Serve as building materials for the organism 2- Structural تركيبية. Serve as building materials for the organism

16 I- Starch النشا A storage polysaccharide of plants (). A storage polysaccharide of plants (within plastids). It is consisted of thousands of α glucose molecules. Thus, it gives glucose when hydrolysed by special enzymes Thus, it gives glucose when hydrolysed بإضافة الماء by special enzymes in human. Potatos and grains are the major source of starch. A)- Storage Polysaccharides

17 II- Glycogen Stored in animal cells (). Stored in animal cells (e.g. liver and muscle cells in Human). It is consisted of thousands of glucose molecules. Thus, it gives glucose when hydrolysed.

18 B)- Structural Polysaccharides I- Cellulose Forms the micro-fibrils and cell wall in plants. It is consisted of thousands of β glucose molecules. Human cannot digest it, but some bacteria and protozoa can ( ). Human cannot digest it, but some bacteria and protozoa can (e.g. in Termites and Cows stomach). It is the building material of plants (cell wall).

19 Arrangement of cellulose in plants

20 The enzymes that digest starch cannot hydrolyze the beta linkages in cellulose. –Cellulose in our food passes through the digestive tract and is eliminated in feces as “insoluble fiber”. –As it travels through the digestive tract, it abrades يثير the intestinal walls and stimulates the secretion of mucus.

21 cellulaseSome microbes can digest cellulose to its glucose monomers through the use of cellulase enzymes. Many eukaryotic herbivores آكلات العشب, like cows and termites, have symbiotic relationships with cellulolytic microbes, allowing them access to this rich source of energy.

22 II- Chitin الكيتين N It is consisted of thousands of glucose molecules with a N atom in one end. It is used to manufacture the surgical threads. It is the building material of the cuticle الجُـلَيد in insects.

23 Carbohydrates Location of Carbonyl Group Aldose C=O group is TerminalKetose C=O group in middle MonosaccharidesDisaccharides Polysaccharides Glucose, galactose & Fructose Maltose, Lactose & Sucrose StorageStructural Starch (inplants) & Glycogen (inanimals) Starch (in plants) & Glycogen (in animals) Cellulose (in plants) & Chitin (in insects) & Chitin (in insects) No. of C atoms No. of C atoms No. of sugar molecules Triose (3C) Glyceraldehyde Pentose (5C) Ribose Hexose (6C) Glucose

24 THE STRUCTURE AND FUNCTION OF MACROMOLECULES 3) Proteins :- Many Structures, Many Functions 1.A polypeptide is a polymer of amino acids connected in a specific sequence 2.A protein’s function depends on its specific conformation

25  Their functions include structural support, storage, transport of other substances, intercellular signaling الإشارات بين الخلوية, movement, defense against microbes and work as enzymes in the cell that regulate metabolism الأيض.  Humans have tens of thousands of different proteins, each with their own structure and function.  All protein polymers are constructed from تتركب من the same set of 20 monomers, called amino acids.  Polymers of proteins are called polypeptides ببتيدات عديدة.  A protein consists of one or more polypeptides folded and coiled into a specific conformation 3) Proteins

26 - The physical and chemical characteristics صفات of the R group determine تحدد the unique characteristics of a particular amino acid. Side chain Amino group Carboxyl group General Formula of the Amino Acid: CHR N H H C OHOHOHOH O R - The side chain R links with ترتبط بـ different compounds - Monomer of amino acid includes a hydrogen atom, a carboxyl group, an amino group, and a variable متغيرة R group (or side chain), all covalently bonded to C atom. - Differences in R groups produce the 20 different amino acids.

27 1.Hydrophobic: the amino acids that have hydrophobic R groups (non-polar). Amino acids الأحماض الأمينية

28 2- Hydrophilic: the amino acids that have polar R groups, making them hydrophilic. 3- Ionized: the amino acids with functional groups that are charged (ionized) at cellular pH (7). So, some R groups are bases, others are acids. 3- Ionized: the amino acids with functional groups that are charged (ionized) at cellular pH (7). So, some R groups are bases, others are acids.

29 The Peptide Bond الرابطة البيبتيدية Peptide bond formed between the carboxyl group of one amino acid and the amino group of the other by dehydration. OHOHOHOH C C H R N H H O H CHR NHC OHOHOHOH O Peptide bond Polypeptide (Protein) Dehydration نزع الماء Amino acids Peptide

30 Amino acids are joined together when a dehydration reaction removes a hydroxyl group from the carboxyl end of one amino acid and a hydrogen from the amino group of another. The resulting covalent bond is called a peptide bond.Amino acids are joined together when a dehydration reaction removes a hydroxyl group from the carboxyl end of one amino acid and a hydrogen from the amino group of another. The resulting covalent bond is called a peptide bond. Repeating the process over and over عدة مرات creates a long polypeptide chain.Repeating the process over and over عدة مرات creates a long polypeptide chain. –At one end is an amino acid with a free amino group the (the N-terminus) and at the other is an amino acid with a free carboxyl group the (the C- terminus). The repeated sequence (N-C-C) is the polypeptide backbone.The repeated sequence (N-C-C) is the polypeptide backbone. Attached to the backbone are the various R groups.Attached to the backbone are the various R groups. Polypeptides range in size from a few monomers to thousands.Polypeptides range in size from a few monomers to thousands.

31 The folding إلتفاف of a protein from a chain of amino acids occurs spontaneously ذاتيا.The folding إلتفاف of a protein from a chain of amino acids occurs spontaneously ذاتيا. There are three levels of structure: primary أولى, secondary ثانوى, and tertiary ثلاثى structure, are used to organize the folding within a single peptide chain.There are three levels of structure: primary أولى, secondary ثانوى, and tertiary ثلاثى structure, are used to organize the folding within a single peptide chain. Quaternary رُباعى structure arises when two or more polypeptides (proteins) join to form another kind of protein.Quaternary رُباعى structure arises when two or more polypeptides (proteins) join to form another kind of protein. Levels of Protein Structure

32 1.Primary structure: It is a single peptide chain of amino acids. –Lysozyme, an enzyme that attacks bacteria, consists of a polypeptide chain of 129 amino acids. –A slight change تغيير طفيف in the primary structure can affect a protein’s conformation and ability to function.

33 Sickle cell disease المنجلية خلايا الدم :Sickle cell disease المنجلية خلايا الدم : an abnormal hemoglobin because of a single amino acid substitution تغيير. an abnormal hemoglobin because of a single amino acid substitution تغيير. –These abnormal hemoglobin crystallize, deforming يُكسر the red blood cells and leading to clogs إنسداد in tiny blood vessels أوعية.

34 2. The secondary structure: على أبعاد متساوية Results from hydrogen bonds at regular intervals على أبعاد متساوية along the polypeptide backbone. A. Coils الحلزونى A. Coils الحلزونى (α- helix ) are typical shapes that develop from secondary structure B.Folds B.Folds ( β-pleated sheets ) الشيت المُجعـد الشيت المُجعـد. Composed of several parallel α-helix coils attached by H bonds

35 An example for folds (β-pleated sheets) الشيت المُجعد: الحرير Is the structural properties of silk الحرير because of the presence of so many hydrogen bonds makes each silk fiber stronger than steel.

36 3. Tertiary structure: among خلال R groups between R groups and the polypeptide backbone is determined by a variety of interactions among خلال R groups and between R groups and the polypeptide backbone. hydrogen bonds ionic bonds Van der Waals interactions –These interactions include weak bonds like hydrogen bonds among polar areas, ionic bonds between charged R groups, and hydrophobic interactions and Van der Waals interactions among hydrophobic R groups. disulfidebridges - Also include disulfide bridges, strong covalent bonds that form between the sulfhydryl groups (SH) of cysteine monomers, stabilize the structure.

37 4- The quaternary structure: Results from the aggregation تجمع of two or more polypeptide chains. Collagen Collagen is a fibrous protein of three polypeptides that are supercoiled, and function in connective tissues.Hemoglobin is a globular protein with two copies of two kinds of polypeptides (2α and 2β). Collagen Hemoglobin

38 The 4 forms of protein

39 It is the change of protein’s conformation in response to إستجابة لـ the physical and chemical conditions.It is the change of protein’s conformation in response to إستجابة لـ the physical and chemical conditions. For example, alterations تغيير in pH, salt concentration, temperature, or other factors can denature يفرد a protein.For example, alterations تغيير in pH, salt concentration, temperature, or other factors can denature يفرد a protein. –These forces break the hydrogen bonds, ionic bonds, and disulfide bridges that maintain the protein’s complicated shape. Some proteins can return to their original shape again after denaturation, but others cannot.Some proteins can return to their original shape again after denaturation, but others cannot. Denaturation of protein فرْد البروتين

40 مفرود Denaturation of protein فرد البروتين فرد إعادة إلى طبيعته

41 Amino acids Primary structure Secondary structure Tertiary structure Quaternary structure 1- Hydrophobic Interaction (Van der Waals interaction); 2- H bonds; 3- Ionic bonds; 4- Di-sulfide bridges; Single chain of amino acids e.g. Lysozyme Coils & Folds H bonds e.g. silk e.g. Collagen & Hemoglobin two or more polypeptidechains PeptidesPeptides Peptide ponds Dehydration Hydrophobic () Hydrophobic (non-polar R group) Hydrophilic () Hydrophilic (polar R group) Ionized (charged functional groups Ionized (charged functional groups) ProteinsProteins Polypeptides

42 Lipids; The Hydrophobic Molecules 1.Fats store large amounts of energy 2.Phospholipids are major components of cell membranes 3.Steroids include cholesterol and certain hormones 1.Fats store large amounts of energy 2.Phospholipids are major components of cell membranes 3.Steroids include cholesterol and certain hormones

43 Lipids are an exception among macromolecules because they do not have polymers.Lipids are an exception among macromolecules because they do not have polymers. The unifying feature الصفة المُمَيـٍزة of lipids is that they all have little or no affinity for water لا تـَمتزج بالماء.The unifying feature الصفة المُمَيـٍزة of lipids is that they all have little or no affinity for water لا تـَمتزج بالماء. –This is because their structures are dominated by non-polar covalent bonds. Lipids are the components مُكونات of fats, and are highly diverse in form and function.Lipids are the components مُكونات of fats, and are highly diverse in form and function. Although fats are not polymers, they are large molecules assembled from تتكون من smaller molecules by dehydration reactions.Although fats are not polymers, they are large molecules assembled from تتكون من smaller molecules by dehydration reactions. A fat is constructed from two kinds of smaller molecules, glycerol and fatty acids.A fat is constructed from two kinds of smaller molecules, glycerol and fatty acids أحماض دُهنية. 1) Fats:

44 A fat is composed of three fatty acids linked with one glycerol molecule. Fats are classified into Saturated مشبع and Un-saturated غير مشبع fats OHOH H H C C C C C C H H H H H H H H H O O C C C H H H H OHOH OHOH H H Dehydration Fatty Acid Glycerol Glycerol consists of a three C skeleton with an OH group attached to each C. A fatty acid consists of a carboxyl group ( COOH ) attached to a long carbon skeleton, often 16 to 18 carbons long. Ester link

45 The many non-polar C-H bonds in the long hydrocarbon skeleton make fats hydrophobic.The many non-polar C-H bonds in the long hydrocarbon skeleton make fats hydrophobic. In a fat, three fatty acids are joined to glycerol by an ester linkage, رابطة إستيرية creating a triacylglycerol.In a fat, three fatty acids are joined to glycerol by an ester linkage, رابطة إستيرية creating a triacylglycerol.

46 Fatty acids may vary تختلف in length (number of carbons) and in the number and locations of double bonds. carbon-carbon double bonds مشبع H –If there are no carbon-carbon double bonds, then the molecule is a saturated fatty acid مشبع (has H at every possible position). one or more carbon-carbon double bonds حامض دهنىغير مشبع HIf there are one or more carbon-carbon double bonds, then the molecule is an unsaturated fatty acid حامض دهنى غير مشبع - formed by the removal of H atoms from the carbon skeleton.

47 A)- Saturated Fats الدهون المشبعة The Fatty acid components are saturated (there is no double bonds between the carbons. All C are linked with H. Thus, it is saturated with H. Most animal fats are saturated. They are solid at room temperature. Saturated fats-rich diet results in Atherosclerosis التصلب الشريانى. These double bonds are formed by the removal of H atoms. Most vegetable fats (oils) and fish fats are unsaturated. They are liquid at room temperature. They can be synthetically converted to saturated (solid) by adding H (Hydrogenation الهَدْرَﭽـَة). B)- Un-saturated Fats الغيرمشبعةالدهون B)- Un-saturated Fats الغير مشبعة الدهون

48 The major function of fats is energy storage.The major function of fats is energy storage. –A gram of fat stores more than twice as much energy as a gram of a polysaccharide. –Humans and other mammals store fats as long-term energy reserves كمخزون طاقة طويل المدى in adipose cells خلايا دهنية.

49 Phospholipids have two fatty acids attached to glycerol and a phosphate group at the third position.Phospholipids have two fatty acids attached to glycerol and a phosphate group at the third position. –The phosphate group carries a negative charge –The phosphate group carries a negative charge. 2) Phospholipids; Are major components of cell membranes The interaction of phospholipids with water is complex.The interaction of phospholipids with water is complex. The fatty acid tails are hydrophobic, but the phosphate group and its attachments form a hydrophilic head.The fatty acid tails are hydrophobic, but the phosphate group and its attachments form a hydrophilic head.

50 When phospholipids are added to water, they self-assemble تتشكل ذاتيا into aggregates تجمعات with the hydrophobic tails pointing toward the center and the hydrophilic heads on the outside.When phospholipids are added to water, they self-assemble تتشكل ذاتيا into aggregates تجمعات with the hydrophobic tails pointing toward the center and the hydrophilic heads on the outside. –This type of structure is called a micelle الزهرة. At the surface of a cell phospholipids are arranged as a bilayer طبقة مزدوجة.At the surface of a cell phospholipids are arranged as a bilayer طبقة مزدوجة. –Again, the hydrophilic heads are on the outside in contact with the aqueous solution المحلول المائى and the hydrophobic tails in the core المركز. –The phospholipid bilayer طبقة مزدوجة forms a barrier حاجز between the cell and the external environment البيئة الخارجية. They are the major component of cell membranes.They are the major component of cell membranes.

