Cellular Respiration and Fermentation

Glycolysis and cellular respiration are catabolic pathways that release chemical potential energy of glucose in the readily usable form of ATP. In the cytosol, glucose is broken down into 3-carbon pyruvate molecules which either enters the mitochondria if O2 is available, or stays in the cytosol to undergo fermentation which makes NAD+ (a glycolysidic substrate) available for the process of glycolysis to continue.

Here are a few questions to help test your understanding.

1. In the figure below: what are the three stages of cellular respiration (labels a, b, c)?
2. What do the arrows labeled d represent?
3. In the figure below: specify if ATP is produced by substrate-level phosphorylation OR oxidative phosphorylation (labels e, f, g).
4. In the reaction: C6H12O6 + 6 O2 → 6 CO2 + 6 H20, what becomes reduced and what becomes oxidized?
5. How many molecules of CO2 are generated for each molecule of acetyl-CoA introduced into the citric acid cycle?
6. Provide the correct terms for the labels of the diagram below. Grey balls represent carbon atoms.
7. What is the role of oxygen in cellular respiration?
8. Provide terms for the labels of the oxidative phosphorylation diagram below.
9. What are the numbers for the tally of ATP yield from the oxidation of one glucose molecule? Use the diagram below to add the tally from each of the processes.
10. Why does fermentation produce less ATP than cellular respiration?
11. At what point do fats enter the catabolic pathway? At what point do proteins enter the catabolic pathway?