Chapter 9 Harvesting chemical energy

1. Chapter 9 – Harvesting chemical energy What pathways capture chemical energy for cellular work? What are the inputs and outputs for each pathway? Where in the cell are these pathways located? Under what conditions do these pathways operate? How are these pathways regulated? How do these pathways connect with the rest of cellular metabolism?

2. Cellular Energy Pathways Carbs ? 6 carbon sugars – organic carbon Pyruvate ? 3 carbon sugarCarbs ? 6 carbon sugars – organic carbon Pyruvate ? 3 carbon sugar

3. Energy metabolism in prokaryotes Living organisms must have some way to capture energy - Food is the electron donors who donate electrons to carriers (NADH) which give it to the transport chain. Living organisms must have some way to capture energy - Food is the electron donors who donate electrons to carriers (NADH) which give it to the transport chain.

4. Sequence of reactions create incremental releases of energy which eventually creates ATPSequence of reactions create incremental releases of energy which eventually creates ATP

5. Proton gradient across the plasma membrane drives chemisosmotic ATP synthesis (oxidative phosphorylation) and other reactions in prokaryotes ATP synthesis is in the mitochondria ? active transport reactionsATP synthesis is in the mitochondria ? active transport reactions

6. Cellular locations of energy pathways

7. Q: ATP is a short-term energy-storage compound. the cell’s principle compound for energy transfers. a molecule all living cells rely on to do work. one of the four building blocks of RNA all of the above

8. Structures of ATP, ADP and AMP

9. Oxidized and reduced forms of NAD A lot of potential energy in NADHA lot of potential energy in NADH

10. Initial steps of glycolysis use 2 ATPs, split glucose to 2 G3P

11. Q: In the first reaction of glycolysis, hexokinase couples phosphorylation of glucose to hydrolysis of ATP. The phosphorylation of glucose has a free energy change of +3.3 kcal/mol, whereas the hydrolysis of ATP has a free energy change of -7.3 kcal/mol. This coupled reaction is: respiration. a redox reaction. overall exergonic. overall endergonic. fermentation.

12. As 2 G3Ps are oxidized to 2 pyruvates, 2 NADH are produced...

13. ...and 4 ATPs

14. ATP synthesis by substrate-level phosphorylation

15. Q: During glycolysis, for each mole of glucose oxidized to pyruvate 6 moles of ATP are produced. 4 moles of ATP are used, and 2 moles of ATP are produced. 2 moles of ATP are used, and 4 moles of ATP are produced. 2 moles of ATP are used, and 2 moles of ATP are produced. net 4 moles of ATP are produced.

16. Changes in free energy during glycolysis GOOD GRAPH!!!!!!!! Oxidation to CO2 is -636 kcal/molGOOD GRAPH!!!!!!!! Oxidation to CO2 is -636 kcal/mol

17. Q: To maintain glycolysis at a high rate, a non-respiratory cell must generate: NADH. Oxygen. More ATP. Acetyl-CoA. NAD+. A non-respiratory cell needs to generate NAD+ because that will run out during high rates of glycolysis due to the rapid use of NAD+ in creating NADH!!!!A non-respiratory cell needs to generate NAD+ because that will run out during high rates of glycolysis due to the rapid use of NAD+ in creating NADH!!!!

18. Fermentation converts pyruvate to lactic acid or ethanol Fermentation occurs when there is no respirationFermentation occurs when there is no respiration

20. Overview of eukaryotic energy pathways

21. Q: Which photo shows plant mitochondria?

22. In aerobic conditions, pyruvate is oxidized to acetyl CoA Oxidize pyruvate and transfer electrons Take a Carbon from Pyruvate to create CO2Oxidize pyruvate and transfer electrons Take a Carbon from Pyruvate to create CO2

23. Citric acid cycle generates ATP, NADH and FADH2 by oxidizing acetate to CO2 TCA cycle or Krebs cycle ? occurs in the mitochondrial matrix Know the main inputs (acetyl CoA created from pyruvate) ? and know the main outputs (ATP, NADH, CO2, FADH2)TCA cycle or Krebs cycle ? occurs in the mitochondrial matrix Know the main inputs (acetyl CoA created from pyruvate) ? and know the main outputs (ATP, NADH, CO2, FADH2)

