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BIOZONE: p. 116-124 due WED 2/4 8.1 Intro to Cellular Respiration
Sponge: Set up Cornell Notes on pg. 71 Topic: 8.1 Intro to Cellular Respiration Essential Question: How is cellular respiration directly related to photosynthesis? 8.1 Intro to Cellular Respiration How is cellular respiration directly related to photosynthesis? Key Vocabulary: Catabolic pathway Anabolic pathway Oxidation Reduction Mitochondria Cellular Respiration BIOZONE: p due WED 2/4
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Chemical reactions carried out by an organism
Anabolic pathways: result in the synthesis of more complex molecules from simpler ones Photosynthesis Building a sugar molecule Catabolic pathways: result in the breakdown of complex molecules to smaller molecules Cellular respiration Breaking down sugar molecules
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Two general types of chemical reactions: Oxidation and reduction
Reduction: is the gain of electrons or a decrease in oxidation (reduce) state by a molecule, atom, or ion. Oxidation: is the loss of electrons or an increase in oxidation state by a molecule, atom, or ion. Tree map on P. 70
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Oxidation vs Reduction – Add to tree map
Loss of Electrons Gain of Electrons Gain of Oxygen Loss of Oxygen Loss of Hydrogen Gain in Hydrogen Results in many C-O (Carbon-oxygen) bonds Results in many C-H (carbon-hydrogen) bonds Results in a compound with LOWER potential energy Results in a compound with HIGHER potential energy
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Oxidation and reduction P.70
Loss of electrons Gain of electrons Gain of Oxygen Loss of Oxygen Loss of hydrogen Gain of hydrogen Results in many C-O (carbon-oxygen) bonds Results in many C-H (carbon-hydrogen) bonds Results in a compound with lower potential energy Results in a compound with higher energy These two reactions occur together during chemical reactions One compound’s or element’s loss is another compound or element’s gain Because they always occur together, they are considered redox reactions Plays a key role in the flow of energy through living systems
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Energy Energy is a topic of discussion every day in our modern world
IB students know what it is like to be tired and need a nap after a long day of school We talk about being hungry all the time Cellular respiration allows us to release the chemical energy stored in our food (glucose and other carbohydrates) to fuel all of our life processes.
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Cellular Respiration Organic molecules contain energy in their molecular structures Each covalent bond in glucose, amino acids or fatty acids represents stored chemical energy When we burn wood in a fire, we are releasing that stored chemical energy in the form of heat and light Burning is the release of chemical energy called rapid oxidation This is not controlled by enzymes and results in the breaking of many, many covalent bonds in a very short period of time and thus a nearly uncontrolled energy release
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Mitochondria It is inside the mitochondria and in the presence of oxygen that the majority of cellular respiration occurs
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Mitochondria Supply energy to the cell “POWER HOUSE” of the cell
Convert the molecules you eat into usable energy Rod shaped organelles that appear throughout the cytoplasm Their size is close to that of a bacterial cell Have their own DNA Contains ribosomes Double-membrane Outer membrane is smooth Inner membrane is folded into cristae Inside the inner membrane is a semi-fluid called matrix
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Bottom of P. 70 Mitochondria
Draw and label a diagram showing the structure of a mitochondrion as seen in electron micrographs Bottom of P. 70
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Mitochondria Draw and label a diagram showing the structure of a mitochondrion as seen in electron micrographs Outer Membrane Cristae (crista- singular) Matrix Inner Membrane
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Cellular Respiration Cellular Respiration: Cells break down (metabolize) their organic nutrients by way of slow oxidation (vs. rapid oxidation in the case of burning wood). The ultimate goal of releasing energy in a controlled way is to trap the released energy in the form of ATP molecules
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Cellular Respiration A molecule, such as glucose is acted on by a series of enzymes which catalyze a sequential series of reactions in which the covalent bonds are broken (oxidized) one at a time As each covalent bond is broken a small amount of energy is released If a cell does not have glucose available, other organics molecule may be substituted, such as fatty acids or amino acids