51 Steroids are lipids with a carbon skeleton consisting of four fused ملتحمة carbon rings.Steroids are lipids with a carbon skeleton consisting of four fused ملتحمة carbon rings. –Different steroids are created by varying functional groups attached to the rings. 3) Steroids: Include cholesterol and certain hormones Cholesterol, an important steroid, is a component in animal cell membranes.Cholesterol, an important steroid, is a component in animal cell membranes. Cholesterol is also the precursor المادة الخام from which all other steroids are synthesized. Cholesterol is also the precursor المادة الخام from which all other steroids are synthesized. Many of these other steroids are hormones, including the sex Many of these other steroids are hormones, including the sex hormones. hormones. While cholesterol is clearly an essential molecule, high levels of cholesterol in the blood may contribute to Atherosclerosis تصلب الشرايين While cholesterol is clearly an essential molecule, high levels of cholesterol in the blood may contribute to Atherosclerosis تصلب الشرايين

52 F a t s (Composed of Lipids) SaturatedSaturatedUnsaturatedUnsaturatedPhospholipidsPhospholipids Animal FatsVegetable Fats Bi-layer of cell membrane Hydrogenationهَـدْرَﭽـَــــــــة SteroidsSteroids Sex Hormones & Cholesterol

53 CHAPTER 5 THE STRUCTURE AND FUNCTION OF MACROMOLECULES THE STRUCTURE AND FUNCTION OF MACROMOLECULES 4- Nucleic Acids: The Informational Polymers 1.Nucleic acids store and transmit hereditary information المعلومات الوراثية 2.A nucleic acid strand is a polymer of nucleotides 3.Inheritance is based on replication of the DNA double helix

54 DNA is located in the nucleus There are two types of nucleic acidsThere are two types of nucleic acids ribonucleic acid (RNA) ribonucleic acid (RNA)And deoxyribonucleic acid (DNA). DNA Structure

55 Structures of nucleic acids (DNA & RNA) o H H H H H CH 2 o P o o o Sugar-phosphate backbone Base o P o o o o H H H H H CH 2 Base DNA nucleotide Bases Thymine (T) Adenine (A) Cytosine (C) Guanine (G) Purine Pyrimidine Deoxyribose sugar Phosphate group 1 2 3 4 5 353 5 3

56 The PO 4 group of one nucleotide is attached to the sugar of the next nucleotide in line فى صف مستقيم.The PO 4 group of one nucleotide is attached to the sugar of the next nucleotide in line فى صف مستقيم. The result is a “backbone” of alternating تبادل phosphates and sugars, from which the bases starts.The result is a “backbone” of alternating تبادل phosphates and sugars, from which the bases starts.

57 Nitrogenous bases القواعد النيتروجينية Sugar-phosphate backbones Thymine (T) Adenine (A) Cytosine (C) Guanine (G) Purine Pyrimidines Hydrogen bonds Nitrogenous bases 5 3 5 3 Uracil (U)

58 Adenine (A) would form 2 hydrogen bonds only with thymine (T) Adenine (A) would form 2 hydrogen bonds only with thymine (T) Guanine (G) would form 3 hydrogen bonds only with cytosine (C). Guanine (G) would form 3 hydrogen bonds only with cytosine (C). DNA

59 DNA & RNA o H H H H H CH 2 Deoxyribose sugar ( O on C2 is missed ) o OH H H H H CH 2 Ribose sugar (no missed O) R ibo- N ucleic- A cid D eoxiribo- N ucleic- A cid Single stranded nucleic acid Double stranded nucleic acid Bases: A, G, C, T Bases: A, G, C, U

60

61 Nucleic acids are polymers of monomers called nucleotides.Nucleic acids are polymers of monomers called nucleotides. Each nucleotide consists of three parts: a nitrogen base, a pentose sugar, and a phosphate group.Each nucleotide consists of three parts: a nitrogen base, a pentose sugar, and a phosphate group. The nitrogen bases (rings of carbon and nitrogen) come in two types: Purines and Pyrimidines.The nitrogen bases (rings of carbon and nitrogen) come in two types: Purines and Pyrimidines. The pentose sugar joined to the nitrogen base is ribose in nucleotides of RNA and deoxyribose in DNA.The pentose sugar joined to the nitrogen base is ribose in nucleotides of RNA and deoxyribose in DNA. The only difference between the sugars is the lack نقص of an oxygen atom on carbon 2 in deoxyribose.The only difference between the sugars is the lack نقص of an oxygen atom on carbon 2 in deoxyribose. The nucleic acid strand is a polymer of nucleotides

62 phosphodiesterPolynucleotides are synthesized by connecting the sugars of one nucleotide to the phosphate of the next with a phosphodiester link. sugar-phosphateThis creates a repeating backbone of sugar-phosphate units with the nitrogen bases as appendages. The sequence of nitrogen bases along a DNA or mRNA polymer is unique for each gene. Genes are normally hundreds to thousands of nucleotides long. الترتيب التتابعى يُحددترتيب الأحماض الأمينيةThe linear order الترتيب التتابعى of bases in a gene specifies يُحدد the order of amino acids ترتيب الأحماض الأمينية ( the monomers of a protein ).

63 An RNA molecule is single polynucleotide chain (single strand).An RNA molecule is single polynucleotide chain (single strand). DNA molecules have two polynucleotide strands (double strand) that spiral around to form a double helix حلزون مزدوج.DNA molecules have two polynucleotide strands (double strand) that spiral around تدور حلزونيا to form a double helix حلزون مزدوج. Inheritance is based on replication of the DNA double helix

64 The sugar-phosphate backbones of the two polynucleotides are on the outside of the helix.The sugar-phosphate backbones of the two polynucleotides are on the outside of the helix. Pairs of nitrogenous bases (one from each strand) connect the polynucleotide chains with hydrogen bonds.Pairs of nitrogenous bases (one from each strand) connect the polynucleotide chains with hydrogen bonds. Most DNA molecules have thousands to millions of base pairs زوج من القواعد (bP).Most DNA molecules have thousands to millions of base pairs زوج من القواعد (bP).

65 Because of their shapes, only some bases are compatible with each other.Because of their shapes, only some bases are compatible متوافقة with each other. –Adenine (A) always pairs with thymine (T) and guanine (G) with cytosine (C). With these base-pairing rules, if we know the sequence of bases on one strand, we know the sequence on the opposite strand.With these base-pairing rules, if we know the sequence of bases on one strand, we know the sequence on the opposite المقابل strand. The two strands are complementary.The two strands are complementary مكملين لبعضهما. During preparations for cell division each of the strands serves as a template to order nucleotides into a new complementary strand.During preparations for cell division each of the strands serves as a template قالب نسخ to order nucleotides into a new complementary strand. This results in two identical copies of the original double-stranded DNA molecule.This results in two identical copies نسختين طبق الأصل of the original double-stranded DNA molecule. –The copies are then distributed to the daughter cells. –The copies are then distributed توزع to the daughter cells. This mechanism ensures that the genetic information is transmitted to the new cells.This mechanism ensures that the genetic information is transmitted to the new cells.

66 Repeated Sugar - Phosphate Sugar–Phosphate-BaseSugar–Phosphate-Base PolynucleotidePolynucleotide DNA backbone One nucleotide DNA Molecule DNA Double stranded RNA single stranded TCGATAG AGTCTAC UUmRNA DNA

67 A TOUR OF THE CELL Panoramic View of the Cell

68 Cell Theory 1- All organisms are composed of one or more of cells. 2- Cell is the basic unit of life. 3- The new cell arises only from pre-existing الموجودة cell. الموجودة cell.

69 The Cell The Organism’s Basic Unit of Structure and Function ProkaryoticProkaryotic EukaryoticEukaryotic Types of cells Micro-organisms All other forms of life Cellulae (Small room) بدائية الكائنات الدقيقة متقدمة

70 All cells are surrounded by a plasma membrane غشاء بلازمى.All cells are surrounded by a plasma membrane غشاء بلازمى. The semi-fluid substance المادة النصف سائلة within the cell is the cytosol, السيتوبلازم containing the cell organelles عِضيات الخلية.The semi-fluid substance المادة النصف سائلة within the cell is the cytosol, السيتوبلازم containing the cell organelles عِضيات الخلية. All cells contain chromosomes which have genes in the form of DNA.All cells contain chromosomes which have genes in the form of DNA. All cells also have Ribosomes, tiny organelles عضيات صغيرة that make proteins using the instructions التعليمات contained in genes.All cells also have Ribosomes, tiny organelles عضيات صغيرة that make proteins using the instructions التعليمات contained in genes. Prokaryotic and eukaryotic cells differ in size and complexity Similarities Similarities أوجه التشابه

71 A major difference الفرق الأساسى between prokaryotic and eukaryotic cells is the location of chromosomes موضع الصبغيات.A major difference الفرق الأساسى between prokaryotic and eukaryotic cells is the location of chromosomes موضع الصبغيات. –In an eukaryotic cell, chromosomes are contained in a true nucleus (النواة ). –In a prokaryotic cell, the DNA is concentrated in the nucleoid (شـبه نواة) without a membrane ( بدون غـشاء) separating it from the rest of the cell. –In prokaryotic cell, DNA is a single strand (أحادى الشريط) or double strand (ثنائى الشريط) DNA. But in eukaryotic cell, DNA is double strand. Prokaryotic and eukaryotic cells differ in size and complexity Differences Differences أوجه الإختلاف

72 Eu: True Karyon: Nucleus Animal Cell Plant Cell What are the functions of cell organelles ? Eukaryotic Cell

73 ميتوكوندريا غشاء بلازمى حهاز جولـﭽـى ريبوسوم الهيكل الخلوى جسم مُحلل جسم مركزى سوط حركى الشبكة الإندوبلازمية النواة المادة الوراثية نوية الجدار النووى حلمات دقيقة

74 The Cell Organelles عضيــات الخليـــــــــة

75 a. Nuclear envelopea. Nuclear envelopeStructure: The nucleus is separated from the cytoplasm by a double membrane غشاء مزدوج.The nucleus is separated from the cytoplasm by a double membrane غشاء مزدوج. Where the double membranes are fused, a pore ثقوب is formedWhere the double membranes are fused, a pore ثقوب is formedFunctions: 1. Pores allows macromolecules to pass through.1. Pores allows macromolecules to pass through. 2. The nuclear membrane الغلاف النووى is maintaining the2. The nuclear membrane الغلاف النووى is maintaining the shape of the nucleus shape of the nucleus 1. The nucleus - The nucleus contains most of the genes in an eukaryotic cell. - The nucleus averages about 5 µm in diameter.

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77 b. Chromatinb. ChromatinStructure: Within the nucleus, the DNA and associated proteins are organized into fibrous material, chromatin.Within the nucleus, the DNA and associated proteins are organized into fibrous material, chromatin. At the time of division, the chromatin fibers coil up تلتف to be seen as separate structures, chromosomes.At the time of division, the chromatin fibers coil up تلتف to be seen as separate structures, chromosomes. Each eukaryotic species has a characteristic number of chromosomes رقم مُمَيـٍز من الكروموسومات.Each eukaryotic species has a characteristic number of chromosomes رقم مُمَيـٍز من الكروموسومات. - A typical human cell has 46 chromosomes (23 pairs), but sex - A typical human cell has 46 chromosomes (23 pairs), but sex cells (ovum and sperm) have only 23 chromosomes. cells (ovum and sperm) have only 23 chromosomes.Functions: 1. Chromatin have genes that determine تحدد the general characters الصفات العامة of organism. characters الصفات العامة of organism. 2. The nucleus directs protein synthesis by synthesizing messenger RNA (mRNA). messenger RNA (mRNA). –The mRNA travels to the cytoplasm and combines with ribosomes where the primary structure of a specific protein is formed.

78 c. Nucleolus Nucleolus is a dark region involved in the production of ribosomes.Nucleolus is a dark region involved in the production of ribosomes.

79 rRNA)Ribosomes contain ribosomal RNA (rRNA) and protein. وحدتينتتحد تخليق البروتينA ribosome is composed of two subunits وحدتين that combine تتحد to direct protein synthesis تخليق البروتين. 2. Ribosomes مرتبطة حرة

80 In the nucleolus, ribosomal RNA (rRNA) is synthesized into ribosomal subunits (rRNA + proteins).In the nucleolus, ribosomal RNA (rRNA) is synthesized into ribosomal subunits (rRNA + proteins). The subunits pass from the nuclear pores to the cytoplasm where they combine to form ribosomes.The subunits pass from the nuclear pores to the cytoplasm where they combine to form ribosomes. - Cell types that synthesize large quantities of proteins (e.g.,- Cell types that synthesize large quantities of proteins (e.g., pancreas) have large numbers of ribosomes. pancreas) have large numbers of ribosomes. Ribosomes are 2 types:-Ribosomes are 2 types:- 1.Free ribosomes معلق 1.Free ribosomes are suspended معلق in the cytosol and synthesize proteins that function within the cytosol. 2.Bound ribosomes ملتصق 2.Bound ribosomes are attached to ملتصق بـ the outside of the endoplasmic reticulum. –This type of ribosomes synthesize proteins that are either included into membranes or for secretion outside the cell.

81 3- The Endomembrane System a)The endoplasmic reticulum manufacturers membranes and performs many other biosynthetic functions b)The Golgi apparatus finishes, sorts, and ships cell products c)The Lysosomes are digestive compartments d) The Vacuoles have diverse functions in cell maintenance

82 a)- Endoplasmic reticulum manufacturers membranes and performs many other biosynthetic functions The ER includes membranous tubulesThe ER includes membranous tubules There are two types of ER that differ in structure and function.There are two types of ER that differ in structure and function. 1.Smooth ER looks smooth because it lacks ribosomes. 2.Rough ER looks rough خشنة because ribosomes (bound ribosomes) are attached to its membranes, including the outside of the nuclear envelope.

83 The smooth ER:The smooth ER: - It is rich in enzymes and plays a role in metabolic processes. الهرمونات الحنسية - Its enzymes synthesize lipids دهون (oils, phospholipids, and steroids) including the sex hormones الهرمونات الحنسية. توجد بكثرةإبطال الأثر السام المخدراتالسموم - Extensive توجد بكثرة in the liver, it helps detoxify إبطال الأثر السام drugs المخدرات and poisons السموم The rough ER:The rough ER: it contains ribosomes - is the main site of protein synthesis. متوفرة - It is especially abundant متوفرة in those cells that secrete proteins. - These secretory proteins are packaged in transport vesicles that carry them to their next stage.

