1. Cellular Respiration: Harvesting Chemical Energy

2. Rs - Equation C 6 H 12 O 6 + 6 O 2 6 CO 2 + 6 H 2 O and energy The energy is released from the chemical bonds in the complex organic molecules.

3. Respiration - Preview u The process of releasing Energy from food. u Food - Stored Energy in chemical bonds. u ATP - Useable Energy for cell work.

4. Oxidation- Reduction Reactions u Transfer of one or more electrons (e - ) from one reactant to another u Redox Reactions

5. Oxidation - definitions u Loss of electrons. u Loss of energy. u Loss of Hydrogens

6. Reduction - definitions u Gain of electrons. u Gain of energy. u Gain of Hydrogens

7. Redox reactions

8. Generalized Reaction u Xe - + Y  X + Ye - u X = reducing agent (substance being oxidized) u Y = oxidizing agent (substance being reduced)

9. Redox reactions u Reactions are usually paired or linked together. u Look for these links as we study Respiration (Rs). u Many of the reactions will be done by phosphorylation

10. Cellular Respiration u Overall Equation: u Which substance is being oxidized, which is being reduced?

11. Phosphorylation u Adding a phosphate group to a molecule. u The phosphate group adds “energy” to the molecule for chemical reactions.

12. Two Types of Phosphorylation u Substrate-Level Phosphorylation u Small amount of ATP formed this way in cells u Oxidative Phosphorylation or Chemiosmotic Phosphorylation u Most ATP formed this way in cells

13. Substrate -Level Phosphorylation u Formation of ATP from ADP and an inorganic phosphate (Pi) ADP + Pi  ATP (endergonic rxn) u Energy is required - comes from an exergonic reaction in the cell u An enzyme transfers a phosphate group (P i ) from a substrate molecule to ADP

14. Substrate-Level Phosphorylation

15. Oxidative or Chemiosmotic Phosphorylation u H+ atoms are deposited into the outer compartment of mitochondria and this creates an “electrochemical” gradient across the membrane u As H+ atoms move from [high] to [low] energy is given off u This energy is captured by ADP + P i to produce ATP

17. Cell Respiration - 4 parts 1. Glycolysis: 10 step process in cytoplasm 2. Pyruvate Oxidation: 1 step process in mitochondrial matrix 3. Krebs Cycle (Citric Acid Cycle): 8 step cyclical process in mitochondrial matrix 4. Electron Transport and Chemiosmosis: a multistep process in inner mitochondrial membrane

18. 3 Goals of Rs u 1. Break bonds between 6C glucose to make 6CO 2 u 2. Move H+ from glucose to oxygen, forming 6H 2 O u 3. Trap as much free energy in the form of ATP

19. Glycolysis u Glyco- glucose. u -lysis: to split u Universal step in all Rs types. u Likely to be earliest type of cell energy processes.

20. Glycolysis u Function - To split glucose and produce NADH and ATP. u Location - Cytoplasm.

21. Overview of Glycolysis

22. Glycolysis -Requirements u Glucose u 2 ATP u 4 ADP u 2 NAD +

23. Glycolysis - Products u 2 Pyruvic Acids (pyruvate) u (a 3C acid) u 2 ADP u 4 ATP u 2 NADH

24. Net Result u 2 ATP per glucose u 2 NADH

26. Energy Investment Phase

27. Energy Harvest Phase

28. Pyruvate Oxidation - occurs twice for each pyruvate u Transition step between Glycolysis and Krebs Cycle u Occurs between cytoplasm and mitochondrial matrix 1. Removes CO 2 from pyruvate to form acetate molecule 2. Forms NADH + H + 3. Co-enzyme A attaches to acetate molecule

29. Formation of Acetyl CoA

30. Structure of Mitochondrion  See separate handout

31. Krebs Cycle u Also called: u Citric Acid Cycle u Tricarboxylic Acid Cycle

32. Krebs Cycle u Function: Oxidize Acetyl coA to CO 2 u Produce NADH and FADH 2 u Location: Mitochondrial matrix

33. Krebs Cycle -Requirements u Acetly coA (2C) u 3 NAD + u 1 ADP u 1 FAD u Double this list for each glucose.

34. Krebs Cycle - Products u 2 CO 2 u 3 NADH u 1 ATP u 1 FADH 2 u Double this list for each glucose.

37. Krebs Cycle u Produces most of the cell's energy in the form of NADH and FADH 2 u Does NOT require O 2

38. Comment u The ATPs produced directly in Krebs Cycle and in Glycolysis are by: u Substrate-level phosphorylation u The P i group is transferred from a substrate to ADP.

