1. Electron Transport Chain
Cellular Respiration Part I: Glycolysis and the Krebs Cycle
Krebs
Cycle
Glycolysis
Electron Transport Chain

2. Remember! Cell respiration is an exergonic reaction
Energy released is used to make ATP

3. Cellular respiration uses enzyme-catalyzed reactions to harvest energy from simple carbohydrates.

4. Add in to your notes:
These can be catabolized into glucose for use in glycolysis:
Carbohydrates (most common)
Lipids (more energy than carbs)
Proteins (starving  pull from muscles   )

5. The Three Steps of Cellular Respiration
Krebs
Cycle
Glycolysis
Electron Transport Chain

7. Summary: Glycolysis: the breakdown of one glucose molecule into two pyruvate. It occurs in the cytoplasm and is anaerobic.

8. Glycolysis: Summary Investment: Payoff: Glucose 2 ATP 2 NAD+
2 Pyruvate
2 ATP (4 made, but 2 used)
2 NADH
Oxidation
Reaction

9. Glycolysis ends with pyruvate.
Energy is stockpiled in pyruvate
If oxygen is present, pyruvate enters mitochondria in eukaryotes (and stays in ctyosol of prokaryotes)
The oxidation of glucose continues!

11. CoA makes it very reactive- has high potential energy!
Pyruvate is transported from the cytoplasm to the mitochondrion, where it is converted to Acetyl CoA.
CoA makes it very reactive- has high potential energy!
Which functional group is removed?

12. Transition Reaction Summary:
Investment:
2 Pyruvate
Payoff:
2 Acetyl Coenzyme A
2 NADH
2 CO2 (waste product)

13. The Krebs Cycle (Also known as the Citric Acid Cycle or the TCA Cycle)

15. SUMMARY: The Krebs Cycle occurs in the matrix of the mitochondria.

16. SUMMARY: The Krebs Cycle produces 2 ATP through substrate-level phosphorylation. (1 glucose=2 pyruvate…so this happens 2x per glucose)

17. During the Krebs Cycle , coenzymes NAD+ and FADH each receive high energy electrons and become NADH and FADH2.

18. The Krebs Cycle Summary:
Investment:
2 Acetyl CoA
Payoff:
2 ATP
6 NADH
2 FADH2
4 CO2 (waste)
Substrate-Level
Phosphorylation

19. In glycolysis and the Krebs Cycle…
ATP is made by substrate-level phosphorylation
Enzyme directly transfers a phosphate group to ADP from a substrate
In the ETC, it is made by oxidative phosphorylation (using a series of proteins)

20. Summary so far. Next…the ETC!
Glycolysis
Transition
Reaction
Krebs Cycle
Investment:
Glucose
2 ATP
2 NAD+
Investment:
2 Pyruvate
Investment:
2 Acetyl CoA
Payoff:
2 Pyruvate
2 ATP (4 made, 2 used)
2 NADH
Payoff:
2 Acetyl Coenzyme A
2 NADH
2 CO2 (waste product)
Payoff:
2 ATP
6 NADH
2 FADH2
4 CO2 (waste)
Oxidation
Reaction
Substrate-Level
Phosphorylation

21. REMEMBER!
This is happening in multiple places within a cell at any given time
This is happening in all cells at any given time