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Ch 6

Ch 6. Cellular Respiration. Energy for life. ECOSYSTEM. Photosynthesis in chloroplasts. Glucose. CO 2. +. +. H 2 O. O 2. Cellular respiration in mitochondria. ATP. (for cellular work). Heat energy. Breathing vs Cellular Respiration. Breathing- gas exchange

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Ch 6

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  1. Ch 6 Cellular Respiration

  2. Energy for life ECOSYSTEM Photosynthesis in chloroplasts Glucose CO2 + + H2O O2 Cellular respiration in mitochondria ATP (for cellular work) Heat energy

  3. Breathing vs Cellular Respiration • Breathing- gas exchange • Cellular respiration- aerobic harvesting of energy from food molecules by cells

  4. Cellular Respiration • Energy stored in ATP + CO2 H2O C6H12O6 6 ATPs + 6 O2 + 6 Carbon dioxide Glucose Oxygen Water Energy

  5. Cell Respiration

  6. Redox • Oxidation- loss of e- • Reduction- addition of e- Loss of hydrogen atoms (oxidation) C6H12O6 + 6 O2 6 CO2 + 6 H2O + Energy (ATP) Gain of hydrogen atoms (reduction)

  7. Glucose Oxidation • Significant in oxidation f Glucose • Dehydrogenase • NAD+--coenzyme, electron carrier molecule • Becomes NADH • ***FADH Oxidation Dehydrogenase Reduction NAD+ + 2 H NADH + H+ (carries 2 electrons) 2 H+ + 2 e–

  8. Electron Transport Chain • NADH transfer e- to ETC • Redox reactions as e- travel through chain • O2 final e- acceptor • Energy released at each step NADH ATP NAD+ + 2e– Controlled release of energy for synthesis of ATP H+ Electron transport chain 2e– 1  2 O2 H+ H2O

  9. Cell Respiration

  10. Glycolysis • Splits sugar • Breaks Glucose from 6- C sugar into two 3- C sugars • Yields 2 pyruvate molecules • Net gain of 2 ATP, 2 NADH, 2 H2O Glucose 2 ADP 2 NAD+ + 2 P 2 NADH 2 ATP + 2 H+ 2 Pyruvate

  11. Glycolysis • Substrate-level phosphorylation • Transfer of P from substrate to ADP to become ATP • Energy banked in ATP and NADH Enzyme Enzyme P ADP + ATP P P Substrate Product 2 Pyruvate

  12. Glycolysis • 3 “phases” • Energy consuming • Glucose split • Energy producing • G3P is significant intermediate • Glyceraldehyde-3-phosphate

  13. ENERGY INVESTMENT PHASE Glucose ATP Steps – A fuel molecule is energized, using ATP. Step 1 3 1 ADP Glucose-6-phosphate P 2 P Fructose-6-phosphate ATP 3 ADP P P Fructose-1,6-bisphosphate Fig. 6-7c Step A six-carbon intermediate splits Into two three-carbon intermediates. 4 4 Glyceraldehyde-3-phosphate (G3P) P P NAD+ NAD+ Step A redox reaction generates NADH. 5 5 ENERGY PAYOFF PHASE 5 P P NADH NADH + H+ + H+ P P P P 1,3-Bisphosphoglycerate ADP ADP 6 6 ATP ATP P P 3-Phosphoglycerate 7 7 Steps – ATP and pyruvate are produced. P P 6 9 2-Phosphoglycerate 8 8 H2O H2O P P Phosphoenolpyruvate (PEP) ADP ADP 9 9 ATP ATP Pyruvate

  14. Pyruvate • Cannot enter Citric Acid Cycle directly • 3 reactions take place • Carboxyl group removed, given off as CO2 • Remaining 2-C compound oxidized, NAD+ reduced (2 NADH formed) • Coenzyme A combines with 2-C compound to form Acetyl Coenzyme A

  15. Formation of Acetyl CoA  H+ NAD+ NADH 2 CoA Acetyl coenzyme A Pyruvate 1 3 CO2 Coenzyme A

  16. Cell Respiration

  17. Krebs Cycle • AKA the Citric Acid Cycle • Mitochondrial matrix • Starts with Acetyl Coenzyme A • Only Acetyl part joins cycle (2-C) • Coenzyme A is recycled • Nets 2 CO2, 3 NADH, 1 FADH2 and 1 ATP per turn • 1 glucose=2 pyruvate=2 Acelty CoA=2 turns Kreb Cycle