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Cellular Respiration Equation
All organisms need to produce ATP for energy, so all organisms carry out respiration
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Crash Course: Cellular Respiration (0-4m13s)
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Sponge: Set up Cornell Notes on pg. 73
Topic: 8.1 Cellular Respiration: Glycolysis & Krebs Cycle Essential Question: None 8.1 Cellular Respiration: Glycolysis & Krebs Cycle Key Vocabulary: Glycolysis Krebs Cycle BIOZONE: p due WED 2/4
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Glycolysis in a nutshell
All cells begin the process of cell respiration of glucose the same way. Glycolysis: Glucose enters a cell and floats in the cytoplasm Enzymes modify the glucose A series of reactions will split the 6-carbon glucose molecule into two 3- carbon molecules called pyruvate Energy from the breaking of these bonds was used to form a small amount of ATP of pyruvate
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Glycolysis Pyruvate Pyruvate c c c c c c 6-carbon glucose 2 ATP 2 ADP
Fructose-1, 6-biphosphate P P Glyceraldehyde-3-phosphate (G3P aka triose phosphate) 1 NAD+ 1 NAD+ 1 NADH 1 NADH P P P P 2 ADP 2ADP 2 ATP 2 ATP Pyruvate Pyruvate
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Glycolysis Glycolysis means "sugar splitting" It uses no oxygen
Occurs in the cytosol (cytoplasm) of the cell No required organelles Occurs both in aerobic (oxygen) and anaerobic (no oxygen) environments Occurs both in prokaryotic and eukaryotic cells
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Glycolysis: 1 Two molecules of ATP are used to begin glycolysis.
Phosphorylation: The phosphates from the ATPs attach to the glucose to form fructose-1, 6-biphosphate *Remember when ATP (adenosine triphosphate) loses a phosphate it becomes ADP (adenosine diphosphate)
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Glycolysis: 2 Lysis “to unbind”: The 6-carbon phosphorylated fructose is split into two 3-carbon sugars called glyceraldehyde-3-phosphate (G3P aka triose phosphate)
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Glycolysis: 3 Each G3P molecule undergoes oxidation to form a reduced molecule of NAD+ into NADH. As NADH is being formed, released energy is used to add an inorganic phosphate to the remaining 3- carbon compound
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Glycolysis: 3 Enzymes then remove the phosphate groups so they can be added to ADP to produce ATP The end result is the formation of: 4 ATP molecules 2 NADH molecules 2 Pyruvate molecules
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Krebs Cycle Once glycolysis has occurred and there is oxygen present, pyruvate enters the matrix of the mitochondria via active transport
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The Krebs Cycle The Link Reaction o CO² c c c (Occurs in Mitochondria)
Pyruvate CoA Acetyl CoA c c c NAD+ NADH c c c c c c c c c c Citrate 6c aka Citric acid The Link Reaction (occurs in mitochondria) Oxaloacetate o CO² c o NAD+ NADH NADH NAD+ c c c c c FADH₂ o CO² c o FAD NAD+ ATP NADH ADP + P i c c c c
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The Krebs cycle will run twice for each glucose molecule entering cellular respiration
Once for each pyruvate
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The Link Reaction Each pyruvate is decarboxylated when it loses a carbon dioxide molecule (released as a waste gas) The acetyl group is then oxidized with the formation of reduced NAD+ The acetyl group combines with coenzyme A and becomes known as acetyl-Coenzyme A (uh-C-tyl)
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1. Acetyl CoA combines with a 4-carbon compound called oxaloacetate (oxa-lo-ass-itate) The result is a 6-carbon compound known as citric acid
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2. Citrate (6-carbon compound) is oxidized (H+ lost) to form a 5-carbon compound Decarboxylation: Carbon is released from the cell as CO² While the 6-carbon compound is oxidized, NAD+ is reduced to form NADH (H+ added)
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3. The 5-carbon compound is oxidized (H+ lost) to form a 4-carbon compound Decarboxylation: another carbon is released from the cell as CO² Another NAD+ is reduced to form NADH (H+ added)
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4. The 4-carbon compound undergoes various changes resulting in several products: NAD reduced (H+) to NADH Coenzyme FAD reduced (H+) to form FADH₂ Phosphorylation: reduction of an ADP to form ATP
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5. The 4-carbon compound is changed during step 4 to re-form the starting compound of the cycle, oxaloacetate The oxaloacetate may then begin the cycle again!
