Chapter 07 Lecture and Animation Outline See separate PowerPoint slides for all figures and tables pre-inserted into PowerPoint without notes and animations. To run the animations you must be in Slideshow View. Use the buttons on the animation to play, pause, and turn audio/text on or off. Please Note: Once you have used any of the animation functions (such as Play or Pause), you must first click on the slides background before you can advance to the next slide. 7.1 Learning Objectives Review energy transformations important for life Define autotrophs & heterotrophs Understand role of redox reactions & electron carriers in energy metabolism. Define respiration vs. fermentation Discuss the 2 ways ATP is made 2 Energy Transformations 3 cell respiration photosynthesis C 6 H 12 O 6 O 2 H 2 O CO 2 Energy in Our Food 4 How Organisms Obtain Energy Autotrophs Produce their own organic molecules through photosynthesis Heterotrophs Eat organic compounds produced by other organisms 5mons/3/3f/Ferns02.jpg 6 Cellular (Aerobic) respiration C 6 H 12 O 6 + 6O 2 6CO 2 + 6H 2 O G = 686 kcal/mol of glucose This large amount of energy must be released in small steps rather than all at once, but how 7 Cellular Respiration Cellular respiration is a series of redox reactions Oxidation loss of electrons (LEO) Reduction gain of electron (GER) Dehydrogenation lost electrons are accompanied by protons A hydrogen atom is lost (1 electron, 1 proton) To follow the e -, follow the Hs!!!!!!!! 8 Redox- The Electron Carriers During redox reactions, electrons carry energy from one molecule to another Electron Carriers in Cell Respiration are Nicotinamide adenosine dinucleotide (NAD + ) Reduced form = NADH (2 e -, 2 H + ) Flavin adenine dinucleotide (FAD) Reduced form = FADH 2 (2 e -, 2H + ) 9 Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. HH O NH 2 + 2H CH 2 O O O H H NH 2 H H N N N CH 2 O O O H H NH 2 OO H H N N N HH O N N HH H C C OP OPOO OP OO OP N N OH CH 2 NADH: Reduced form of nicotinamide O O O O NAD + : Oxidized form of nicotinamide Reduction Oxidation Adenine OH NH 2 + H + CH 2 OO 10 Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Product Enzyme NAD + NAD 2e H+H+ +H + Energy-rich molecule NAD + 1. Enzymes that use NAD + as a coenzyme for oxidation reactions bind NAD + and the substrate. 2. In an oxidationreduction reaction, 2 electrons and a proton are transferred to NAD +, forming NADH. A second proton is donated to the solution. 3. NADH diffuses away and can then donate electrons to other molecules. Reduction Oxidation H H H H H H H H 11 2e Electrons from food High energy Low energy 2H + 1 / 2 O2O2 Energy released for ATP synthesis H2OH2O Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Respiration vs. Fermentation Aerobic respiration Final electron receptor is oxygen (O 2 ) Anaerobic respiration Final electron acceptor is an inorganic molecule (not O 2 ) Fermentation Final electron acceptor is an organic molecule, converted into lactic acid or ethanol + CO 2 12 13 ATP Cells use ATP to drive endergonic reactions G (free energy) = 7.3 kcal/mol 2 mechanisms for synthesis 1. Substrate-level phosphorylation Transfer phosphate group directly to ADP During glycolysis & Krebs (Citric Acid) Cycle 2. Oxidative phosphorylation ATP synthase uses energy from a proton gradient During ETC and Chemiosmosis Substrate-level Phosphorylation 14 PEP ADP Enzyme ATP Adenosine Pyruvate P P P P P P P P P P Adenosine P P Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Question 1 Which of the following processes uses an inorganic molecule besides oxygen as a terminal electron acceptor? a.Aerobic respiration b.Fermentation c.Anaerobic respiration d.All of the above 7.2 Learning Objectives Describe the process of glycolysis. Where does it take place in the cell What goes in, what comes out Why is ATP required to start glycolysis Is O 2 required for glycolysis Calculate the energy yield from glycolysis. 