84 أوعية ناقلة تطويرMany transport vesicles أوعية ناقلة from the ER travel to the Golgi apparatus for modification تطوير of their contents. تصنيع تغليفتـَجْهيز PackagingThe Golgi function is manufacturing تصنيع, warehousing تغليف, sorting تـَجْهيز (Packaging), and shipping نقل materials to outside the cell. خلايا إفرازيةThe Golgi apparatus is extensive specially in secretory cells خلايا إفرازية. The Golgi also manufactures polysaccharides. b)- Golgi apparatus: finishes, sorts تـُجَهز, packaging and ships تنقل cell products

85 وعاء ناقل

86 lysosomeThe lysosome is a membrane-bounded sac of enzymes that digests macromolecules. c)- Lysosomes الأجسام المُحللة are digestive components

87 Lysosomal enzymes can hydrolyse proteins, fats, polysaccharides, and nucleic acids. acidicThese enzymes work best at pH = 5 (acidic). الهضم الذاتىWhile rupturing إنفجار lysosomes can destroy the cell by autodigestion (autophagy) الهضم الذاتى. lysosomal enzymes ER تنقل إلىThe lysosomal enzymes and membrane are synthesized by rough ER and then transferred to تنقل إلى the Golgi then to lysosomes. الفحجوة الغذائيةLysosomes can fuse with food vacuoles الفحجوة الغذائية to digest food, (when a food item is brought into the cell by phagocytosis). recyclingLysosomes can also fuse with another organelle or part of the cytosol. This process of autophagy called recycling which renews the cell

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89 أوعـيةفجوات أكياس ذات أغشيةVesicles أوعـية and vacuoles فجوات are membrane-bound sacs أكياس ذات أغشية with varied functions. 1.Food vacuoles فجوة غذائية 1.Food vacuoles فجوة غذائية, from phagocytosis, fuse with lysosomes. 2.Contractile vacuoles فجوة منقبضة 2.Contractile vacuoles فجوة منقبضة, found in freshwater protists, pump excess water out of the cell. 3.Central vacuolesفجوة مركزية 3.Central vacuoles فجوة مركزية are found in many mature plant cells. الفجواتوظائف متنوعة للحفاظ على الخلية d)- Vacuoles الفجوات have diverse functions وظائف متنوعة in cell maintenance للحفاظ على الخلية

90 Animal cell

91 Peroxisomescontain enzymes that transfer hydrogen from various substrates to oxygenPeroxisomes contain enzymes that transfer hydrogen from various substrates to oxygen –An intermediate product of this process (H 2 O 2 is hydrogen peroxide (H 2 O 2 ), a poison, but the peroxisome has another enzyme that converts H 2 O 2 to water. –Some peroxisomes break fatty acids down to smaller molecules that are transported to لإنتاج الطاقة mitochondria for fuel لإنتاج الطاقة. –They detoxify alcohol and other harmful compounds. Thus, it exists extensively in liver cells the liver cells 1)- Peroxisomes (exists in the liver cells): generate and degrade H 2 O 2 in performing various metabolic functions Other Membranous Organelles 1)- Peroxisomes (exists in the liver cells): generate and degrade H 2 O 2 in performing various metabolic functions

92 Mitochondria organelles converts energy to forms that cells can use for work. Mitochondria تـُنتِج ATP هدم مصادرMitochondria are the sites of cellular respiration, generating تـُنتِج ATP (Adenosine TriPhosphate) from the catabolism هدم of sugars, fats, and other fuel sources مصادر طاقة in the presence of oxygen. Mitochondria are mobile and move around the cell along tracks in the cytoskeleton. Mitochondrium: is the main energy transformer of cells 2- Mitochondrium: is the main energy transformer of cells

93 Mitochondria نتوءاتMitochondria have a smooth outer membrane and a highly folded inner membrane forming cristae نتوءات. mitochondrial matrixThe inner membrane encloses the mitochondrial matrix, a fluid-filled space with DNA, ribosomes, and enzymes.

94 Functions: The cytoskeleton organizes يرتبThe cytoskeleton organizes يرتب the structures and activities of the cell. functions in cell motility.functions in cell motility. The Cytoskeleton الهيكل الخلوى The cytoskeleton is a network of fibers extending throughout تمتد عبر the cytoplasm

95 Cytoskeleton Responsible for cell motility, and separation of chromosome during cell division. () (Tubulin protein) Transport materials within the cell. () (Actin protein) Reinforcing the cell shape and fixing position of organelles. () (Fibrous protein) MicrofilamentsIntermediatefilamentsMicrotubules ThickThinMiddleسميكة رفيعةمتوسطة أنيبيبات دقيقة ألياف دقيقة ألياف متوسطة

96 The cytoskeleton provides mechanical support and maintains shape of the cell.The cytoskeleton provides mechanical support and maintains shape of the cell. The cytoskeleton is dynamic, حركي dismantling يتفكك in one part and reassembling يتركب in another to change cell shape.The cytoskeleton is dynamic, حركي dismantling يتفكك in one part and reassembling يتركب in another to change cell shape. The cytoskeleton also plays a major role in cell motility حركة الخلية by interacting with motor proteins البروتين الحركىThe cytoskeleton also plays a major role in cell motility حركة الخلية by interacting with motor proteins البروتين الحركى. –In cilia, flagella and muscle cells motor proteins pull components of the cytoskeleton past each other.

97 Microtubules functions as tracks قضيب that guide motor proteins to circulates materials within the cell.Microtubules functions as tracks قضيب that guide motor proteins to circulates materials within the cell. Motor molecules carry vesicles or organelles to various destinations إلى أماكن مختلفة inside cell.Motor molecules carry vesicles or organelles to various destinations إلى أماكن مختلفة inside cell. They move chromosomes during cell divisionThey move chromosomes during cell division

98 In many cells, microtubules grow out from a centrosome الجسم المركزى near the nucleus.In many cells, microtubules grow out from a centrosome الجسم المركزى near the nucleus. In animal cells, the centrosome has a pair of centrioles, each with 9 triplets of microtubules تسعة مجموعات كل منها مكون من ثلاثة أنيبيبات arranged in a ring مُرتبة دائريا.In animal cells, the centrosome has a pair of centrioles, each with 9 triplets of microtubules تسعة مجموعات كل منها مكون من ثلاثة أنيبيبات arranged in a ring مُرتبة دائريا.

99 Microtubules are the central structural supports both cilia الأهداب and flagella الأسواط. –Both can move unicellular and small multicellular organisms by propelling water outside the organism. Cilia and Flagella Cilia usually occur in large numbers on the cell surface.Cilia usually occur in large numbers on the cell surface. Flagella usually occur in just one or a few per cell.Flagella usually occur in just one or a few per cell. Cilia move more like oars مجاديف with alternating power and recovery strokes.Cilia move more like oars مجاديف with alternating power and recovery strokes. Flagella have an undulatory movement حركة تموجية.Flagella have an undulatory movement حركة تموجية. So, They differ in their beating pattern أسلوب الحركة.So, They differ in their beating pattern أسلوب الحركة.

100 cilia flagellum

101  Both cilia and flagella have the same ultrastructure التركيب الدقيق.  Both have a core مركز of microtubules sheathed by the plasma membrane.  Nine doublets (9 + 2 pattern) تسعة مجموعات كل منها مكون من أنيبيبتان of microtubules arranged around a pair at the center.  Flexible “wheels” of proteins connect outer doublets to each other and to the core.  The outer doublets are also connected are also connected by motor proteins. by motor proteins.  The structure cilium and flagellum is  The structure of cilium and flagellum is identical to that of identical to that of centriole. centriole.

102 Cilia and flagella are formed of arms of a motor protein (dynein بروتين الداينين ).Cilia and flagella are formed of arms of a motor protein (dynein بروتين الداينين ). –Addition phosphate group from ATP to dynein and its removal causes conformation changes in the protein. –Dynein arms alternately grab, move, and release the outer microtubules. –Protein cross-links limit sliding and the force is expressed as bending.

103 7- Cell membrane The plasma membrane functions as a selective barrier حاجز إختيارى that allows passage of oxygen, nutrients, and wastes for the whole volume of the cell.The plasma membrane functions as a selective barrier حاجز إختيارى that allows passage of oxygen, nutrients, and wastes for the whole volume of the cell.

104 Cell membrane Composed of lipids (phospholipids) and proteins Lipid layer contains hydrophilic and hydrophobic regions Phospholipid Hydrophilic مُحب للماء Hydrophobic كاره للماء Proteins Carbohydrate chains

105 CHAPTER 5 THE STRUCTURE AND FUNCTION OF MACROMOLECULES MEMBRANE STRUCTURE AND FUNCTION How things get into and out of the cell

106  The plasma membrane separates the living cell from its nonliving surroundings.  This thin barrier, 8 nm thick, controls traffic into and out of the cell.  Like other membranes, the plasma membrane is selectively permeable, allowing some substances to cross more easily than others.  The main macromolecules in membranes are lipids and proteins, but include some carbohydrates.  The most abundant lipids are phospholipids.  Phospholipids and most other membrane constituents are amphipathic molecules. Amphipathic molecules have both hydrophobic regions and hydrophilic regions. Amphipathic molecules have both hydrophobic regions and hydrophilic regions.  The phospholipids and proteins in membranes create a fluid mosaic model. proteins embedded or attached to a double layer of phospholipids. proteins embedded or attached to a double layer of phospholipids. Section A: Membrane Structure

107 Fig. 8.1b Fig. 8.2b  The molecules in the bilayer طبقة مزدوجة are arranged as hydrophobic fatty acid tails are sheltered محمية from water while the hydrophilic phosphate groups interact with water.  Membrane proteins are amphipathic, with hydrophobic and hydrophilic regions.  If at the surface, the hydrophilic regions would be in contact with water.  In this fluid mosaic model, the hydrophilic regions of proteins and phospholipids are in contact with water and the hydrophobic regions are in a nonaqueous environment.

108 Most of the lipids and some proteins can drift laterally in the plane of the membrane, but rarely flip-flop from one layer to the other.Most of the lipids and some proteins can drift laterally in the plane of the membrane, but rarely flip-flop from one layer to the other. The lateral movements of phospholipids are rapid, about 2 µm/second.The lateral movements of phospholipids are rapid, about 2 µm/second. Many larger membrane proteins move more slowly but do drift.Many larger membrane proteins move more slowly but do drift. As temperatures cool, membranes switch from a fluid state to a solid state as the phospholipids are more closely packed.As temperatures cool, membranes switch from a fluid state to a solid state as the phospholipids are more closely packed. Membranes rich in unsaturated fatty acids are more fluid than those dominated by saturated fatty acids because the kinks in the unsaturated fatty acid tails prevent tight packing.Membranes rich in unsaturated fatty acids are more fluid than those dominated by saturated fatty acids because the kinks in the unsaturated fatty acid tails prevent tight packing. To work properly with permeability, membrane must be fluid, about as fluid as oil.To work properly with permeability, membrane must be fluid, about as fluid as oil. Cell membrane is fluid

109 A membrane is a collage تـَجَمُّع of different proteins embedded مُـنْغَمِس in the fluid matrix of the lipid bilayer.A membrane is a collage تـَجَمُّع of different proteins embedded مُـنْغَمِس in the fluid matrix of the lipid bilayer. Membranes are mosaics of structure and function

110 Periphera l proteins Integral proteins A)- The plasma membrane has a unique collection تجمع مميَـز of proteins. There are two populations of membrane proteins.There are two populations of membrane proteins. 1.Integral proteins مُندَمج penetrate the hydrophobic core of the lipid bilayer (transmembrane protein). 2.Peripheral proteins طرفى are not embedded in the lipid bilayer at all. Instead, they are loosely bounded to the surface of the integral proteins. The integral proteins has a middleThe integral proteins has a middle area, hydrophobic regions with nonpolar amino acids. And surface area, in contact with the aqueous environment, they have hydrophilic regions of amino acids.And surface area, in contact with the aqueous environment, they have hydrophilic regions of amino acids.

111 The proteins in the plasma membrane may provide a variety of major cell functions.The proteins in the plasma membrane may provide a variety of major cell functions.

112 The membrane plays the key role in cell-cell recognition.The membrane plays the key role in cell-cell recognition. –Cell-cell recognition is the ability of a cell to distinguish one type of neighboring المجاورة cell from another. –It is the basis for rejection of foreign cells by the immune system. –Cells recognize other cells by recognizing the surface molecules, often carbohydrates, on the plasma membrane. –Membrane carbohydrates may be covalently bonded either to lipids, forming glycolipids, or, to proteins, forming glycoproteins. –The four human blood groups (A, B, AB, and O) differ in the external carbohydrates on red blood cells. B)- Membrane carbohydrates are important for cell-cell recognition

113  A steady traffic العبور المنتطم of small molecules and ions move across the plasma membrane in both directions.  For example, sugars, amino acids, and other nutrients enter a muscle cell and metabolic waste products leave it.  The cell absorbs O 2 and expels CO 2.  It also regulates concentrations of inorganic ions, like Na +, K +, Ca 2+, and Cl -, by passing them across the membrane.  However, substances do not move across the membrane barrier indiscriminately عشوائيا.  Hydrophobic molecules, like hydrocarbons, CO 2, and O 2, can dissolve in the lipid bilayer and cross easily.  Ions and polar molecules, like water, glucose and sugars pass through with difficulty.  Proteins can assist and regulate the transport of ions and polar molecules.  Proteins can assist and regulate يساعد و ينظم the transport of ions and polar molecules. 1- Selective permeability functions of cell membrane (Plasma membrane) 1- Selective permeability النفاذية الإختيارية one of the most important functions of cell membrane (Plasma membrane)

114 CO 2 O2O2O2O2 O2O2O2O2 NucleusNucleus Selective Permeability take up exclude تـتجنب The cell is able to take up تـنـتـقى particular molecules and exclude تـتجنب others

115 Diffusion: الإنتشارDiffusion: الإنتشار Is the tendency إستعداد of molecules of any substance to spread out للإنتشار in the available space randomly عشوائيا. Is the tendency إستعداد of molecules of any substance to spread out للإنتشار in the available space randomly عشوائيا. For example, a permeable membrane غشاء منفذ separating a solution with dye molecules from pure water, dye molecules will cross the barrier randomly.For example, a permeable membrane غشاء منفذ separating a solution with dye molecules from pure water, dye molecules will cross the barrier randomly. The dye will cross the membrane until both solutions have equal concentrations of the dye (dynamic equilibrium).The dye will cross the membrane until both solutions have equal concentrations of the dye (dynamic equilibrium التعادل الديناميكى ). 2- Passive transport is diffusion across a membrane 2- Passive transport الإنتقال السلبى is diffusion across a membrane

116 A substance will diffuse from where it is more concentrated to where it is less concentrated, down its concentration gradient.A substance will diffuse from where it is more concentrated to where it is less concentrated, down its concentration gradient مـُنحدر التركيز. Passive transport:الإنتقال السلبى Passive transport: الإنتقال السلبى is the diffusion of a substance across a biological membrane which requires no energy. is the diffusion of a substance across a biological membrane which requires no energy. The concentration gradient drives diffusion. The concentration gradient drives diffusion.