  18. Krebs Cycle

  19. Cell Respiration

  20. Oxidative Phosphorylation • Stage where most ATP is produced • Membrane of mitochondria • 2 parts • ETC • Chemiosmosis • ETC creates gradient • Chemiosmosis uses gradient to generate ATP

  21. Oxidative Phosphorylation H+ H+ H+ H+ H+ Protein complex of electron carriers H+ H+ Electron carrier H+ ATP synthase H+ Intermembrane space Inner mitochondrial membrane FADH2 FAD Electron flow H+ O2 + 2 1  2 NAD+ NADH H+ H+ Mitochondrial matrix ADP + P ATP H+ H2O H+ Electron Transport Chain Chemiosmosis OXIDATIVE PHOSPHORYLATION

  22. Overall • Start with 1 glucose molecule • Split into 2 pyruvate in Glycolysis • Yields 2 ATP, 2 NADH, 2 H20 • 2 Pyruvate converted to 2 Acetyl CoA • Yields 2 NADH • Acetyl CoA enters Kreb Cycle • Yields 2 ATP, 6 NADH, 2 FADH (per glucose) • Oxidative Phosphorylation • Yields 34 ATP

  23. ATP yield Electron shuttle across membrane Cytoplasm Mitochondrion 2 2 NADH NADH (or 2 FADH2) FADH2 2 6 2 NADH NADH GLYCOLYSIS OXIDATIVE PHOSPHORYLATION (Electron Transport and Chemiosmosis) 2 Pyruvate 2 Acetyl CoA CITRIC ACID CYCLE Glucose  2 ATP  about 34 ATP  2 ATP by oxidative phosphorylation by substrate-level phosphorylation by substrate-level phosphorylation About 38 ATP Maximum per glucose:

  24. Stopping the chain • Poisons can act during Oxidative Phosphorylation • Rotenone • Blocks ETC by binding to e- carrier molecules • Cyanide, CO • Blocks ETC by binding to e- carrier molecules • O2 cannot accept e- • Oligomycin • Blocks ATP synthase • Uncouplers (DNP) • Creates leaky membrane

  25. Cyanide, carbon monoxide Rotenone Oligomycin H+ H+ ATP synthase H+ H+ H+ H+ H+ Fig. 6-11 DNP FADH2 FAD O2 + 2 1  2 H+ NADH NAD+ H+ ATP ADP + P H+ H2O H+ Chemiosmosis Electron Transport Chain

  26. Alternate Pathways • Aerobic v Anaerobic • Obligate anaerobes • Facultative anaerobes

  27. Fermentation • Anaerobic • Allows cells to generate ATP in absence of O2 • Regenerates NAD+ to break down glucose • Only yields 2 ATP • Lactic Acid in animal muscles • Ethanol in bacteria and yeast

  28. Fermentation Glucose Glucose 2 NAD+ 2 2 ADP NAD+ 2 ADP  P 2  P 2 GLYCOLYSIS GLYCOLYSIS 2 ATP 2 NADH 2 NADH 2 ATP 2 Pyruvate 2 Pyruvate 2 NADH NADH 2 CO2 2 released NAD+ 2 NAD+ 2 2 Ethanol 2 Lactate Lactic acid fermentation Alcohol fermentation

  29. We eat more than just glucose • Different foods enter the process at different stages • Typically broken down before entering cycles

  30. Food, such as peanuts Fig. 6-15 Carbohydrates Fats Proteins Amino acids Glycerol Sugars Fatty acids Amino groups OXIDATIVE PHOSPHORYLATION (Electron Transport and Chemiosmosis) CITRIC ACID CYCLE Acetyl CoA Glucose G3P Pyruvate GLYCOLYSIS ATP

  31. ETC • http://www.youtube.com/watch?v=Idy2XAlZIVA&feature=related • http://www.youtube.com/watch?v=xbJ0nbzt5Kw • Glycolysis • http://www.youtube.com/watch?v=x-stLxqPt6E • Kreb • http://www.youtube.com/watch?v=aCypoN3X7KQ&feature=related • Overview • http://www.youtube.com/watch?v=iXmw3fR8fh0 • Fermentation • http://www.youtube.com/watch?v=y_k8xLrBUfg

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