16 17 Oxidation of Glucose The complete oxidation of glucose proceeds in stages: 1. Glycolysis 2. Pyruvate oxidation 3. Krebs cycle 4. Electron transport chain & chemiosmosis 18 Outer mitochondrial membrane Intermembrane space Inner mitochondrial membrane Electron Transport Chain Chemiosmosis Glycolysis Glucose Pyruvate Oxidation Krebs Cycle Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 19 Outer mitochondrial membrane Intermembrane space Mitochondrial matrix FAD O2O2 Inner mitochondrial membrane Electron Transport Chain Chemiosmosis ATP Synthase NAD + Glycolysis Pyruvate Glucose Pyruvate Oxidation Acetyl-CoA Krebs Cycle CO 2 ATP H2OH2O ee ee NADH CO 2 ATP NADH FADH 2 Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. H+H+ ee 20 Glycolysis Converts 1 glucose (6 carbons) to 2 pyruvate (3 carbons) 10-step biochemical pathway Occurs in the cytoplasm Net production of 2 ATP molecules by substrate-level phosphorylation 2 NADH produced by the reduction of NAD + Only process that occurs in red blood cells since they do not have mitochondria! Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Glycolysis NADH Pyruvate Oxidation ATP Electron Transport Chain Chemiosmosis Krebs Cycle Fig Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Glycolysis NADH Pyruvate Oxidation ATP Electron Transport Chain Chemiosmosis Krebs Cycle 6-carbon sugar diphosphate Priming Reactions PP ATP ADP 6-carbon glucose (Starting material) Glycolysis begins with the addition of energy. Two high- energy phosphates (P) from two molecules of ATP are added to the 6-carbon molecule glucose, producing a 6-carbon molecule with two phosphates. Fig Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Glycolysis NADH Pyruvate Oxidation ATP Electron Transport Chain Chemiosmosis Krebs Cycle 6-carbon sugar diphosphate Priming Reactions Cleavage PP P P ATP ADP 3-carbon sugar phosphate 3-carbon sugar phosphate 6-carbon glucose (Starting material) Glycolysis begins with the addition of energy. Two high- energy phosphates (P) from two molecules of ATP are added to the 6-carbon molecule glucose, producing a 6-carbon molecule with two phosphates. Then, the 6-carbon molecule with two phosphates is split in two, forming two 3-carbon sugar phosphates. Fig. 7.6 Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Glycolysis NADH Pyruvate Oxidation ATP Electron Transport Chain Chemiosmosis Krebs Cycle 6-carbon sugar diphosphate NAD + Priming Reactions Cleavage Oxidation and ATP Formation NADH PP P P ATP ADP 3-carbon sugar phosphate 3-carbon sugar phosphate PiPi PiPi ADP ATP ADP ATP 3-carbon pyruvate 3-carbon pyruvate 6-carbon glucose (Starting material) Glycolysis begins with the addition of energy. Two high- energy phosphates (P) from two molecules of ATP are added to the 6-carbon molecule glucose, producing a 6-carbon molecule with two phosphates. Then, the 6-carbon molecule with two phosphates is split in two, forming two 3-carbon sugar phosphates. An additional Inorganic phosphate ( P i ) is incorporated into each 3-carbon