117 Differences in concentration of dissolved materials in two solutions can lead to the movement of ions from one to the other.Differences in concentration of dissolved materials in two solutions can lead to the movement of ions from one to the other. The solution with the higher concentration of solutes is hypertonic.The solution with the higher concentration of solutes is hypertonic. The solution with the lower concentration of solutes is hypotonic.The solution with the lower concentration of solutes is hypotonic. Solutions with equal solute concentrations are isotonic.Solutions with equal solute concentrations are isotonic. Osmosis:Osmosis: Is a passive transport in which water diffuses across a selectively permeable membrane from the hypotonic solution to the hypertonic solution until the solutions become isotonic. Is a passive transport in which water diffuses across a selectively permeable membrane from the hypotonic solution to the hypertonic solution until the solutions become isotonic. Osmosis الأسموزية : is the passive transport of water

118 Low conc. of sugar High conc. of sugar Selectively permeable membrane Principal of water movement hypotonic hypertonic IsotonicOsmosisOsmosis

119 Passive transport of water () Passive transport of water ( Osmosis ) Hypertonic solution: contains high concentration of solute مُذاب molecules.Hypertonic solution: عالى التركيز contains high concentration of solute مُذاب molecules. Hypotonic solution: contains low concentration of solute molecules.Hypotonic solution: منخفض التركيز contains low concentration of solute molecules. Isotonic solution: contains equal concentrations of solute moleculesIsotonic solution: متعادل contains equal concentrations of solute molecules Biological MembraneHypotonicHypertonic H2OH2OH2OH2O

120 A cell in a hypotonic solution will gain تسحب water, swell, and burst.A cell in a hypotonic solution will gain تسحب water, swell, and burst. The cell in a hypertonic environment will loose water, shrivel تنكمش, and die.The cell in a hypertonic environment will loose water, shrivel تنكمش, and die. Organisms without rigid walls have osmotic problems in either a hypertonic or hypotonic environment and must have adaptations for osmoregulation to maintain للحفاظ على their internal environment.Organisms without rigid walls have osmotic problems in either a hypertonic or hypotonic environment and must have adaptations for osmoregulation to maintain للحفاظ على their internal environment. Example, Paramecium have a specialized organelle (the contractile vacuole), that functions as a pump to force يطرد water out of the cell.Example, Paramecium have a specialized organelle (the contractile vacuole), that functions as a pump to force يطرد water out of the cell. Osmoregulation Osmoregulation التوازن الأسموزى

121 Many polar molecules and ions diffuse passively through the lipid bilayer with the help of transport proteins (gated channels ).Many polar molecules and ions diffuse passively through the lipid bilayer with the help of transport proteins (gated channels قنوات مُبَوبة ). The passive movement of molecules down its concentration gradient via a transport protein is called facilitated diffusion.The passive movement of molecules down its concentration gradient via a transport protein is called facilitated diffusion. Specific proteins facilitate passive transport Specific proteins facilitate تـُسَهـِّل passive transport Many transport proteins simply provide channels allowing a specific molecule or ion to cross the membrane.Many transport proteins simply provide channels allowing a specific molecule or ion to cross the membrane. Other transport proteins translocate ينقل the molecules across the membrane as the protein changes shape (active transport)Other transport proteins translocate ينقل the molecules across the membrane as the protein changes shape (active transport)

122 Active Transport النقل النشط

123 Some facilitated transport proteins can move solutes against their concentration gradient, from the side where they are less concentrated to the side where they are more concentrated.Some facilitated transport proteins can move solutes against their concentration gradient, from the side where they are less concentrated to the side where they are more concentrated. This active transport requires metabolic energy via ATP.This active transport requires metabolic energy via ATP. Active transport is the pumping of solutes against their concentration gradients تزايد Active transport is the pumping ضَخ of solutes against their concentration gradients تزايد التركيز Active transport is critical بالغ الأهمية for a cell to maintain its internal concentrations. Active transport is performed by specific proteins embedded in the membranes (transport protein).

124 The sodium-potassium pump actively maintains the gradient of sodium (Na + ) and potassium ions (K + ) across the membrane.The sodium-potassium pump actively maintains the gradient of sodium (Na + ) and potassium ions (K + ) across the membrane. –The animal cell has higher concentrations of K + and lower concentrations of Na + inside the cell. –The sodium-potassium pump (T. protein) uses the energy of one ATP to pump 3 Na + ions out and 2 K + ions in. 1)- Small moleculesIons) 1)- Small molecules (Ions ) High conc. of K + High conc. of Na + Low conc. of K + Low conc. of Na + 1ATP 3 2 T. protein Na Cellular membrane Protein molecule Inside the cell Outside the cell ATP Na Na Na Na Na Na

125 Adenosine Tri-Phosphate (ATP) PPP P PPPP + H 2 O EnergyEnergy Adenosine Triphosphate Adenosine Di-Phosphate

126

127 down their concentration gradient against their concentration gradient Both diffusion and facilitated diffusion are forms of passive transport of molecules down their concentration gradient, while active transport requires an investment of energy to move molecules against their concentration gradient. Two roles of membrane protein

128  Small molecules and water enter or leave the cell through the lipid bilayer or by transport proteins.  Large molecules, such as polysaccharides and proteins, cross the membrane by vesicles.  Large molecules, such as polysaccharides and proteins, cross the membrane by vesicles أوعية. 1.Exocytosis الإخراج الخلوى: a transport vesicle budded from ينشأ من the Golgi apparatus is moved by the cytoskeleton to the plasma membrane. a transport vesicle budded from ينشأ من the Golgi apparatus is moved by the cytoskeleton to the plasma membrane. When the two membranes come in contact تلامس, the bilayers fuse يندمج and spill يُفرع the contents to the outside. When the two membranes come in contact تلامس, the bilayers fuse يندمج and spill يُفرع the contents to the outside. Endocytosis الإدخال الخلوى a cell brings in macromolecules and particulate matter by forming new vesicles from the plasma membrane and include the following: 2- Endocytosis الإدخال الخلوى, a cell brings in macromolecules and particulate matter by forming new vesicles from the plasma membrane and include the following: Large molecules are transported by Exocytosis and endocytosis 2)- Large molecules () 2)- Large molecules (macromolecules)

129 A)- Phagocytosis الإبتلاع : A)- Phagocytosis الإبتلاع الخلوى : Called “cellular eating”. The cell engulfs a particle by extending pseudopodia أقدام كاذبة around it and packaging it تـُغلفها in a large vacuole. Called “cellular eating”. The cell engulfs تـَبْلَع a particle by extending pseudopodia أقدام كاذبة around it and packaging it تـُغلفها in a large vacuole. The contents of the vacuole are digested when the vacuole fuses with a lysosome.The contents of the vacuole are digested when the vacuole fuses with a lysosome.

130 B)- Pinocytosis, “cellular drinking”, B)- Pinocytosis, الشرب الخلوى “cellular drinking”, a cell creates a vesicle around droplets نقاط of extracellular fluid السائل الموجود خارج الخلية. a cell creates a vesicle around droplets نقاط of extracellular fluid السائل الموجود خارج الخلية. –This is a non-specific process عملية غير متخصصة.

131 C)- Receptor-mediated endocytosis: C)- Receptor-mediated endocytosis: الإدخال الخلوى عن طريق المستقبلات المتخصصة It Is called whichvery specific in what substances are being transported. It Is called ( Selective eating ) which very specific in what substances are being transported. It is triggered تـُستـَحث when extracellular substances bind to special receptors مُستقبـِلات خاصة, on the membrane surface. This triggers the formation of a vesicle وعاءIt is triggered تـُستـَحث when extracellular substances bind to special receptors مُستقبـِلات خاصة, on the membrane surface. This triggers the formation of a vesicle وعاء It enables a cell to take large quantities of specific materials that may be in low concentrations in the environment.It enables a cell to take large quantities of specific materials that may be in low concentrations in the environment.

132 Phagocytosis PinocytosisReceptor-mediatedendocytosis Cellular eating Cellular drinking Using specific receptors (coated vesicles) that bind to specific legends and engulf it. It is specific Selective eating Transport PassiveActive DiffusionFacilitateddiffusion LargemoleculesSmallMolecules/ions (T. protein) (Membrane) (Membrane) ExocytosisEndocytosis

133 CHAPTER 5 THE STRUCTURE AND FUNCTION OF MACROMOLECULES Pages 96 - 103 INTRODUCTION TO METABOLISM Section B: Enzymes 1.Enzymes speed up metabolic reactions by lowering energy barriers 2.Enzymes are substrate specific 3. The active site in an enzyme’s catalytic center 4. A cell’s physical and chemical environment affects enzyme activity

134 Hydrolysis of sucrose () Hydrolysis of sucrose ( table sugar ) Glucose + Fructose SucroseDehydration Hydration (H 2 O) Sucrase Glucose + Fructose sucrosein the presence of Sucrase Hydrolysis of sucrose in the presence of Sucrase results in its two monosaccharide components. This process include: 1- breaking the bond between Glucose and Fructose; 2- Then, forming new bonds with H + and OH - from water This process consumes تستهلك energy ( E A ) This process consumes تستهلك energy ( Activation Energy; E A )

135 A catalyst المُحفز is a chemical agent that changes the rate of a reaction without being consumed دون أن يُستهلك by the reaction. An enzyme is a catalytic protein. Chemical reactions between molecules involve both bond breaking and bond forming. To hydrolyze (hydration) sucrose, the bond between glucose and fructose must be broken via hydrolysis in the presence of sucrase ( ). To hydrolyze (hydration) sucrose, the bond between glucose and fructose must be broken via hydrolysis in the presence of sucrase (the catalyst). Enzymes speed up metabolic reactions by lowering energy barriers Enzymes speed up metabolic reactions by lowering energy barriers حواجز الطاقة Sucrase

136 Catalyst: is a chemical agent that accelerate the reaction without being consumed by the reaction. Enzyme is a catalytic protein بروتين مساعد/محفز Activation Energy: is the amount of energy needed for the reaction ( between enzyme & substrate) to complete () Activation Energy: is the amount of energy needed for the reaction ( between enzyme & substrate) to complete ( to break the bonds ) Raising the temperature for these reactions to complete will either denature the compounds or kill the cell. Thus, organisms must therefore use a catalyst عامل محفز. Enzymes and Activation Energy Enzyme is a specific متخصص catalyst for specific reactants at any time in the cell (). Enzyme is a specific متخصص catalyst for specific reactants at any time in the cell ( e.g. Sucrase for only Sucrose ).

137 Activation energy: is the amount of energy necessary to push the reactants over an energy barrier. At the transition state, the molecules are at an unstable point. The difference between free energy of the products and the free energy of the reactants is the delta G. Enzyme speed reactions by lowering E A. The transition state can then be reached even at moderate temperatures.

138 The substrate المادة المطلوب هضمها is a reactant which binds to an enzyme.The substrate المادة المطلوب هضمها is a reactant which binds to an enzyme. When a substrate binds to an enzyme, the enzyme catalyzes يسهل the conversion تحويل of the substrate to the product مكوناتها البنائية.When a substrate binds to an enzyme, the enzyme catalyzes يسهل the conversion تحويل of the substrate to the product مكوناتها البنائية. –Sucrase () is an enzyme that binds to sucrose () and breaks the disaccharide into fructose and glucose (). –Sucrase (catalyst) is an enzyme that binds to sucrose (substrate) and breaks the disaccharide into fructose and glucose (products). Enzymes are substrate specific Substrate Product (s) Enzyme (a catalyst) Sucrose + H 2 O Sucrase Glucose + Fructose Specificity of enzyme تخصصية الإنزيم refers to its Active Site المركز النشط which fit to يـُناسب the surface of substrate.

139 The active site of an enzymes is typically a pocket or groove شكل الجيب on the surface of the enzyme into which the substrate fits. The specificity of an enzyme is due to the fit between the active site and that of the substrate. As the substrate binds, the enzyme changes shape to fit the substrate, bringing chemical groups in position to catalyze the reaction. Fig. 6.14 The active site is an enzyme’s catalytic center

140 Catalytic Cycle of Enzyme

141 Active site of enzyme and Catalytic Cycle Sucrase Sucrose Glucose Fructose H2OH2OH2OH2O

142 1- The substrate binds to the active cite of enzyme. 2- This forms an Enzyme-Substrate complex ( via weak hydrogen bonds ). 3- The active cite catalyses the conversion of the substrate to final products (original components) by breaking bonds. 4- The resulting products release from the enzyme. 5- The enzyme starts another reaction over and over again. 6- Thus, the enzyme can have a huge metabolic effects in the catalytic cycle. Catalytic Cycle of Enzyme

143 A single enzyme molecule can catalyze thousands or more reactions a second. Enzymes are unaffected by the reaction and are reusable يـُعاد استخدامها. Most metabolic enzymes الإنزيمات الأيضية can catalyze a reaction in both the forward and reverse direction. The actual direction depends on the relative concentrations of products and reactants. Enzymes catalyze reactions in the direction of equilibrium التعادل. Enzymes lower activation energy and speed a reaction. The rate that a specific number of enzymes converts substrates to products depends in part on substrate concentrations. At some substrate concentrations, the active sites on all enzymes are engaged مشغولة, called enzyme saturation التشبع الإنزيمى.

144 Some conditions lead to the most active conformation and lead to optimal rate of reaction. These factors are:-Some conditions lead to the most active conformation and lead to optimal rate of reaction. These factors are:- Cellular factors affecting enzyme activity 1.Temperature: has a major impact on reaction rate.  As temperature increases, reaction between substrate and active sites occur faster.  However, at some point thermal increase begins to denature the substrate.  Each enzyme has an optimal temperature درجة حرارة مُثلى.

145 3. Cofactors ( ): العوامل المساعدة 3. Cofactors ( coenzymes): العوامل المساعدة A non-protein helpers for catalytic activity of enzymes. They bind permanently دائما to the enzyme and include two types:- A non-protein helpers for catalytic activity of enzymes. They bind permanently دائما to the enzyme and include two types:- a) Inorganic cofactors, include zinc, iron, and copper. a) Inorganic cofactors, include zinc, iron, and copper. b) Organic cofactors, include vitamins or molecules derived from vitamins. b) Organic cofactors, include vitamins or molecules derived from vitamins. 2. pH also influences the reaction rate, each enzyme has an optimal pH falls between pH 6 - 8 for most enzymes. However, digestive enzymes in the stomach are designed to work best at pH 2 while those in the intestine are optimal at pH 8, both matching their working environments.However, digestive enzymes in the stomach are designed to work best at pH 2 while those in the intestine are optimal at pH 8, both matching their working environments. Fig. 6.16b, page 100 Cellular factors affecting enzyme activity

146 They are molecules that prevent enzymes from catalyzing reactions. –If thy covalently bind with enzyme, inhibition is irreversible غير منعكس. –If binding is weak, inhibition may be reversible مُنعكس. If the inhibitor binds to the same site as the substrate, then it called competitive inhibition تثبيط تنافسى.If the inhibitor binds to the same site as the substrate, then it called competitive inhibition تثبيط تنافسى. Enzyme inhibitors: مُـثـبِّطات الإنزيمات If the inhibitor binds somewhere other than the active site, then it called noncompetitive inhibition. If the inhibitor binds somewhere other than the active site, then it called noncompetitive inhibition.

147 Types of Inhibitors: A- Competitive: That resemble the substrate molecule and thus competes the attach to the active site (blocking the active site). B- Noncompetitive: They do not compete the substrate directly at the active site. Rather, they bind with another part of the enzyme resulting in changing enzyme shape. Finally, deactivate يـُخمد the active site. The insecticide DDT is inhibitor for key enzymes of nervous system. Many antibiotics (e.g. Penicillin) inhibits enzymes that help bacteria to make their cell walls. Activation and inhibition of enzymes are essential for metabolic control

148 CHAPTER 5 THE STRUCTURE AND FUNCTION OF MACROMOLECULES The Control of Metabolism 1.Metabolic control often depends on allosteric regulation 1.Metabolic control often depends on allosteric regulation التحكم الجانبى 2.The localization of enzymes within a cell helps order metabolism

149 The control of metabolism The control of metabolism ( i.e. enzyme activity ) 1)- Allosteric Regulation : The cell is controlling its metabolism by regulating enzyme activity: Regulatory molecules that bind weakly to an Alosteric site of the enzyme (Allosteric Enzymes) in order to inhibit or stimulate the enzyme activity. A)- Allosteric activator. B)- Allosteric inhibitor C)- Feedback inhibition. 2- Cooperativity. Stabilizes favorable conformational changes at all other subunits to make enzyme more efficient.