24. Citric acid cycle releases (and captures) more free energy than does glycolysis Captured all of the available energy in glucoseCaptured all of the available energy in glucose

25. Q: Which of the following is produced during the citric acid cycle? FAD Pyruvate Reduced electron carriers Lactic acid Water

26. Citric acid cycle inputs and products Inputs: Acetate (as acetyl-CoA), water, NAD+ and FAD, ADP, Pi Products: CO2, NADH, FADH2, ATP per glucose (2 acetyl-CoA enters cycle): 4 CO2, 6 NADH + 6 H+, 2FADH2, and 2ATP are generated Some free energy is captured as GTP/ATP, but most as reduced electron carriers NADH, FADH2 Important ? STUDY THIS!!!Important ? STUDY THIS!!!

27. Respiration charges a proton gradient & powers ATP synthesis via chemiosmosis ~10 protons pumped across the membrane per NADH~10 protons pumped across the membrane per NADH

28. Free energy changes in the respiratory chain BE aware of: Terminal Electron Acceptor ? OxygenBE aware of: Terminal Electron Acceptor ? Oxygen

29. Chemiosmotic synthesis of ATP

30. The F1 ATPaseHarvard Video www.sigmaaldrich.com/Area_of_Interest/Life_science/metabolomics/key_resources/metabolic_pathwayswww.sigmaaldrich.com/Area_of_Interest/Life_science/metabolomics/key_resources/metabolic_pathways

31. Total ATP production from glycolysis and respiration The times 2 is because each glucose creates 2 pyruvates and therefore 2 acetyl CoA’s Mitochondria: 8*3 = 24 ATP’s 4 ATP from FADH 2 ATP 36-38 ATP per glucose overallThe times 2 is because each glucose creates 2 pyruvates and therefore 2 acetyl CoA’s Mitochondria: 8*3 = 24 ATP’s 4 ATP from FADH 2 ATP 36-38 ATP per glucose overall

32. Q: How will excess acetyl-CoA affect the rates of glycolysis and the citric acid cycle? Both will increase Both will decrease Glycolysis will increase, citric acid cycle will decrease Glycolysis will decrease; the citric acid cycle will increase Neither will change

33. Q: During intense exercise, as muscles go into anaerobiosis, the body will increase its consumption of: fats proteins carbohydrates All of the above Citric acid cycle and pyruvate oxidation do not occur in anaerobiosis.Citric acid cycle and pyruvate oxidation do not occur in anaerobiosis.

34. What do the following have in common? Both have specialized mechanisms for thermal regulationBoth have specialized mechanisms for thermal regulation

35. Q: Petite mutants of yeast have defective mitochondria incapable of oxidative phosphorylation. What carbon sources can these mutants use to grow? Glucose Fatty acids Pyruvate All of the above None of the above Concept 9.6 (7th ed) Concept 9.6 (7th ed)

36. Thermogenesis in philodendrons

37. Brown fat in newborn mammals Maintains body temperature after leaving the womb ? mostly fat cells permeated with red blood vessels. Thermogenin or mito uncoupling potein ? facilitated diffusion of protons across the membrane . All this energy is wasted as heat ? only purposeMaintains body temperature after leaving the womb ? mostly fat cells permeated with red blood vessels. Thermogenin or mito uncoupling potein ? facilitated diffusion of protons across the membrane . All this energy is wasted as heat ? only purpose

38. Q: Some drugs known as uncouplers facilitate diffusion of protons across the mitochondrial inner membrane. When such a drug is added, what will happen to ATP synthesis and oxygen consumption? Both ATP synthesis and oxygen consumption will decrease ATP synthesis will increase, oxygen consumption will decrease Both ATP synthesis and oxygen consumption will increase ATP synthesis will decrease, oxygen consumption will stay the same There will be no effect on ATP synthesis or oxygen consumption