sugar phosphate. An oxidation reaction converts the two sugar phosphates into intermediates that can transfer a phosphate to ADP to form ATP. The oxidation reactions also yield NADH giving a net energy yield of 2 ATP and 2 NADH. Fig Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Glucose Hexokinase Glucose 6-phosphate Glucose Glycolysis: The Reactions Glycolysis NADH Pyruvate Oxidation ATP ADP Electron Transport Chain Chemiosmosis Krebs Cycle ATP Glucose 6-phosphate CH 2 OH O CH 2 O O P 1 Fig Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Glucose Hexokinase Glucose 6-phosphate Glucose Glycolysis: The Reactions Glycolysis NADH Pyruvate Oxidation ATP ADP Electron Transport Chain Chemiosmosis Krebs Cycle ATP 1. Phosphorylation of glucose by ATP. Glucose 6-phosphate CH 2 OH O CH 2 O O P 1 Fig Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Glucose Hexokinase Phosphofructokinase Glucose 6-phosphate Fructose 6-phosphate Fructose 1,6-bisphosphate Isomerase Aldolase ADP Glucose Glycolysis: The Reactions Glycolysis NADH Pyruvate Oxidation ATP ADP Electron Transport Chain Chemiosmosis Krebs Cycle ATP Phosphoglucose isomerase Glyceraldehyde 3- phosphate (G3P) Dihydroxyacetone phosphate 1. Phosphorylation of glucose by ATP. 23. Rearrangement, followed by a second ATP phosphorylation. Glucose 6-phosphate Fructose 6-phosphate Fructose 1,6-bisphosphate CH 2 OH O CH 2 O O P O O P CH 2 OH OCH 2 O O PP Fig Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Glucose Hexokinase Phosphofructokinase Glucose 6-phosphate Fructose 6-phosphate Fructose 1,6-bisphosphate Isomerase Aldolase ADP Glucose Glyceraldehyde 3-phosphate Glycolysis: The Reactions Glycolysis NADH Pyruvate Oxidation ATP ADP Electron Transport Chain Chemiosmosis Krebs Cycle ATP Phosphoglucose isomerase Glyceraldehyde 3- phosphate (G3P) Dihydroxyacetone phosphate 1. Phosphorylation of glucose by ATP. 23. Rearrangement, followed by a second ATP phosphorylation. 45. The 6-carbon molecule is split into two 3-carbon moleculesone G3P, another that is converted into G3P in another reaction. Glucose 6-phosphate Fructose 6-phosphate Fructose 1,6-bisphosphate Dihydroxyacetone Phosphate CH 2 OH O CH 2 O O P O O P CH 2 OH OCH 2 O O PP CHOH H CO CH 2 O P CO O P CH 2 OH Fig Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. NADH NAD+ NADH PiPi NAD+ Glucose Hexokinase Phosphofructokinase Glucose 6-phosphate Fructose 6-phosphate Fructose 1,6-bisphosphate Isomerase Aldolase ADP Glucose Glyceraldehyde 3-phosphate Glycolysis: The Reactions Glycolysis NADH Pyruvate Oxidation ATP ADP Electron Transport Chain Chemiosmosis Krebs Cycle ATP Phosphoglucose isomerase Glyceraldehyde 3- phosphate (G3P) Dihydroxyacetone phosphate 1. Phosphorylation of glucose by ATP. 23. Rearrangement, followed by a second ATP phosphorylation. 45. The 6-carbon molecule is split into two 3-carbon moleculesone G3P, another that is converted into G3P in another reaction. 6. Oxidation followed by phosphorylation produces two NADH molecules and two molecules of BPG, each with one high-energy phosphate bond. 1,3-Bisphosphoglycerate (BPG) 1,3-Bisphosphoglycerate (BPG) Glyceraldehyde 3-phosphate dehydrogenase PiPi 1,3-Bisphospho- glycerate Glucose 6-phosphate Fructose 6-phosphate Fructose 1,6-bisphosphate Dihydroxyacetone Phosphate CH 2 OH O CH 2 O O P O O P CH 2 OH OCH 2 O O PP CHOH H CO CH 2 O P CO O P CH 2 OH CHOH OCO CH 2 O P P Fig Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. NADH NAD+ NADH PiPi NAD+ Glucose Hexokinase Phosphofructokinase Glucose 6-phosphate Fructose 6-phosphate Fructose 1,6-bisphosphate Isomerase Aldolase ADP Glucose Glyceraldehyde 3-phosphate Glycolysis: The Reactions Glycolysis NADH Pyruvate Oxidation ATP ADP Electron Transport Chain Chemiosmosis Krebs Cycle ATP Phosphoglucose isomerase Glyceraldehyde 3- phosphate (G3P) Dihydroxyacetone phosphate 1. Phosphorylation of glucose by ATP. 23. Rearrangement, followed by a second ATP phosphorylation. 