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PRODUCTS OF THE KREBS CYCLE
2 ATP molecules 6 molecules of NADH (allow energy storage and transfer) 2 molecules of FADH₂ 4 molecules of carbon dioxide (released) ****REMEMBER: The cycle rotates twice!!!!!! So far, only 4 ATPs have been gained (6 generated, but it “costs” two to start glycolysis)
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Crash Course: Cellular Respiration (4m13s-11m3s)
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BIOZONE: p. 116-124 due TOMORROW
Sponge: Set up Cornell Notes on pg. 75 Topic: 8.1 Cellular Respiration: ETC Essential Question: Compare the ETC to the photosystems (II/I) in photosynthesis. 8.1 Cellular Respiration: ETC Compare the ETC to the photosystems (II/I) in photosynthesis. Key Vocabulary: Oxidative Phosphorylation BIOZONE: p due TOMORROW
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Oxidative Phosphorylation: ETC/ ATP synthase
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Oxidative Phosphorylation: ETC/ ATP synthase
The ETC is where most of the ATPs from glucose break down are produced It is the first stage of CR where O² is actually needed Occurs on the inner mitochondrial membrane and on the membrane of the cristae In this chain, electrons pass from one carrier to another because the receiving molecule has a higher electronegativity (therefore a stronger attraction) for electrons The source of the electrons are the coenzymes NADH and FADH₂ from the Krebs Cycle
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Oxidative Phosphorylation: ETC/ ATP synthase
Cyt∙c Q FMN Fe∙S
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Electron Transport Chain
Oxidative Phosphorylation 1. Proteins inside the inner membrane of the mitochondria take high energy electrons from NADH and FADH₂ NADH is oxidized to become NAD H e- Electrons enter the ETC into the FMN protein FADH₂ is oxidized to become: FAD H e- Electrons enter the ETC into the Fe∙S protein Electrons will continue on to the Q electron carrier (not a protein) which will take them to the next protein in the chain
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Electron Transport Chain
2. High energy electrons travel through the proteins in the ETC losing energy at each protein The proteins use energy from the electrons as they are de- energized to pump the hydrogen ions across the inner membrane to produce a chemiosmotic gradient The hydrogen ions build up on the inside of the inner membrane Inside of membrane
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Electron Transport Chain
3. Oxygen enters the cellular respiration process as the final electron acceptor in the ETC Water of metabolism: The O² picks up electrons and 2 H+ (from the aqueous surroundings of the matrix) to form water The H²O molecules are given off as a waste product
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ATP Synthase 4. Energy is now available as a result of the ETC
Chemiosmosis: H+ diffuse through the protein channel of the ATP synthase back into the matrix As H+ move through ATP synthase, the enzymes harness the available energy allowing the phosphorylation of ADP to ATP (adding of phosphates)
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Products of Oxidative Phosphorylation