150 In many cases, the molecules that naturally regulate enzyme activity behave like reversible noncompetitive inhibitors or activators.In many cases, the molecules that naturally regulate enzyme activity behave like reversible noncompetitive inhibitors or activators. These molecules often bind weakly to an allosteric site which is a specific receptor on the enzyme that is not the active site.These molecules often bind weakly to an allosteric site which is a specific receptor on the enzyme that is not the active site. These molecules can either inhibit or stimulate enzyme activity.These molecules can either inhibit or stimulate enzyme activity. Metabolic control often depends on allosteric regulation 1)- Allosteric Regulation: 1)- Allosteric Regulation: التنظيم الألوستيرى Most allosterically regulated enzymes are constructed of two or more polypeptide chains.Most allosterically regulated enzymes are constructed of two or more polypeptide chains. Each subunit has its own active site. The allosteric sites are often located where subunits are joined.Each subunit has its own active site. The allosteric sites are often located where subunits are joined. The whole protein exists in two conformational shapes, one is active, and one is inactive.The whole protein exists in two conformational shapes, one is active, and one is inactive. Allosteric site

151 A)- Allosteric activators : A)- Allosteric activators منشطات : It makes active site functional (connection of substrate with enzyme). It makes active site functional (connection of substrate with enzyme). B)- Allosteric inhibitors : B)- Allosteric inhibitors مثبطات : It makes active site non- functional. It makes active site non- functional. In many cases, both inhibitors and activators are similar enough in shape that they compete for the same allosteric sites.In many cases, both inhibitors and activators are similar enough in shape that they compete for the same allosteric sites. –These molecules may be products and substrates of a metabolic pathway. –For example, some catabolic pathways have allosteric sites that are inhibited when ATP binds, but activated when AMP (adenosine monophosphate) binds. –When ATP levels are low, AMP levels are high, and the pathway is turned on until ATP levels rise, AMP levels fall and inhibition by ATP occurs.

152 C)- Feedback inhibition التثبيط بالأثر الراجعى : It is one of the common methods of metabolic control in which a metabolic pathway is turned off يتوقف by its end product الناتج النهائى. It is one of the common methods of metabolic control in which a metabolic pathway is turned off يتوقف by its end product الناتج النهائى. Example:Example: the production of Isoleucine from Thereonine by Thereonine deaminase:- the production of Isoleucine from Thereonine by Thereonine deaminase:- The end product acts as an inhibitor of an enzyme in the pathway.The end product acts as an inhibitor of an enzyme in the pathway. When the product is abundant متوفر, the pathway is turned off, when rare قليل the pathway is active.When the product is abundant متوفر, the pathway is turned off, when rare قليل the pathway is active.

153 2)- Cooperativity regulation التنظيم التضامنى It occurs In enzymes with multiple catalytic subunits, binding by a substrate to one active site stabilizes favorable conformational changes at all other subunits, a process called cooperativity التضامنية.It occurs In enzymes with multiple catalytic subunits, binding by a substrate to one active site stabilizes favorable conformational changes at all other subunits, a process called cooperativity التضامنية. This mechanism amplifies يـُزيد the response استجابة of enzymes to substrates, making the enzyme to accept additional إضافى substrates.This mechanism amplifies يـُزيد the response استجابة of enzymes to substrates, making the enzyme to accept additional إضافى substrates.

154 Some enzymes and enzyme complexes have fixed locations within the cells as structural components of particular membranes.Some enzymes and enzyme complexes have fixed locations موضع ثابت within the cells as structural components of particular membranes. Others are confined within membrane- enclosed organellesOthers are confined within membrane- enclosed organelles (lysosomes and mitochondria).(lysosomes and mitochondria). Both methods concentrate enzymes for efficiency.Both methods concentrate enzymes for efficiency. لزيادة الفاعلية لزيادة الفاعلية The localization of enzymes within a cell helps order metabolism The localization of enzymes within a cell وضع الإنزيمات بالخلية helps order metabolism تنظيم الأيض

155 Respiration الــدم Alveoli خلايا الجـسـم External respiration Internal respiration Cellular respiration

156 CELLULAR RESPIRATION: HARVESTING CHEMICAL ENERGY Section A: The Principles of Energy Harvest

157 1. Cells recycle the ATP they use for work 2. Redox reactions release energy when electrons move closer to electronegative atoms 2. Redox reactions تفاعلات الأكسدة-الإختزال release energy when electrons move closer to electronegative atoms 3. Electrons “fall” from organic molecules to oxygen during cellular respiration 3. Electrons “fall” تنتقل from organic molecules to oxygen during cellular respiration 4. The “fall” of electrons during respiration is stepwise, via NAD + and an Electron Transport Chain 4. The “fall” of electrons during respiration is stepwise مَرْحَلى, via NAD + and an Electron Transport Chain

158 Respiration

159 Food (Fuel of energy)Food RespirationRespiration O2O2 O2O2EnergyEnergy H2OH2OH2OH2O CO 2 + Cellular Activities Cellular Respiration Organic compounds + O 2 Energy + CO 2 + H 2 O

160 ATP (Adenosine Tri-Phosphate) is the important molecule in cellular energetics.ATP (Adenosine Tri-Phosphate) is the important molecule in cellular energetics عمليات إنتاج الطاقة. –The attachment of three negatively-charged phosphate groups (P) is an unstable, energy-storing arrangement. –The attachment of three negatively-charged phosphate groups (P) is an unstable غير مستقر, energy-storing مخزن للطاقة arrangement. –Loss of the end phosphate group release energy The price of most cellular work is the conversion of ATP to ADP and phosphate (P).The price of most cellular work is the conversion of ATP to ADP and phosphate (P). An animal cell regenerates ATP from ADP by adding P via the catabolism of organic molecules.An animal cell regenerates تعيد إنتاج ATP from ADP by adding P via the catabolism هدم of organic molecules. 1. Cells recycle the ATP they use for work

161 Adenosine Tri-Phosphate (ATP) PPP P PPPP + H 2 O EnergyEnergy Adenosine Triphosphate Adenosine Di-Phosphate

162 The transfer of the terminal phosphate group from ATP to another molecule is phosphorylation. The transfer of the terminal phosphate group from ATP to another molecule is phosphorylation فـَسْـفـَرة. This changes the shape of the receiving molecule in order to work (transport, mechanical, or chemical). When the phosphate groups leaves the molecule, the molecule returns to its original shape (stop).

163 How dose ATP drive cellular work ? MicrotubuleMicrotubule Motor Protein Organelle P Energy P PPPP Cell respiration P

164 Catabolic pathways relocate يبدل أماكن the electrons stored in food molecules, releasing energy that is used to synthesize لتخليق ATP.Catabolic pathways relocate يبدل أماكن the electrons stored in food molecules, releasing energy that is used to synthesize لتخليق ATP. Oxidation-reduction reactions (Redox reactions):Oxidation-reduction reactions (Redox reactions): Are reactions that result in the transfer of one or more electrons from one reactant to another Are reactions that result in the transfer of one or more electrons from one reactant to another Oxidation:Oxidation: Is the loss of electrons. Is the loss فقـد of electrons. Reduction:Reduction: Is the addition of electrons. Is the addition إكتساب of electrons. 2. Redox reactions release energy when electrons move closer to electronegative atoms e-e- XYXY ++ + OxidationReductionEnergy Na + Cl Na + + Cl - Redox reactions require both a donor and acceptor of e. both a donor and acceptor of e.

165 In cellular respiration, glucose and other fuel molecules are oxidized, releasing energy.In cellular respiration, glucose and other fuel molecules are oxidized, releasing energy. Glucose is oxidized, oxygen is reduced, and electrons loose potential energy.Glucose is oxidized, oxygen is reduced, and electrons loose potential energy. H is the source of electrons that transfere to O.H is the source of electrons that transfere to O. Thus, molecules that have an abundance of hydrogen are excellent fuels because their bonds are a source of electrons that “fall” closer to oxygen.Thus, molecules that have an abundance of وفرة من hydrogen are excellent fuels because their bonds are a source of electrons that “fall” closer to oxygen. Enzymes lower the barrier of activation energy, allowing these fuels to be oxidized slowly.Enzymes lower the barrier of activation energy, allowing these fuels to be oxidized slowly. The resulting energy is used by the cell to synthesis ATP.The resulting energy is used by the cell to synthesis ATP. 3. Electrons “fall” from organic molecules to oxygen during cellular respiration C 6 H 12 O 6 + 6O 2 6CO 2 + 6H 2 O + (ATP + Heat) Energy = 686 kcal/mol e -e - Oxidizing agent Reducing agent Energy

166 Cellular respiration does not oxidize glucose in a single step that transfers all the hydrogen in glucose to oxygen at one time.Cellular respiration does not oxidize glucose in a single step that transfers all the hydrogen in glucose to oxygen at one time. Rather, glucose and other fuels are broken down gradually in a series of steps, each catalyzed by a specific enzyme.Rather, glucose and other fuels are broken down gradually تدريجيا in a series of steps, each catalyzed by a specific enzyme. At key steps, hydrogen atoms move from glucose and passed first to the coenzyme NAD + (Nicotinamide Adenine Dinucleotide).At key steps فى الخطوات الأساسية, hydrogen atoms move from glucose and passed first to the coenzyme NAD + (Nicotinamide Adenine Dinucleotide). Dehydrogenase enzymes strip two hydrogen atoms from the fuel (e.g., glucose), pass two electrons to NAD + and release H +.Dehydrogenase enzymes strip two hydrogen atoms from the fuel (e.g., glucose), pass two electrons to NAD + and release H +. 4. The “fall” of electrons during respiration is stepwise, by NAD + and an electron transport chain 4. The “fall” of electrons الإنحدار الإليكترونى during respiration is stepwise مرحلى, by NAD + and an electron transport chain H-C-OH + NAD + C=O + NADH + H + Dehydrogenase

167 This changes the oxidized form, NAD +, to the reduced form NADH. This changes the oxidized form, NAD +, to the reduced form NADH. NAD + functions as the oxidizing agent in many of the redox steps during the catabolism of glucose. NAD + functions as the oxidizing agent in many of the redox steps during the catabolism of glucose. As electrons “fall” from NADH to oxygen, Their energy is tapped to synthesize ATP.

168 Cellular respiration uses an electron transport chain to break the fall of electrons to O 2 into several steps.Cellular respiration uses an electron transport chain سلسلة نقل الإليكترونات to break يـُقـَسم the fall of electrons to O 2 into several steps عدة خطوات. The electron transport chain, consisting of several molecules (), is built into the inner membrane of a mitochondrion.The electron transport chain, consisting of several molecules (primarily proteins), is built into the inner membrane of a mitochondrion. NADH takes electrons from food at the “top” of the chain.NADH takes electrons from food at the “top” of the chain. At the “bottom”, oxygen captures the electrons and H + to form water.At the “bottom”, oxygen captures the electrons and H + to form water. The free energy change from “top” to “bottom” is -53 kcal/mole of NADH.The free energy change from “top” to “bottom” is -53 kcal/mole of NADH. Electrons are passed by increasingly electronegative molecules in the chain until they are caught by oxygen (the most electronegative).Electrons are passed by increasingly electronegative molecules in the chain until they are caught by oxygen (the most electronegative).

169 Electron Fall The Cell Summary of electron “Fall” steps during respiration - Falling of all H atoms from glucose to O is gradually not at once. - It occurs in steps, each one is catalyzed by an enzyme. - H atoms of glucose pass first to the co-enzyme NAD + to form NADH - Then from NAD H to electron transport chain, and finally to O and releases energy to form ATP. MitochondrionMitochondrion Food NADH Transport chain Oxygen NAD + Hee ADPATPEnergy

170 CELLULAR RESPIRATION: HARVESTING CHEMICAL ENERGY Section B: The Process of Cellular Respiration

171 1.Respiration involves glycolysis, the Krebs cycle, and electron transport 2.Glycolysis (): harvests chemical energy by oxidizing glucose (breaking glucose into 2 molecules of pyruvate). 2.Glycolysis ( in cytoplasm ): harvests chemical energy by oxidizing glucose (breaking glucose into 2 molecules of pyruvate). 3. The Krebs cycle (): completes the energy harvest by oxidizing the organic molecules. 3. The Krebs cycle ( in motochonderial matrix ): completes the energy harvest by oxidizing the organic molecules. 4. The electron transport chain ( to synthesisATP. 4. The electron transport chain ( inner mitochondrial membrane ): to synthesis ATP. Cellular respiration generates Cellular respiration generates 38 ATP molecules for each sugar molecule it oxidizes.

172 Summary of Glycolysis ( Splitting of glucose ) It is the process of breaking a glucose into 2 Pyruvate. It is a source for some ATP & NAD H and occurs in the CYTOSOL (cytoplasm). 1)- Glucose is phosphorylated twice by adding 2 P coming from 2 ATP ( substrate-level-phosphorylation ). A)- Energy investment phase It has two phases C 2)- Thus, Glucose (6-C) splits into two small sugar molecules (each with 3-C).

173 dehydrogenase 4)- The resulting e - from the two 3- C -sugar are used for reducing 2 NAD + into 2 NAD H molecules via dehydrogenase. 2 pyruvate 6)- The net yield of this process is the formation of 2 NAD H, 2 ATP and 2 pyruvate molecules. B)- Energy pay-off phase 3)- The two resulting 3- C -sugars are then oxidized (losing e - (H) ). 5)- 4 ATP are formed by adding 4 P to 4ADP molecules. Summary of Glycolysis ( Splitting of glucose ) pyruvate 7)- Now pyruvate is ready for Krebs Cycle.

174 If O 2 is present, pyruvate enters the mitochondrion where enzymes of the Krebs cycle complete the oxidation of this organic fuel to CO 2.If O 2 is present, pyruvate enters the mitochondrion where enzymes of the Krebs cycle complete the oxidation of this organic fuel to CO 2. 2. The Krebs cycle completes the energy harvest by oxidizing organic molecules ( in mitochondrial matrix): As pyruvate enters the mitochondrion which modifies pyruvate to acetyl-CoA which enters the Krebs cycle in the matrix.As pyruvate enters the mitochondrion which modifies pyruvate to acetyl-CoA which enters the Krebs cycle in the matrix. –A carboxyl group is removed as CO 2. –A pair of electrons is transferred from the remaining two-carbon fragment to NAD + to form NADH. –The oxidized fragment, acetate, combines with coenzyme A to form acetyl-CoA.