45. The 6-carbon molecule is split into two 3-carbon moleculesone G3P, another that is converted into G3P in another reaction. 6. Oxidation followed by phosphorylation produces two NADH molecules and two molecules of BPG, each with one high-energy phosphate bond. 7. Removal of high-energy phosphate by two ADP molecules produces two ATP molecules and leaves two 3PG molecules. 1,3-Bisphosphoglycerate (BPG) 1,3-Bisphosphoglycerate (BPG) Glyceraldehyde 3-phosphate dehydrogenase PiPi ADP Phosphoglycerate kinase ADP ATP 3-Phosphoglycerate (3PG) 3-Phosphoglycerate (3PG) ATP 3-Phospho- glycerate 1,3-Bisphospho- glycerate Glucose 6-phosphate Fructose 6-phosphate Fructose 1,6-bisphosphate Dihydroxyacetone Phosphate CH 2 OH O CH 2 O O P O O P CH 2 OH OCH 2 O O PP CHOH H CO CH 2 O P CO O P CH 2 OH CHOH OCO CH 2 O P P CHOH OO CO CH 2 O P Fig Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. NADH NAD+ NADH PiPi NAD+ Glucose Hexokinase Phosphofructokinase Glucose 6-phosphate Fructose 6-phosphate Fructose 1,6-bisphosphate Isomerase Aldolase Enolase ADP Glucose Glyceraldehyde 3-phosphate Glycolysis: The Reactions Glycolysis NADH Pyruvate Oxidation H2OH2O ATP ADP Electron Transport Chain Chemiosmosis Krebs Cycle ATP Phosphoglucose isomerase Glyceraldehyde 3- phosphate (G3P) Dihydroxyacetone phosphate 1. Phosphorylation of glucose by ATP. 23. Rearrangement, followed by a second ATP phosphorylation. 45. The 6-carbon molecule is split into two 3-carbon moleculesone G3P, another that is converted into G3P in another reaction. 6. Oxidation followed by phosphorylation produces two NADH molecules and two molecules of BPG, each with one high-energy phosphate bond. 7. Removal of high-energy phosphate by two ADP molecules produces two ATP molecules and leaves two 3PG molecules. 89. Removal of water yields two PEP molecules, each with a high-energy phosphate bond. 1,3-Bisphosphoglycerate (BPG) 1,3-Bisphosphoglycerate (BPG) Glyceraldehyde 3-phosphate dehydrogenase PiPi ADP Phosphoglycerate kinase ADP ATP 3-Phosphoglycerate (3PG) 3-Phosphoglycerate (3PG) 2-Phosphoglycerate (2PG) 2-Phosphoglycerate (2PG) H2OH2O ATP Phosphoenolpyruvate (PEP) Phosphoenolpyruvate (PEP) Phosphoenol- pyruvate 3-Phospho- glycerate 1,3-Bisphospho- glycerate Glucose 6-phosphate Fructose 6-phosphate Fructose 1,6-bisphosphate Dihydroxyacetone Phosphate 2-Phospho- glycerate CH 2 OH O CH 2 O O P O O P CH 2 OH OCH 2 O O PP CHOH H CO CH 2 O P CO O P CH 2 OH CHOH OCO CH 2 O P P CHOH OO CO CH 2 O P H C O OO CO CH 2 OH P CO OO CO CH 2 P Phosphoglyceromutase Fig. 7.7 Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. NADH NAD+ NADH PiPi NAD+ Glucose Hexokinase Phosphofructokinase Glucose 6-phosphate Fructose 6-phosphate Fructose 1,6-bisphosphate Isomerase Aldolase Pyruvate Enolase Pyruvate kinase ADP 10 Glucose Glyceraldehyde 3-phosphate Pyruvate Glycolysis: The Reactions Glycolysis NADH Pyruvate Oxidation H2OH2O ATP ADP Electron Transport Chain Chemiosmosis Krebs Cycle ATP Phosphoglucose isomerase Glyceraldehyde 3- phosphate (G3P) Dihydroxyacetone phosphate 1. Phosphorylation of glucose by ATP. 23. Rearrangement, followed by a second ATP phosphorylation. 