32 ATP (approx.)
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Cellular Respiration Overview
The Reactants of Cellular Respiration Glucose (from Photosynthesis) O² 2 2 6 The Products of Cellular Respiration CO² H²O 36 ATP (approx.) 32 6 6
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Cellular Respiration Overview
Process ATP used ATP produced Net ATP gain Glycolysis 2 4 Krebs Cycle ETC/ chemiosmosis 32 TOTAL 38 36 2 2 6 32 6 6
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Cellular Respiration Overview
Theoretically 36 ATPs are produced by CR, but in reality the # is closer to 30 This is thought to be due to some H+ moving back to the matrix WITHOUT going through the ATP synthase The 30 ATPs generated by CR account for approx 30% of the energy present in the chemical bonds of glucose The remainder of the energy is lost from the cell as heat Process ATP used ATP produced Net ATP gain Glycolysis 2 4 Krebs Cycle ETC/ chemiosmosis 32 TOTAL 38 36
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The products of cellular respiration are the reactants of photosynthesis
The reactants of cellular respiration are the products of photosynthesis
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Crash Course: Cellular Respiration (11m-13m25s)
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8.1 Other Aspects of Cellular Respiration
Sponge: Set up Cornell Notes on pg. 77 Topic: 8.1 Other Aspects of Cellular Respiration Essential Question: 8.1 Other Aspects of Cellular Respiration Key Vocabulary: Electromagnetic spectrum Action spectrum
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Alcoholic Fermentation
P. 76 Lactic Acid Fermentation
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The mitochondria and cellular respiration
In biology, the relationship between structure and function is a universal theme Chloroplast Structure Function Allowed Separates the contents of the mitochondrion from the rest of the cell Outer mitochondrial membrane Internal semi-fluid that contains the enzymes for the link reaction in the Krebs cycle Matrix Increase surface area for oxidative phosphorylation (ETC/ATP synthase) Cristae Inner mitochondrial membrane Contains the protein carriers for the ETC and ATP synthase for chemiosmosis Reservoir for hydrogen ions (protons), the high concentration of hydrogen ions is necessary for chemiosmosis Space between inner and outer membranes
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Anaerobic Respiration
All pathways of cellular respiration start with glycolysis If an organism derives their ATP completely without the use of oxygen they are referred to as anaerobic This is known as fermentation Draw a small picture on p. 77
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Anaerobic Respiration
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Fermentation There are two main anaerobic pathways:
Alcoholic fermentation Lactic acid fermentation
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Alcoholic Fermentation
Glycolysis occurs first (net gain 2 ATP- 2 pyruvate) Yeast will convert both the 3-carbon pyruvates into molecules of ethanol Ethanol is a 2-carbon molecule, so a carbon atom is “lost” in this conversion The “lost” carbon atom is given off as a CO² molecule Both ethanol and CO² that are produces are waste products to the yeast and are simply given off to the environment
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Alcoholic Fermentation
Draw on top of p. 76 Ethanol glycolysis Ethanol
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Ex: Yeast is added to baker’s bread as the generation of CO² molecules helps the dough rise It is also common to use yeast in the production of ethanol as drinking alcohol
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Alcoholic Fermentation
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Lactic Acid Fermentation
Organisms that use an aerobic cell respiration pathway sometimes find themselves in a metabolic situation where they cannot supply enough oxygen to their cells
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Lactic Acid Fermentation
Ex: A person pushing beyond their normal exercise pattern or routine In this situation, the person’s pulmonary and cardiovascular systems (lungs and heart) supply as much oxygen to their cells as is physically possible If a person’s exercise exceeds their capacity of supplying oxygen, then at least some of the glucose entering into cellular respiration will follow the anaerobic pathways called lactic acid fermentation
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Lactic Acid Fermentation
Glycolysis first (net gain 2 ATP- 2 pyruvate) In a low-oxygen situation excess pyruvate molecules are converted into lactic acid molecules Lactic acid molecules are 3-carbon molecules (so there is no production of CO²)
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Lactic Acid Fermentation
What benefit then? It allows glycolysis to continue with the small gain of ATP generated in addition to the ATP which is already being generated through the aerobic pathway
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Lactic Acid Fermentation
Draw on bottom of p. 76 Lactate glycolysis Reaction reversible with O² present Lactate
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Lactic acid fermentation is used in food production using bacteria:
yogurt cheese Turns soy beans into soy sauce Turns cabbage into sauerkraut
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Aerobic Cell Respiration is the most Efficient!!!
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