175 Summary of Respiration - Glycolysis occurs in the cytosol and breaks glucose into 2 pyruvates - Krebs Cycle takes place within the mitochondrial matrix, and breaks a pyruvate into CO 2 and produce some ATP and NAD H. - Electron Transport Chain accepts e - from NAD H and passes these e - from one protein molecule to another. - At the end of the chain, e - combine with both H + and O 2 to form H 2 O and release energy. - These energy are used by mitochondria to synthesis 90% of the cellular ATP via ATP-synthase, a process called Oxidative Phosphorylation, in the inner membrane of mitochondria. - Some of ATP is produced at these tow steps via (substrate-level- phosphorylation).

176 Summary of cell respiration

177 EggLarvaPupaAdult CHEMICAL SIGNALS IN ANIMALS

178 Introduction Nervous and endocrine systems are the main internal communication and regulation systems.Nervous and endocrine systems are the main internal communication and regulation systems. The animal hormone-secreting cells constitute the endocrine system.The animal hormone-secreting cells constitute the endocrine system. Hormone secreting organs are called endocrine glands (ductless glands).Hormone secreting organs are called endocrine glands (ductless glands). Hormone is a chemical signal secreted into blood stream and regulates communicating messages within the body.Hormone is a chemical signal secreted into blood stream and regulates communicating messages within the body. Target cell is the site that reached by the hormone to which it responds.Target cell is the site that reached by the hormone to which it responds. Complete changes in the body is regulated by hormones (e.g. metamorphosis in insects).Complete changes in the body is regulated by hormones (e.g. metamorphosis in insects). Types of hormones are [ Polypeptide H., Steroid H. or Amino acid derivatives H ].Types of hormones are [ Polypeptide H., Steroid H. or Amino acid derivatives H ].

179 Many endocrine organs contain specialized nerve cells called neurosecretory cells that secret hormones.Many endocrine organs contain specialized nerve cells called neurosecretory cells that secret hormones. The hormone epinephrine has two functions:The hormone epinephrine has two functions: –As a hormone of the endocrine system. –As a signal in the nervous system. Feedback is common in regulation the activity of both endocrine and nervous systems (homeostasis) ():Feedback is common in regulation the activity of both endocrine and nervous systems (homeostasis) ( Fig. 45.1, page 956 ): –Calcitonin and parathyroid hormones play an important role in maintaining the concentration of the blood calcium constant. –They are secreted from thyroid and parathyroid glands respictively. Hormones regulate the development of invertebrates (e.g. insects)Hormones regulate the development of invertebrates (e.g. insects)

180 Growth factors: Are proteins and polypeptides that stimulate cell proliferationGrowth factors: Are proteins and polypeptides that stimulate cell proliferation Example: nerve growth factor (NGF) affects certain embryonic cells, developing white blood cells, and other kinds of cells.Example: nerve growth factor (NGF) affects certain embryonic cells, developing white blood cells, and other kinds of cells. Nitric oxide (NO):Nitric oxide (NO): –Though a gas, NO is an important local regulator. –When secreted by neurons, it acts as a neurotransmitter. –When secreted by white blood cells, it kills bacteria and cancer cells. –And when secreted by endothelial cells, it dilates the walls of blood vessels. Prostaglandins (PGs): modified fatty acids.Prostaglandins (PGs): modified fatty acids. –PGs secreted by the placenta stimulate uterine contractions during childbirth. –Other PGs play a role in inflammation and the blood flow to the lungs. A variety of local regulators affect neighboring target cells

181 Most chemical signals bind to plasma-membrane proteins, initiating signal-transduction pathways. Mechanism of chemical signaling: The chemical signals secreted by a cell either: a): Bind to a receptor protein on the surface of the target cell. This will trigger signal transduction pathway. For example protein hormones.

182 a): Penetrate the cell and bind to a receptor protein inside the target cell. This also will trigger signal transduction pathway (e.g. steroid hormones for synthesizing a specific protein).

183 Estrogen, progesterone, vitamin D and NO.Estrogen, progesterone, vitamin D and NO. –Usually, the intracellular receptor activated by a hormone is a transcription factor. Steroid hormones, thyroid hormones, and some local regulators enter target cells and bind to intracellular receptors Ecdysone ().Ecdysone ( insect molting hormone ). –A steroid hormone triggers the special cells to secrete new exoskeleton.

184 Different signal-transduction pathways in different cells can lead to different responses to the same signal.Different signal-transduction pathways in different cells can lead to different responses to the same signal.

185  Tropic hormones المنبه للغدد target other endocrine glands and are important to understanding chemical coordination. Humans have nine endocrine glands.Humans have nine endocrine glands. The Vertebrate Endocrine System Fig. 45.5, Page 960 الصنوبرية النخامية الدرقية الكظرية

186 The hypothalamus integrates endocrine and nervous function.The hypothalamus integrates endocrine and nervous function. –Neurosecretory cells of the hypothalamus produce hormones. a)Releasing hormones stimulate the anterior pituitary (adenohypophysis) to secrete hormones. b)Inhibiting hormones prevent the anterior pituitary from secreting hormones. The hypothalamus and pituitary integrate many functions of the vertebrate endocrine system 1)- Pituitary gland: secrets 9 hormonesthe anterior part and 2 hormones by the posterior part). 1)- Pituitary gland: secrets 9 hormones ( 7 hormones by the anterior part and 2 hormones by the posterior part).

187 A)- Anterior pituitary hormones. 1)Growth hormone (GH): a protein. Stimulates growth and metabolism.Stimulates growth and metabolism. Secretion regulated by hypothalamic hormones.Secretion regulated by hypothalamic hormones. Acts directly on tissues or acts via growth factors.Acts directly on tissues or acts via growth factors. Gigantism: العملقة excessive GH during development.Gigantism: العملقة excessive GH during development. Acromegaly : excessive GH production during adulthood.Acromegaly : excessive GH production during adulthood. Hypopituitary dwarfism القزمية : childhood GH deficiency.Hypopituitary dwarfism القزمية : childhood GH deficiency. 2)Prolactin (PRL): a protein. Stimulates milk production and secretion.Stimulates milk production and secretion. Secretion regulated by hypothalamic hormones.Secretion regulated by hypothalamic hormones. 3)Gonadotropins: glyocoproteins. Follicle-stimulating hormone (FSH).Follicle-stimulating hormone (FSH). –Stimulates production of sperm and ova. –Secretion regulated by hypothalamic hormones. Luteinizing hormone (LH) المُحفز لتكوين الجسم الأصفر.Luteinizing hormone (LH) المُحفز لتكوين الجسم الأصفر. –Stimulates ovaries and testes. –Secretion regulated by hypothalamic hormones.

188 4)Thyroid-stimulating hormone (TSH): a glycoprotein. Stimulates thyroid gland.Stimulates thyroid gland. Secretion regulated by thyroxine in blood.Secretion regulated by thyroxine in blood. Secretion regulated by hypothalamic hormones.Secretion regulated by hypothalamic hormones. 5)Adrenocorticotropic hormone (ACTH): a peptide Stimulates adrenal cortex secretion of glucocorticoidsStimulates adrenal cortex secretion of glucocorticoids Secretion regulated by glucocorticoids and hypothalamic hormones.Secretion regulated by glucocorticoids and hypothalamic hormones. 6)Melanocyte-stimulating hormone (MSH): a peptide. May play a role in fat metabolism.May play a role in fat metabolism. 7)Endorphins: peptides. Inhibit pain perception.Inhibit pain perception. Effects mimicked by heroin and other opiate drugs.Effects mimicked by heroin and other opiate drugs.

189 The anterior pituitary gland hormones Also called gonadotropine hormones هرمونات المناسل Adrenocorticotropic Melanocyte- stimulating H.

190 B)- Posterior pituitary hormones. –Oxytocin: a peptide. Stimulates contraction of the uterus and mammary glands.Stimulates contraction of the uterus and mammary glands. Secretion regulated by the nervous system.Secretion regulated by the nervous system. –Antidiuretic hormone (ADH): مُضاد لإدرار البول a peptide. Promotes retention of water by the kidneys.Promotes retention of water by the kidneys. High level decreases urination and vice versa.High level decreases urination and vice versa. Secretion regulated by water/salt balance.Secretion regulated by water/salt balance. 2- Pineal gland: الغدة الصنوبرية is a small mass of tissue near the center of the mammalian brain and involved in biorhythms. –The pineal gland secretes the hormone, melatonin, an amine. Involved in biological rhythms associated with reproduction.Involved in biological rhythms associated with reproduction. Secretion regulated by light/dark cycles.Secretion regulated by light/dark cycles.

191  Posterior pituitary  Posterior pituitary (neurohypophysis) stores and secretes hormones produced by the hypothalamus. Antidiuretic H

192 Thyroid releasing H. Thyroid stimulating H. The thyroid gland of mammals consists of two lobes located on the ventral surface of the trachea. It contains 4 small Parathyroid glands. It plays role in maintaining normal blood pressure, heart rate digestion..etc.The thyroid gland of mammals consists of two lobes located on the ventral surface of the trachea. It contains 4 small Parathyroid glands. It plays role in maintaining normal blood pressure, heart rate digestion..etc. Thyroid glands secretes 3 hormones:Thyroid glands secretes 3 hormones: I.Tri-iodothyronine [ (T 3 ), 3 I atoms ]: amino acid derivative. II.Thyroxine [ (T 4 ), 4 I atoms ]: amino acid derivative. –Stimulates and maintain metabolic processes. –Secretion regulated by TSH hormones. 3. Thyroid gland: secrets hormones function in development, bioenergetics, and homeostasis 3. Thyroid gland: secrets hormones function in development, bioenergetics, and homeostasis ثبات البيئة الفسيولوﭽـية الداخلية

193 a)Hyperthyroidism: the excessive secretion of thyroid hormones causes: high body temperaturehigh body temperature sweatingsweating weight lossweight loss IrritabilityIrritability high blood pressure.high blood pressure. b)Hypothyroidism: an insufficient قليل amount of thyroid hormones because deficiency of I in human diet (causes Goiter).  Infants: cretinism.  Adults: weight gain, lethargy, cold intolerance.  Goiter تضخم الغدة : often associated with iodine deficiency نقص. III.Calcitonin: a peptide.  Lowers blood Ca 2+ levels.  Its secretion regulated by calcium in blood.

194 PTH is secreted by The four parathyroid glands which embedded in the surface of the thyroid gland. It functions as:PTH is secreted by The four parathyroid glands which embedded in the surface of the thyroid gland. It functions as: –Raises blood Ca 2+ levels. –Secretion regulated by calcium in the blood. –Causes osteoclasts فقد الكالسيوم to break down bone, releasing Ca 2+ into the blood. –Stimulates the kidneys to reabsorb تعيد إمتصاص Ca 2+. –Stimulates kidneys to convert vitamin D to its active form, which stimulate intestine to absorb Ca 2+. –PTH and calcitonin are antagonistic متضادين hormones. Thus PTH and calcitonin regulate blood calcium level (important role in homeostasis). Hypoparathyoidism (tetany): it is a lack of PTH which causes:Hypoparathyoidism (tetany): it is a lack of PTH which causes: –Ca 2+ levels in the blood drop. –Convulsive contractions of the skeletal muscles. Parathyroid gland: Parathyroid hormone (PTH): a peptide

195 Hormonal control of Ca 2+ homeostasis in mammals blood

196 The pancreas has both endocrine and exocrine functions.The pancreas has both endocrine and exocrine functions. –Exocrine function: secretion of bicarbonate ions and digestive enzymes. –Endocrine function: insulin and glucagon secreted by beta and alpha cells of islets of Langerhans جيوب لانجرانز. 1.Insulin: a protein secreted by beta cells. Lowers blood glucose levels.Lowers blood glucose levels. –Stimulates all body cells (except brain cells) to take up glucose. –Slows glycogenolysis يبطىء تحلل الجليكوجين (a source of glucose). –Inhibits gluconeogenesis يوقف تكوين الجلوكوز. Secretion regulated by glucose in blood ( negative feedback ).Secretion regulated by glucose in blood ( negative feedback ). –Hypoinsulinism: diabetes mellitus نقص الإنسولين. Hereditary factors عامل وراثى and play a role in its development.Hereditary factors عامل وراثى and play a role in its development. High blood sugar levels – sugar excreted in the urine.High blood sugar levels – sugar excreted in the urine. Symptoms: excessive urination كثرة التبول and excessive thirst العطش.Symptoms: excessive urination كثرة التبول and excessive thirst العطش. 5. Pancreas : Endocrine tissues of the pancreas secrete insulin and glucagon, antagonistic hormones that regulate blood glucose

197 a)Type I diabetes mellitus ( insulin-dependent diabetes ). Autoimmune disorder.Autoimmune disorder. Usually appears in childhood الطفولة.Usually appears in childhood الطفولة. Treatment: insulin injections.Treatment: insulin injections. b)Type II diabetes mellitus ( non-insulin-dependent diabetes ). Usually due to target cells having a decreased responsiveness to insulin قلة الإستجابة للإنسولين.Usually due to target cells having a decreased responsiveness to insulin قلة الإستجابة للإنسولين. Usually occurs after age 40 – risk increases with age.Usually occurs after age 40 – risk increases with age. Accounts for over 90% of diabetes cases.Accounts for over 90% of diabetes cases. 2.Glucagon: a protein secreted by alpha cells. Raises blood glucose levels.Raises blood glucose levels. –Stimulates glycogenolysis تحلل الجليكوجين in the liver and skeletal muscle to produce glucose. –Secretion regulated by glucose in blood (negative feedback).

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199 The adrenal glands are located adjacent to the kidneys.The adrenal glands are located adjacent to the kidneys. –The adrenal cortex القشرة is the outer portion. –The adrenal medulla is the inner portion. I- Adrenal medulla المركز. –Developmentally and functionally related to the nervous system. –It produces the following hormones (in response to stress): a)Epinephrine هرمون القلب a)Epinephrine (adrenaline هرمون القلب ). b)Norepinephrine b)Norepinephrine (noradrenaline). They are amino acid derivatives (synthesized from tyrosine) and function as: Raises blood glucose level and blood fatty acid level.Raises blood glucose level and blood fatty acid level. Increases heart rate and stroke volume and dilates bronchioles.Increases heart rate and stroke volume and dilates bronchioles. Shunts blood away from skin, digestive organs, and kidneys, and increases blood flow to heart, brain, and skeletal muscle.Shunts blood away from skin, digestive organs, and kidneys, and increases blood flow to heart, brain, and skeletal muscle. 6. The adrenal gland: adrenal medulla and adrenal cortex help the body manage stress

200 II- Adrenal cortex: reacts to stress. Secretion of corticosteroids (a family of steroid hormones) is regulated by the nervous system in response to stress for example:Secretion of corticosteroids (a family of steroid hormones) is regulated by the nervous system in response to stress for example: a)Glucocorticoids. Raises blood glucose level.Raises blood glucose level. Secretion regulated by ACTH ( Adrenocorticotropic hormone ).Secretion regulated by ACTH ( Adrenocorticotropic hormone ). Abnormally high doses are administered as medication to suppress the inflammation response.Abnormally high doses are administered as medication to suppress the inflammation response. b)Mineralocorticoids ( example: aldosterone, which affects salt and water balance ). Promotes re-absorption of Na + and excretion of K + in kidneys.Promotes re-absorption of Na + and excretion of K + in kidneys. Their secretion regulated by K + in blood.Their secretion regulated by K + in blood. –A third group of corticosteriods are Sex hormones. Androgens secreted by the adrenal cortex may account for the female sex drive.Androgens secreted by the adrenal cortex may account for the female sex drive. The adrenal cortex also secretes small amounts of estrogens and progesterone.The adrenal cortex also secretes small amounts of estrogens and progesterone.