45. The 6-carbon molecule is split into two 3-carbon moleculesone G3P, another that is converted into G3P in another reaction. 6. Oxidation followed by phosphorylation produces two NADH molecules and two molecules of BPG, each with one high-energy phosphate bond. 7. Removal of high-energy phosphate by two ADP molecules produces two ATP molecules and leaves two 3PG molecules. 89. Removal of water yields two PEP molecules, each with a high-energy phosphate bond. 10. Removal of high-energy phosphate by two ADP molecules produces two ATP molecules and two pyruvate molecules. 1,3-Bisphosphoglycerate (BPG) 1,3-Bisphosphoglycerate (BPG) Glyceraldehyde 3-phosphate dehydrogenase PiPi ADP Phosphoglycerate kinase ADP ATP 3-Phosphoglycerate (3PG) 3-Phosphoglycerate (3PG) 2-Phosphoglycerate (2PG) 2-Phosphoglycerate (2PG) H2OH2O ATP Phosphoenolpyruvate (PEP) Phosphoenolpyruvate (PEP) ADP ATP Phosphoenol- pyruvate 3-Phospho- glycerate 1,3-Bisphospho- glycerate Glucose 6-phosphate Fructose 6-phosphate Fructose 1,6-bisphosphate Dihydroxyacetone Phosphate 2-Phospho- glycerate CH 2 OH O CH 2 O O P O O P CH 2 OH OCH 2 O O PP CHOH H CO CH 2 O P CO O P CH 2 OH CHOH OCO CH 2 O P P CHOH OO CO CH 2 O P H C O OO CO CH 2 OH P CO OO CO CH 2 P CO OO CO CH Phosphoglyceromutase 33 Please note that due to differing operating systems, some animations will not appear until the presentation is viewed in Presentation Mode (Slide Show view). You may see blank slides in the Normal or Slide Sorter views. All animations will appear after viewing in Presentation Mode and playing each animation. Most animations will require the latest version of the Flash Player, which is available at 34 NADH must be recycled For glycolysis to continue, NADH must be recycled to NAD + by either: 1. Aerobic respiration Oxygen is available as the final electron acceptor Produces significant amount of ATP 2. Fermentation Occurs when oxygen is not available Organic molecule is the final electron acceptor 35 Fate of pyruvate Depends on oxygen availability. When oxygen is present, pyruvate is oxidized to acetyl-CoA which enters the Krebs cycle Aerobic respiration Without oxygen, pyruvate is reduced in order to oxidize NADH back to NAD + Fermentation 36 Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Without oxygen NAD + O2O2 NADH ETC in mitochondria Acetyl-CoA Ethanol NAD + CO 2 NAD + H2OH2O Lactate Pyruvate Acetaldehyde NADH With oxygen Krebs Cycle Outer mitochondrial membrane Intermembrane space Glycolysis Pyruvate Glucose ATP Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. NADH Question 4 Glycolysis costs ____ ATPs, but makes ___ ATPs; thus it has a net yield of ___ ATPs. a.3, 6, 3 b.2, 4, 2 c.2, 2, 0 d.0, 2, 2 e.4, 8, 4 Question 6 All of the glycolysis reactions do not require oxygen and can take place in an anaerobic environment. a.This is true b.This is false Learning Objectives For both pyruvate oxidation and the Krebs cycle Where does it take place in the cell What goes in, what comes out What is energy yield 40 41 Pyruvate Oxidation In the presence of oxygen, pyruvate is oxidized Occurs in the mitochondria in eukaryotes Occurs at the plasma membrane in prokaryotes Outer mitochondrial membrane Intermembrane space Mitochondrial matrix Glycolysis Pyruvate Glucose Pyruvate Oxidation Acetyl-CoA ATP Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. NADH 