39. Electron Transport Chain u ETC or Electron Transport System (ETS). u A collection of proteins that are structurally linked into units.

40. ETC u Uses sets of Cytochromes, Fe containing proteins to pass electrons. u The Cytochromes alternate between RED and OX forms and pass electrons down to O 2

42. ETC u Function: Convert NADH and FADH 2 into ATP. u Location: Mitochondria cristae.

43. ETC - Requirements u NADH or FADH 2 u ADP uO2uO2

44. ETC - Products u NAD + and FAD u ATP uH2OuH2O

46. ETC - ATP Yields u Each NADH -- 3 ATP u Each FADH 2 -- 2 ATP

47. Chemiosmotic Hypothesis u ETC energy is used to move H + (protons) across the cristae membrane. u ATP is generated as the H + diffuse back into the matrix.

49. ATP Synthase u Uses the flow of H + to make ATP. u Works like an ion pump in reverse, or like a waterwheel under the flow of H + “water”.

51. Alcoholic Fermentation u Done by yeast, a kind of fungus.

53. Movie

54. Alcoholic Fermentation u Uses only Glycolysis. u An incomplete oxidation - energy is still left in the products (alcohol). u Does NOT require O 2 u Produces ATP when O 2 is not available.

56. Lactic Acid Fermentation u Uses only Glycolysis. u An incomplete oxidation - energy is still left in the products (lactic acid). u Does NOT require O 2 u Produces ATP when O 2 is not available.

57. Movie

59. Lactic Acid Fermentation u Done by human muscle cells under oxygen debt. u Lactic Acid is a toxin and causes soreness and stiffness in muscles.

60. Fermentation - Summary u Way of using up NADH so Glycolysis can still run. u Provides ATP to a cell even when O 2 is absent.

62. Aerobic vs Anaerobic u Aerobic - Rs with O 2 u Anaerobic - Rs without O 2 u Aerobic - All three Rs steps. u Anaerobic - Glycolysis only.

63. Strict vs. Facultative u Strict - can only do Rs this one way. u Facultative - can switch Rs types depending on O 2 availability. Ex - yeast

64. Question u Since yeast can do both aerobic and anaerobic Rs, which is the better process if given a choice? u Check the ATP yields from both processes.

65. ATP yields by Rs type u Anaerobic - Glycolysis only Gets 2 ATPs per glucose. u Aerobic - Glycolysis, Krebs, and ETC. Generates many more ATPs per glucose.

66. Aerobic ATP yield u Glycolysis - 2 ATPS, 2 NADHs u Krebs - 2 ATPS, 8 NADHs, 2 FADH 2 u Each NADH = 3 ATP u Each FADH 2 = 2 ATP

67. ATP Sum u 10 NADH x 3 = 30 ATPs u 2 FADH 2 x 2 = 4 ATPs u 2 ATPs (Gly) = 2 ATPs u 2 ATPs (Krebs) = 2 ATPs u Max = 38 ATPs per glucose

68. However... u Some energy is used in shuttling the NADH from Glycolysis into the mitochondria. u Actual ATP yield ~ 36/glucose

69. Yeast u Would rather do aerobic Rs; it has 18x more energy per glucose. u But, anaerobic will keep you alive if oxygen is not present.

70. Importance of Rs u Convert food to ATP. u Provides materials for use in other cellular pathways.

71. Other Importances of Respiration u Alcohol Industry - almost every society has a fermented beverage. u Baking Industry - many breads use yeast to provide bubbles to raise the dough.

72. Summary u Know the 3 main reactions (plus pyruvate oxidation) of Rs and the 4 required items for each. u Appreciate the importances of Rs.