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202 a)Testes hormones: –Testosterone: steroids. Supports sperm formation.Supports sperm formation. Promote development and maintenance of male sex characteristics.Promote development and maintenance of male sex characteristics. Secretion regulated by FSH and LH.Secretion regulated by FSH and LH. b)Ovaries hormones: 1)Estrogens: steroids. Stimulate uterine lining growth.Stimulate uterine lining growth. Promote development and maintenance of female sex characteristics.Promote development and maintenance of female sex characteristics. Secretion regulated by FSH and LH.Secretion regulated by FSH and LH. 2)Progesterone: steroids. Promotes uterine lining growth.Promotes uterine lining growth. Secretion regulated by FSH and LH.Secretion regulated by FSH and LH. 7. Tests and ovaries: Gonadal steroids regulate growth, development, reproductive cycles, and sexual behavior

203 8- Thymus gland: It stimulates T lymphocytes Secretes Thymosin: a peptide. It stimulates T lymphocytes. Protein hormones affect target cells via receptors on the membrane protein Steroid hormones inter the target cells and trigger protein synthesis via receptors in the nucleus.

204

205

206 Section A: Gregor Mendel’s Discoveries MENDEL AND THE GENE IDEA MENDEL AND THE GENE IDEA

207 Mendel brought an experimental and quantitative approach to genetics Around 1857, Mendel began breeding garden peas to study inheritance وراثة. Because they are available in many varieties with distinct heritable مُتوارث characters صفات with different traits (genes).Around 1857, Mendel began breeding garden peas to study inheritance وراثة. Because they are available in many varieties with distinct heritable مُتوارث characters صفات with different traits (genes). Each pea plant has male (stamens) and female (carpal) sexual organs.Each pea plant has male (stamens) and female (carpal) sexual organs. In nature, pea plants typically self-fertilize, fertilizing ova with their own pollens.In nature, pea plants typically self-fertilize تلقيح ذاتى, fertilizing ova with their own pollens. However, Mendel could also move pollens from one plant to another to cross-pollinate يُـلقح plants.However, Mendel could also move pollens حبوب اللقاح from one plant to another to cross-pollinate يُـلقح plants.

208 In a breeding experiment, Mendel would cross-pollinate تلقيح خلطى (hybridize هَجن ) two contrasting متباينين, true- breeding pea varieties أنواع.In a breeding experiment, Mendel would cross-pollinate تلقيح خلطى (hybridize هَجن ) two contrasting متباينين, true- breeding pea varieties أنواع. –The true-breeding parents are the P (Parental generation) and their hybrid offspring النسل المُهجن are the F 1 (1 st Filial generation). Mendel would then allow the F 1 ( 1 st Filial generation ) hybrids to self-pollinate to produce an F 2 generation.Mendel would then allow the F 1 ( 1 st Filial generation ) hybrids to self-pollinate to produce an F 2 generation. It was mainly Mendel’s quantitative analysis تحليل كمى of F 2 plants that revealed the two fundamental lows of heredity:It was mainly Mendel’s quantitative analysis تحليل كمى of F 2 plants that revealed the two fundamental lows of heredity: A)- The law of segregation. B)- The law of independent assortment. A)- The law of segregation. B)- The law of independent assortment.

209 The F 1 hybrids from a cross تلقيح between purple-flowered and white- flowered pea plants would have pale purple flowers.The F 1 hybrids from a cross تلقيح between purple-flowered and white- flowered pea plants would have pale purple flowers بنفسجى باهت. Instead, ولكن the F 1 hybrids all have purple flowers, just a purple like their parents.Instead, ولكن the F 1 hybrids all have purple flowers, just a purple like their parents. A)- Law of segregation: the two alleles for a character are isolated into separate gametes A)- Law of segregation: قانون الإنعزال)) the two alleles ﭽـينات for a character are isolated into separate gametes This cross produced a 3 purple to 1 white ratio of traits in the F 2 offspring,This cross produced a 3 purple to 1 white ratio of traits in the F 2 offspring, Mendel reasoned that the heritable factor for white flowers was present in the F 1 plants, but it did not affect flower color.Mendel reasoned that the heritable factor for white flowers was present in the F 1 plants, but it did not affect flower color. Thus, purple flower is a dominant color (صفة سائدة) and white flower is a recessive color(صفة مُتنحية).Thus, purple flower is a dominant color (صفة سائدة) and white flower is a recessive color(صفة مُتنحية).

210 Mendel found similar 3 to 1 ratios of two traits among F 2 offspring when he conducted crosses for six other characters, each represented by two different varieties صفتين مختلفتين.Mendel found similar 3 to 1 ratios of two traits among F 2 offspring when he conducted crosses for six other characters, each represented by two different varieties صفتين مختلفتين. For example, when Mendel crossed two true-breeding varieties, one of which produced round seeds بذور مُستديرة, the other of which produced wrinkled seeds بذور مُجَعدة, all the F 1 offspring had round seeds, but among the F 2 plants, 75% of the seeds were round and 25% were wrinkled ().For example, when Mendel crossed two true-breeding varieties, one of which produced round seeds بذور مُستديرة, the other of which produced wrinkled seeds بذور مُجَعدة, all the F 1 offspring had round seeds, but among the F 2 plants, 75% of the seeds were round and 25% were wrinkled ( see second low in the next lecture ).

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212 Mendel developed a hypothesis to explain these results that consisted of four related ideas.Mendel developed a hypothesis إفتراض to explain these results that consisted of four related ideas. 1. Alternative version of genes account 1. Alternative version of genes ( different alleles الـﭽينين المتقابلين ) account for variations in inherited characters. for variations in inherited characters. –Different alleles vary somewhat in the sequence of nucleotides at the specific locus of a gene. –Different alleles vary somewhat in the sequence of nucleotides at the specific locus موضع of a gene. 2. For each character, an organism inherits two alleles, one from each parent. 2. For each character, an organism inherits يرث two alleles, one from each parent. –These homologous loci مَوقِعُه على الكروموسوم may be differ –In the flower-color example, the F 1 plants inherited a purple-flower allele from one parent and a white-flower allele from the other.

213 3. If two alleles differ, then, the dominant allele is fully expressed in the organism’s appearance and the recessive allele has no effect on the organism’s appearance. on the organism’s appearance. 4. The two alleles for each character segregate (separate) ينفصل during gamete production. –This segregation of alleles because of the distribution of homologous chromosomes to different gametes in meiosis. –If an organism has identical allele for a particular character, then that allele exists as a single copy in all gametes. –If different alleles are present, then 50% of the gametes will receive one allele and 50% will receive the other. The separation of alleles into separate gametes is summarized as Mendel’s law of segregation.The separation of alleles into separate gametes is summarized as Mendel’s law of segregation.

214 Summary The two alleles (genes) for a character are separated (segregated) into separate gametes and aggregated again by fertilization. Mendelian inheritance reflects rules of probability for the behaviour of genes. alleles For each character, an organism inherit two alleles (one from each parent). Dominant Recessive If the two alleles differ, one of them will be Dominant, and the other is Recessive. Red colour gene ( allele ) allele White colour gene ( allele ) Homologous chromosomes

215 A Punnett square analysis of the flower-color example demonstrates Mendel’s model.A Punnett square analysis of the flower-color example demonstrates Mendel’s model. Mendel’s model accounts for the 3:1 ratio in the F 2 generationMendel’s model accounts for the 3:1 ratio in the F 2 generation Mendel’s law of segregation accounts for the 3:1 ratio in the F 2 generation.Mendel’s law of segregation accounts for the 3:1 ratio in the F 2 generation. The F 1 hybrids will produce two classes of gametes, half with the purple-flower allele and half with the white-flower allele.The F 1 hybrids will produce two classes of gametes, half with the purple-flower allele and half with the white-flower allele. During self-pollination, the gametes of these two classes unite randomly.During self-pollination, the gametes of these two classes unite randomly. This can produce four equally likely combinations of sperm and ovum.This can produce four equally likely combinations of sperm and ovum. A Punnett square predicts the results of a genetic cross between individuals of known genotype الطرز الـﭽينى.A Punnett square predicts the results of a genetic cross between individuals of known genotype الطرز الـﭽينى.

216 PpPpPpPp PpPpPpPp P p P p PPPP PpPpPpPp PpPpPpPp PpPpPpPp PpPpPpPp pp PP p p 100% Purple F 2 generation 3 Purple : 1 White F 1 generation Recessive allele Dominant allele PPPP pp X PpPpPpPp PpPpPpPp PpPpPpPp PpPpPpPpX Pea plant Homozygous Heterozygous

217 Genotype (Genetic make up) PPPhenotype(Colour) PPPPpppp Homozygous PpPpPpPp PpPpPpPp Heterozygous An organism having a pair of identical alleles An organism having a pair of two different alleles Phenotype: Is t he organism’s appearance المظهر. Genotype: Is t he organism’s genetic makeup الطرز الـﭽينى.

218 Dominant character (allele)Dominant character (allele) الصفة السائدة Is fully expressed in the organism’s appearance. Is fully expressed in the organism’s appearance. Recessive character (allele)Recessive character (allele) الصفة المُتنحية Has no noticeable effect تأثير غير ملحوظ on the organism’s appearance. Has no noticeable effect تأثير غير ملحوظ on the organism’s appearance. Homozygous مُتماثل الجيناتHomozygous مُتماثل الجينات An organism with two identical alleles for a character. An organism with two identical alleles for a character. Heterozygous مُختلف الجيناتHeterozygous مُختلف الجينات An organism with two different alleles for a character. An organism with two different alleles for a character. Karyotype الطرز الكروموسومىKaryotype الطرز الكروموسومى The display of an organism’s chromosomal pattern Phenotype الطرز المظهرىPhenotype الطرز المظهرى A description of an organism’s traits (feature مظهر). A description of an organism’s traits (feature مظهر). Genotype الطرز الجينىGenotype الطرز الجينى A description of an organism’s genetic makeup. A description of an organism’s genetic makeup.

219 For flower color in peas, both PP and Pp plants have the same phenotype (purple) but different genotypes (homozygous and heterozygous).For flower color in peas, both PP and Pp plants have the same phenotype (purple) but different genotypes (homozygous and heterozygous). The only way to produce a white phenotype is to be homozygous recessive ( pp ) for the flower- color gene.The only way to produce a white phenotype is to be homozygous recessive ( pp ) for the flower- color gene.

220 It is not possible to predict the genotype of an organism with a dominant phenotype.It is not possible to predict the genotype of an organism with a dominant phenotype. –The organism must have one dominant allele, but it could be homozygous dominant or heterozygous. A test cross, breeding a homozygous recessive with dominant phenotype, but unknown genotype, can determine the identity of the unknown allele.A test cross, breeding a homozygous recessive with dominant phenotype, but unknown genotype, can determine the identity of the unknown allele. Q: What is the result of Cross hybridization of purple X white colored flowers ?

221 Section C: Mendelian Inheritance in Humans MENDEL AND THE GENE IDEA MENDEL AND THE GENE IDEA

222 Mendel’s experiments that followed the inheritance of flower color or other characters focused on only a single character via monohybrid crosses التزاوج أحادى الصفة.Mendel’s experiments that followed the inheritance of flower color or other characters focused on only a single character via monohybrid crosses التزاوج أحادى الصفة. He conduced other experiments in which he followed the inheritance of two different characters (a dihybrid cross التزاوج ثنائى الصفة).He conduced other experiments in which he followed the inheritance of two different characters (a dihybrid cross التزاوج ثنائى الصفة). In one dihybrid cross experiment, Mendel studied the inheritance of seed color and seed shape.In one dihybrid cross experiment, Mendel studied the inheritance of seed color and seed shape. –The allele for yellow seeds ( Y ) is dominant to the allele for green seeds ( y ). –The allele for round seeds ( R ) is dominant to the allele for wrinkled seeds ( r ) Mendel crossed true-breeding plants that had yellow & round seeds ( YYRR ) with true-breeding plants that has green & wrinkled seeds ( yyrr ).Mendel crossed true-breeding plants that had yellow & round seeds ( YYRR ) with true-breeding plants that has green & wrinkled seeds ( yyrr ). 2- The law of Independent Assortment: التوزيع الحر للـﭽـينات each pair of alleles segregates into gametes independently

223 The two pairs of alleles segregate independently of each other.The two pairs of alleles segregate independently of each other. –The presence of one specific allele for one trait has no impact تأثير on the presence of a specific allele for the second trait. When sperm and ova each with four classes of alleles combine, there would be 16 equally probable ways in which the alleles can combine in the F 2 generation.When sperm and ova each with four classes of alleles combine, there would be 16 equally probable ways in which the alleles can combine in the F 2 generation. These combinations produce four distinct phenotypes in a 9:3:3:1 ratio.These combinations produce four distinct phenotypes in a 9:3:3:1 ratio. This was consistent with Mendel’s results.This was consistent with Mendel’s results. Each character appeared to be inherited independently.Each character appeared to be inherited independently.

224 Mendel’s low of Independent ( Dihybrid cross ) It is a mating between two parent plants differing in two characters. Y R y r YR yr RY y r F 1 Yellow Round YYRR rryyX

225 R Y y r X R Y y r yyrr yyRR YYrr YYRRYR YrYrYrYr yRyRyRyR yrYR YrYrYrYr yRyRyRyR yr Yellow Round Yellow Wrinkled Green Round Green Wrinkled F 2: % of Phenotype ?