43 For each 3-carbon pyruvate molecule: 1 CO 2 Decarboxylation by pyruvate dehydrogenase 1 NADH 1 acetyl-CoA which consists of 2 carbons from pyruvate attached to coenzyme A Acetyl-CoA proceeds to the Krebs cycle Products of pyruvate oxidation 44 Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Glycolysis Pyruvate Oxidation NADH Krebs Cycle Electron Transport Chain Chemiosmosis Pyruvate Oxidation: The Reaction NAD + CO 2 CoA Acetyl Coenzyme A Pyruvate Acetyl Coenzyme A O CH 3 C OO C O S CoA CH 3 OC NADH Question 12 An experimental drug blocks the decarboxylation reactions that convert pyruvate into acetyl-CoA. A cell treated with this drug would not be able to complete glycolysis. a.This is true b.This is false 46 Krebs Cycle Oxidizes the acetyl group from pyruvate Occurs in the matrix of the mitochondria Biochemical pathway of 9 steps in three segments 1.Acetyl-CoA + oxaloacetate citrate 2.Citrate rearrangement and decarboxylation 3.Regeneration of oxaloacetate 47 Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. CoA- (Acetyl-CoA) CoA 4-carbon molecule (oxaloacetate) 6-carbon molecule (citrate) NAD + NADH CO 2 5-carbon molecule NAD + NADH CO 2 4-carbon molecule ADP + P Krebs Cycle FAD FADH 2 4-carbon molecule NAD + NADH ATP Glycolysis Pyruvate Oxidation Electron Transport Chain Chemiosmosis ATP 4-carbon molecule Pyruvate from glycolysis is oxidized Krebs Cycle into an acetyl group that feeds into the Krebs cycle. The 2-C acetyl group combines with 4-C oxaloacetate to produce the 6-C compound citrate (thus this is also called the citric acid cycle). Oxidation reactions are combined with two decarboxylations to produce NADH, CO 2, and a new 4-carbon molecule. Two additional oxidations generate another NADH and an FADH 2 and regenerate the original 4-C oxaloacetate. NADH FADH 2 Krebs Cycle 48 Products of the Krebs Cycle For each Acetyl-CoA entering: Release 2 molecules of CO 2 Reduce 3 NAD + to 3 NADH Reduce 1 FAD (electron carrier) to FADH 2 Produce 1 ATP Regenerate oxaloacetate 49 Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Glycolysis NADH FADH 2 Pyruvate Oxidation ATP Krebs Cycle: The Reactions Citrate synthetase NAD + NADH H2OH2O NAD + NADH CO 2 Isocitrate dehydrogenase Fumarase CoA-SH 1 2 Aconitase CoA-SH NAD + CO NADH CoA-SH GDP + P i Acetyl-CoA CH 3 C S OCoA Krebs Cycle Malate dehydrogenase -Ketoglutarate dehydrogenase Succinyl-CoA synthetase GTP ATP ADP Succinate dehydrogenase FADH 2 89. Reactions 8 and 9: Regeneration of oxaloacetate and the fourth oxidation 7. Reaction 7: The third oxidation 6. Reaction 6: Substrate-level phosphorylation 5. Reaction 5: The second oxidation 4. Reaction 4: The first oxidation 23. Reactions 2 and 3: Isomerization 1. Reaction 1: Condensation Electron T ransport Chain Chemiosmosis Oxaloacetate (4C) CH 2 O C COO Citrate (6C) HO C COO CH 2 Isocitrate (6C) HC COO CH 2 HO CH -Ketoglutarate (5C) CH 2 COO CH 2 C O Succinyl-CoA (4C) CH 2 COO S CoA CH 2 C O Succinate (4C) COO CH 2 COO CH 2 Fumarate (4C) HC CH COO Malate (4C) HO CH COO CH 2 COO FAD 50 At this point Glucose has been oxidized to: 6 CO 2 4 ATP 10 NADH 2 FADH 2 Electron transfer has released 53 kcal/mol of energy by gradual energy extraction Energy will be put to use to manufacture ATP These electron carriers proceed to the electron transport chain Question 5 The 2 carbons in acetylCoA are eventually used to form a.Glucose b.ATP c.Pyruvate d.Oxaloacetate e.Carbon dioxide Learning Objectives Describe the structure and function of the electron transport chain. Diagram how the proton gradient connects electron transport with ATP synthesis. Calculate the number of ATP molecules produced by aerobic respiration. 