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Biochemistry

Biochemistry. Lecture 10. Only a Small Amount of Energy Available in Glucose is Captured in Glycolysis. Glycolysis. 2. G’° = -146 kJ/mol. GLUCOSE. Full oxidation (+ 6 O 2 ). 6 CO 2 + 6 H 2 O. G’° = -2,840 kJ/mol. Cellular Respiration: the big picture.

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Biochemistry

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  1. Biochemistry Lecture 10

  2. Only a Small Amount of Energy Available in Glucose is Captured in Glycolysis Glycolysis 2 G’° = -146 kJ/mol GLUCOSE Full oxidation (+ 6 O2) 6 CO2 + 6 H2O G’° = -2,840 kJ/mol

  3. Cellular Respiration: the big picture • process in which cells consume O2 and produce CO2 • provides more energy (ATP) from glucose than glycolysis • also captures energy stored in lipids and amino acids • evolutionary origin: developed about 2.5 billion years ago • used by animals, plants, and many microorganisms • occurs in three major stages: • acetyl CoA production • acetyl CoA oxidation • electron transfer and oxidative phosphorylation

  4. Stage 1. Acetyl-CoA production

  5. Stage 2. Acetyl-CoA Oxidation

  6. Stage 3. Electron Transfer and oxidative Phosphorylation

  7. Where does this all happen?

  8. Stage 1. Acetyl-CoA production

  9. Pyruvate Decarboxylation

  10. The PDC

  11. Sequence of Events in Pyruvate Decarboxylation • Step 1: Decarboxylation of pyruvate to an aldehyde • Step 2: Oxidation of aldehyde to a carboxylic acid • Step 3: Formation of acetyl CoA • Step 4: Reoxidation of the lipoamide cofactor • Step 5: Regeneration of the oxidized FAD cofactor

  12. Structure of CoA

  13. Stage 2. Acetyl-CoA Oxidation

  14. Step 1

  15. Step 2

  16. Sterospecificity

  17. Step 3

  18. Step 4

  19. Step 5.

  20. 1/2 * 1/2 Carbons are scrambled at succinate * Succinyl-CoA Synthetase Succinyl-CoA * Succinate dehydrogenase Succinate

  21. Step 6.

  22. Step 7.

  23. Products from one turn of the cycle

  24. Acetyl-CoA + 3NAD+ + FAD + GDP + Pi + 2 H2O 2CO2 +3NADH + FADH2 + GTP + CoA + 3H+ Net Effect of the Citric Acid Cycle • carbons of acetyl groups in acetyl-CoA are oxidized to CO2 • electrons from this process reduce NAD+ and FAD • one GTP is formed per cycle, this can be converted to ATP • intermediates in the cycle are not depleted

  25. Energy Yield

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