226 Thousands of genetic disorders, including disabling الإعاقة or deadly hereditary diseases, are inherited as simple recessive traits.Thousands of genetic disorders أمراض وراثية, including disabling الإعاقة or deadly hereditary diseases الأمراض الوراثية المُميتة, are inherited as simple recessive traits صفات وراثية مُتنحية. These range from the relatively mild (albinism ) to life-threatening (cystic fibrosis).These range from the relatively mild (albinism الألبينو، البُهاق ) to life-threatening (cystic fibrosis). Heterozygotes have a normal phenotype because one “normal” allele produces enough of the required factors ().Heterozygotes have a normal phenotype because one “normal” allele produces enough of the required factors (for normal trait). A recessively inherited disorder shows up only in the individuals who inherit homozygous recessive allele from parents.A recessively inherited disorder shows up يظهر only in the individuals who inherit homozygous recessive allele from parents. Thus, individuals who lack the disorder are either homozgyous dominant or heterozygous.Thus, individuals who lack the disorder are either homozgyous dominant or heterozygous. Heterozygous member may have no clear phenotypic effects, but is a carrier who may transmit a recessive allele to their offspring.Heterozygous member may have no clear phenotypic effects, but is a carrier who may transmit a recessive allele to their offspring. Most people with recessive disorders are born from carrier parents with normal phenotypes.Most people with recessive disorders are born from carrier parents with normal phenotypes. –Two carriers have a 1/4 chance of having a child with the disorder, 1/2 chance of a carrier, and 1/4 free. Many human disorders follow Mendelian patterns of inheritance Many human disorders أمراض follow Mendelian patterns of inheritance

227 1.Cystic fibrosis: a lethal recessive disorder –One in 25 person is a carrier. –The normal allele codes for a membrane protein that transports Cl - between cells and the environment. –If these channels are absent, there are abnormally high extracellular levels of chloride that causes the mucus coats of certain cells to become thicker and stickier than normal. –If these channels are absent, there are abnormally high extracellular levels of chloride that causes the mucus coats of certain cells to become thicker سميكة and stickier لزجة than normal. –This mucus build-up in the pancreas, lungs, digestive tract, and elsewhere favors bacterial infections. –Without treatment, affected children die before five, but with treatment can live past their late 20’s. 2.Tay-Sachs disease a lethal recessive disorder. –It is caused by a dysfunctional enzyme إنزيم غير عامل that fails to break down specific brain lipids. –The symptoms begin with seizures حول, blindness, and degeneration of motor and mental performance a few months after birth. –Inevitably, the child dies after a few years. A- Recessively inherited disorders الصفات المرضية المتنحية

228 3.Sickle-cell disease. 3.Sickle-cell disease خلايا الدم الهلالية. –It is caused by the substitution of a single amino acid in hemoglobin. –When oxygen levels in the blood of an affected individual are low, sickle-cell hemoglobin crystallizes into long rods. –This deforms red blood cells into a sickle shape. –Doctors can use regular blood transfusions to prevent brain damage and new drugs to prevent or treat other problems. The two alleles are codominant as both normal and abnormal hemoglobins are synthesized.The two alleles are codominant as both normal and abnormal hemoglobins are synthesized.

229 Normally it is relatively unlikely that two carriers of the same rare harmful allele will meet and mate.Normally it is relatively unlikely that two carriers of the same rare harmful allele will meet and mate. However, consanguineous mating, those between close relatives, increase the risk.However, consanguineous mating زواج الأقارب, those between close relatives, increase the risk. –These individuals who share a recent common ancestor are more likely to carry the same recessive alleles. Most societies and cultures have laws or taboos forbidding marriages between close relatives.Most societies and cultures have laws or taboos forbidding marriages between close relatives.

230 Although most harmful alleles are recessive, many human disorders are due to dominant alleles.Although most harmful alleles are recessive, many human disorders are due to dominant alleles. 1.Achondroplasia, a form of dwarfism, has an incidence of one case in 10,000 people. 1.Achondroplasia, a form of dwarfism القزمية, has an incidence of one case in 10,000 people. –Heterozygous individuals have the dwarf phenotype. –Those who are not achodroplastic dwarfs are homozygous recessive for this trait. Lethal dominant alleles are much less common than lethal recessives because if a lethal dominant kills an offspring before it can mature and reproduce, the allele will not be passed on to future generations.Lethal dominant alleles are much less common than lethal recessives because if a lethal dominant kills an offspring before it can mature and reproduce, the allele will not be passed on to future generations. B- Dominantly inherited disorders الصفات المرضية السائدة 2.Huntington’s disease: 2.Huntington’s disease: a degenerative ضُمور disease of the nervous system. The dominant lethal allele has no obvious phenotypic effect until an individuals is about 35 to 45 years old. The dominant lethal allele has no obvious phenotypic effect until an individuals is about 35 to 45 years old. –The deterioration of the nervous system is irreversible and inevitably fatal. –The deterioration of the nervous system is irreversible and inevitably fatal مُميت. Recently, molecular geneticists have used pedigree analysis of affected families to track down the Huntington’s allele to a locus near the tip of chromosomes 4.Recently, molecular geneticists have used pedigree analysis تحليل السجل العائلى of affected families to track down لنزع the Huntington’s allele to a locus near the tip of chromosomes 4.

231 Many other disorders have a multifactorial basis. Many other disorders have a multifactorial متعدد العوامل basis. –These have a genetic component plus a significant environmental influence. –Multifactorial disorders include heart disease, diabetes, cancer, alcoholism, and certain mental illnesses, such a schizophrenia and manic-depressive disorder. –The genetic component is typically polygenic. –The genetic component is typically polygenic متعدد الجينات. At present, little is understood about the genetic contribution to most multifactorial diseasesAt present, little is understood about the genetic contribution to most multifactorial diseases

232 Section B: Sex Chromosomes THE CHROMOSOMAL BASIS OF INHERITANCE 1.The chromosomal basis of sex varies with the organism 2.Sex-linked genes have unique patterns of inheritance

233 In human and other mammals, there are two varieties of sex chromosomes, X & Y.In human and other mammals, there are two varieties of sex chromosomes, X & Y. –An individual who inherits two X chromosomes usually develops as a female. –An individual who inherits an X and a Y chromosome usually develops as a male. 1. The chromosomal basis of sex varies with the organism This X-Y system of mammals is not the only chromosomal mechanism of determining sex.This X-Y system of mammals is not the only chromosomal mechanism of determining sex. Other options include the X-0 (in locust) system, the Z-W system (in birds), and the haplo-diploid system (in bees).Other options include the X-0 (in locust) system, the Z-W system (in birds), and the haplo-diploid system (in bees). In Human, the SRY gene (Sex-determining Region of the Y chromosome) modifies embryonic gonads into testes.In Human, the SRY gene (Sex-determining Region of the Y chromosome) modifies embryonic gonads into testes. Females lack the SRY gene, thus, the embryonic gonads develop into ovaries.Females lack the SRY gene, thus, the embryonic gonads develop into ovaries.

234 In the X-Y system, Y and X chromosomes behave as homologous chromosomes during meiosis.In the X-Y system, Y and X chromosomes behave as homologous chromosomes during meiosis. –In reality, they are only partially homologous and rarely undergo crossing over In both testes (XY) and ovaries (XX), the two sex chromosomes segregate during meiosis and each gamete receives one.In both testes (XY) and ovaries (XX), the two sex chromosomes segregate during meiosis and each gamete receives one. –Each egg receives an X chromosome. –Half the sperm receive an X chromosome and half receive a Y chromosome. Because of this, each conception has about a fifty-fifty chance of producing a particular sex.Because of this, each conception has about a fifty-fifty chance of producing a particular sex.

235 The sex chromosomes, especially the X chromosome, have genes for many characters unrelated to sex.The sex chromosomes, especially the X chromosome, have genes for many characters unrelated to sex. These sex-linked genes follow the same pattern of inheritance as the white-eye locus in Drosophila.These sex-linked genes جينات مرتبطة بالجنس follow the same pattern of inheritance as the white-eye locus in Drosophila. If a sex-linked trait is due to a recessive allele, a female have this phenotype only if homozygous.If a sex-linked trait is due to a recessive allele, a female have this phenotype only if homozygous. –Heterozygous females will be carriers. 2. Sex-linked genes have unique patterns of inheritance

236 Because males have only one X chromosome (hemizygous), any male receiving the recessive allele from his mother will express the trait.Because males have only one X chromosome (hemizygous), any male receiving the recessive allele from his mother will express the trait. Therefore, males are far more likely to inherit sex- linked recessive disorders than are females.Therefore, males are far more likely to inherit sex- linked recessive disorders مرض than are females. الصفات المرتبطة بالجنس تورث للأبناء الذكور من الأم فقط لأنهم يرثون منها الكروموسوم X الحامل لهذا النوع من الـﭼـينات، حيث إن Y لا يحمل شىء

237 Sex-linked disorders الأمراض المرتبطة بالجنس in human. 1.Duchenne muscular dystrophy: affects one in 3,500 males born in the United States. 1.Duchenne muscular dystrophy: وهن العضلات affects one in 3,500 males born in the United States. –Affected individuals rarely live past their early 20s. –This disorder is due to the absence of an X-linked gene for a key muscle protein, called dystrophin. –The disease is characterized by a weakening ضعف of the muscles and loss of coordination فـقـْد التوازن. 2.Hemophilia: is a sex-linked recessive trait defined by the absence of one or more clotting factors. 2.Hemophilia: النزيف الدموىis a sex-linked recessive trait defined by the absence of one or more clotting factors عوامل تجلط. –These proteins normally slow and then stop bleeding. –Individuals with hemophilia have prolonged bleeding because a firm clot forms slowly. –Individuals with hemophilia have prolonged bleeding نزيف مستمر because a firm clot تجلط forms slowly. –Individuals can be treated with intravenous injections of the missing protein. –This gene is transmitted to offspring via the mothers. –Thus, Sons borne from hemophilic woman should be exempted from circumcision. –Thus, Sons borne from hemophilic woman should be exempted يُستثنى from circumcision الختان.

238 3.Color blindness: is a disorder inherited as a recessive sex- linked character and affect both males and females. 3.Color blindness: عمى الألوان is a disorder inherited as a recessive sex- linked character and affect both males and females. –A color blind female () may be born to a color blind father () and a carrier mother () –A color blind female ( X a X a ) may be born to a color blind father ( X a Y ) and a carrier mother ( X A X a ) Although female mammals inherit two X chromosomes, only one X chromosome is active.Although female mammals الثدييات inherit two X chromosomes, only one X chromosome is active. Therefore, males and females have the same effective dose (one copy ) of genes on the X chromosome.Therefore, males and females have the same effective dose (one copy ) of genes on the X chromosome. –During female development, one X chromosome per cell condenses into a compact object, a Barr body جسم بار (in somatic cells). –This inactivates most of its genes. The condensed Barr body chromosome is reactivated in ovarian cells that produce ova.The condensed Barr body chromosome is reactivated in ovarian cells that produce ova.

239 It is common in meiosis and includes:It is common شائع in meiosis and includes: a)Chromosomal deletions/translocations a)Chromosomal deletions/translocations نقص أو فقد جزء  Homologous chromatids may break and rejoin at incorrect places, thus, one chromatid will loose more genes than it receives.  Homologous chromatids may break تـَنكسر and rejoin و تلتحم مرة أخرى at incorrect places, thus, one chromatid will loose more genes than it receives. b)Chromosomal duplications (Polyploidy ). b)Chromosomal duplications تضاعُف (Polyploidy تعدد الكروموسومات ).  result from nondisjunction during gamete production in one parent.  result from nondisjunction عدم الإنفصال الكامل للكروموسومات أثناء الإنقسام الميوزى during gamete production in one parent. A diploid embryo that is homozygous for a large deletion or male with a large deletion to its single X chromosome is usually missing many essential genes and this leads to a lethal outcome.A diploid embryo that is homozygous for a large deletion or male with a large deletion to its single X chromosome is usually missing يفتقد many essential genes and this leads to a lethal مُمِيت outcome. –Duplications and translocations are very harmful. –Duplications and translocations تغيير أماكن الأجزاء المقطوعة are very harmful. Translocation or inversion can alter phenotype because a gene’s expression is influenced by its location.Translocation or inversion can alter phenotype because a gene’s expression is influenced by its location. Chromosomal aberration. Chromosomal aberration الشذوذ الكروموسومى.

240 Several serious human disorders are due to these alterations of chromosome number and structure.Several serious human disorders are due to these alterations تغييرات of chromosome number and structure. Although the frequency of aneuploid zygotes may be quite high in humans, most of these alterations result in abortion long time before birth.Although the frequency يَحدُث مرارا of aneuploid zygotes اللاقحة الـمتعددة الكروموسومات may be quite high in humans, most of these alterations result in abortion إجهاض long time before birth قبل الولادة. –These developmental problems results from an imbalance among gene products. –These developmental problems results from an imbalance عدم توازن among gene products. Certain aneuploid conditions decrease the imbalance effect, leading to survival to birth.Certain aneuploid conditions decrease the imbalance effect, leading to survival to birth المولود. –But these individuals have a set of symptoms (syndromes) characteristic of the type of aneuploidy as following:- –But these individuals have a set of symptoms أعراض (syndromes) characteristic مُمَيـِزة of the type of aneuploidy as following:-

241 A)- Aneuploidy ( Chromosomal duplication) التعدد الكروموسومى غير التام, 1- Down syndrome [ : Is due to three copies of chromosome 21 ( Trisomies ). 1- Down syndrome [ Polyploidy (2n + 1 ), trisomy in autosomes]: Is due to three copies of chromosome 21 ( Trisomies مجموعات كروموسومية ثلاثية ). Although chromosome 21 is the smallest human chromosome, it severely alters an individual’s phenotype in specific ways. Although chromosome 21 is the smallest human chromosome, it severely alters يُغير an individual’s phenotype in specific ways.

242 Most cases of Down syndrome result from nondisjunction during gamete production in one parent.Most cases of Down syndrome result from nondisjunction عدم الإنفصال الكامل للكروموسومات أثناء الإنقسام الميوزى during gamete production in one parent. The frequency of Down syndrome correlates with the age of the mother.The frequency تِكرار of Down syndrome correlates with the age of the mother. –This may be linked to some age-dependent abnormality in the spindle checkpoint during meiosis I, leading to nondisjunction. 2- Klinefelter’s syndrome, (a)- An XXY male, occurs once in every 2000 live births. 2- Klinefelter’s syndrome [ Polyploidy (2n + 1), trisomy in sex chromosomes ], (a)- An XXY male, occurs once in every 2000 live births. These individuals have male sex organs, but are sterile.These individuals have male sex organs, but are sterile. There may be feminine characteristics, but their intelligence is normal.There may be feminine characteristics له صفات أنثوية, but their intelligence is normal. (b)- An XYY male, tend to somewhat taller than average. (b)- An XYY male, tend to somewhat taller than average. (c)- A trisomy female ( XXX ), which occurs once in every 2000 live births, produces healthy females. (c)- A trisomy female ( XXX ), which occurs once in every 2000 live births, produces healthy females. 3- Turner’s syndrome, a monosomy female ( X0 ), which occurs once in every 5000 births, produces phenotypic, but immature females غير ناضجة جنسيا.

243 B)- Chromosomal structure-alterations: It can also cause human disorders. It can also cause human disorders. Deletions, even in a heterozygous state, cause severe physical and mental problems.Deletions حزف, even in a heterozygous state, cause severe physical and mental problems. 1.Cri-du-chat, results from a specific deletion in chromosome 5. 1.Cri-du-chat عارض مواء القط, results from a specific deletion in chromosome 5. –These individuals are mentally retarded, have a small head with unusual facial features, and a cry like the mewing of a distressed cat. –This syndrome is fatal in infancy or early childhood. –This syndrome is fatal in infancy الطفوية or early childhood. 2.Myelogenous, [leukemia (CML)]. Caused by chromosomal translocations since a fragment of chromosome 22 switches places with a small fragment from the tip of chromosome 9.


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