52 53 Electron Transport Chain (ETC) ETC is a series of membrane-bound electron carriers Embedded in the inner mitochondrial membrane (cristae) Electrons from NADH and FADH 2 are transferred to complexes of the ETC Each complex A proton pump creating proton gradient Transfers electrons to next carrier What Do You See Here?? 54 55 Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Mitochondrial matrix NADH + H + ADP + P i H2OH2O H+H+ H+H+ 2H / 2 O2O2 Glycolysis Pyruvate Oxidation 2 Krebs Cycle ATP Electron Transport Chain Chemiosmosis NADH dehydrogenase bc 1 complex Cytochrome oxidase complex Inner mitochondrial membrane Intermembrane space a. The electron transport chain ATP synthase b. Chemiosmosis NAD + Q C ee FADH 2 H+H+ H+H+ H+H+ H+H+ ee 2 2 ee 2 2 ATP FAD 56 Chemiosmosis Accumulation of protons in the intermembrane space drives protons into the matrix via diffusion Membrane relatively impermeable to ions Most protons can only reenter matrix through ATP synthase Uses energy of gradient to make ATP from ADP + P i 57 ADP + P i Catalytic head Stalk Rotor H+H+ H+H+ Mitochondrial matrix Intermembrane space H+H+ H+H+ H+H+ H+H+ H+H+ ATP Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 58 Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. H2OH2O CO 2 H+H+ H+H+ 2H / 2 O2O2 H+H+ ee H+H+ 32 ATP Krebs Cycle 2 ATP NADH FADH 2 NADH Pyruvate Oxidation Acetyl-CoA ee Q C ee Glycolysis Glucose Pyruvate 59 Please note that due to differing operating systems, some animations will not appear until the presentation is viewed in Presentation Mode (Slide Show view). You may see blank slides in the Normal or Slide Sorter views. All animations will appear after viewing in Presentation Mode and playing each animation. Most animations will require the latest version of the Flash Player, which is available at 60 Energy Yield of Respiration Theoretical energy yield (these values vary from book to book) 38 ATP per glucose for bacteria 36 ATP per glucose for eukaryotes Actual energy yield 30 ATP per glucose for eukaryotes Reduced yield is due to Leaky inner membrane Use of the proton gradient for purposes other than ATP synthesis 61 Chemiosmosis NADH Total net ATP yield = 32 (30 in eukaryotes) ATP Krebs Cycle Pyruvate oxidation FADH 2 Glycolysis 2 Glucose Pyruvate ATP Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Question 7 What is the function of the coenzymes, NADH and FADH 2 ? a.Charging electrons to power ATP synthase b.Catalyzing the formation of acetyl-CoA c.Providing electrons and H+ to the electron transport chain d.Transporting CO 2 into the mitochondria e.Acting as a terminal electron acceptor Question 16 What happens to the electrons energy as it moves through the electron transport chain? a.The electrons gain energy through each transfer b.The electrons lose energy through each transfer c.The energy content is unchanged d.The energy drops to a different orbital Learning Objectives Compare anaerobic and aerobic respiration. What are used as final e - acceptors Distinguish between fermentation and anaerobic respiration. Understand how proteins and fats are used in energy metabolism. 64 65 Oxidation Without O 2 1.Anaerobic respiration Use of inorganic molecules (other than O 2 ) as final electron acceptor Many prokaryotes use sulfur, nitrate, carbon dioxide or even inorganic metals 2.Fermentation Use of organic molecules as final electron acceptor 66 Anaerobic respiration Methanogens CO 2 is reduced to CH 4 (methane) Found in diverse organisms including cows Sulfur bacteria Inorganic sulphate (SO 4 ) is reduced to hydrogen sulfide (H 2 S) Early sulfate reducers set the stage for evolution of photosynthesis Sulfur-Respiring Prokaryotes 67 a: Wolfgang Baumeister/Photo Researchers, Inc.; b: NPS Photo Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. b.a m 68 Fermentation Reduces organic molecules in order to regenerate NAD + 1. Ethanol fermentation occurs in yeast CO 2, ethanol, and NAD + are produced 2. Lactic acid fermentation Occurs in animal cells (especially muscles, such as during sprinting) Electrons are transferred from NADH to pyruvate to produce lactic acid 69 CO 2 2Acetaldehyde 2ADP 2 Lactate Alcohol Fermentation in Yeast 2 ADP Lactic Acid Fermentation in Muscle Cells 2 NAD + 2 NADH 2 ATP CO CO OO CH 3 CO H CO CO OO HCOH CO OO H 2 Ethanol HCOH CH 3 2 Pyruvate Glucose GLYCOLYSISGLYCOLYSIS GLYCOLYSISGLYCOLYSIS Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Question 13 When making wine, grape juice and yeast are sealed into a container. Why must the container be air tight? a.To prevent the buildup of lactic acid b.Fermentation only occurs in the absence of oxygen c.Yeast cannot live in aerobic environments d.To prevent the yeast from dying e.To increase the production of acetyl-CoA 71 Catabolism of Protein Amino acids undergo deamination to remove the amino group Remainder of the amino acid is converted to a molecule that enters glycolysis or the Krebs cycle Alanine is converted to pyruvate Aspartate is converted to oxaloacetate 72 C HOO O C C O O C CO CHH CHH CHH C HH CH2NH2NH NH 3 HO Urea Glutamate -Ketoglutarate Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 73 Catabolism of Fat Fats are broken down to fatty acids and glycerol Fatty acids are converted to acetyl groups by -oxidation Oxygen-dependent process The respiration of a 6-carbon fatty acid yields 20% more energy than 6-carbon glucose. 74 Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. CoA Fatty acid OO C C C H H ATP NADH H2OH2O Krebs Cycle PP i AMP + FADH 2 Fatty acid 2C shorter CoA Fatty acid OH H C C C H H OH O H H C C C H H CoA FAD Fatty acid OH C C C H CoA Fatty acid O HO H C C C H H CoA NAD + Acetyl-CoA 75 Cell building blocks Deamination -oxidation Glycolysis Oxidative respiration Ultimate metabolic products Acetyl-CoA Pyruvate Macromolecule degradation Krebs Cycle Nucleic acidsPolysaccharides NucleotidesAmino acidsFatty acidsSugars ProteinsLipids and fats NH 3 H2OH2OCO 2 Copyright The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Question 8 The process of removing the amino group from an amino acid is a.Decarboxylation b.Defenestration c.Denaturation d.Deamination e.Deracciation Question 9 Beta-oxidation is used to extract energy from a.Glucose b.Proteins c.Nucleic acids d.Carbohydrates e.Triglycerides Question 14 A cheeseburger contains bread, meat and cheese. Which portion of this meal produces the most ATP per unit of mass? a.Bread b.Meat c.Cheese d.All are equal Final Review 79 Question 2 NADH is made during a.Glycolysis b.Pyruvate oxidation c.Krebs cycle d.All of the above Question 3 Most of the ATP made by aerobic respiration is made during a.Glycolysis b.Electron transport chain c.Pyruvate oxidation d.Krebs cycle e.Substrate-level phosphorylation