Concept Questions

Take some time to write answers to these questions. If you can answer them, you have a good grasp of the material!

1. Show diagrammatically the interaction of holoenzyme and its substrate and general products that can be formed from a reaction.

2. Give the general name of the enzyme that:

synthesizes ATP;
digests RNA;
carries out the transformation from DHAP to G-3-P (step 4 in glycolysis);
catalyzes the formation of acetyl from pyruvic acid (just before step 1 in the TCA cycle);
reduces pyruvic acid to lactic acid; and reduces nitrate to nitrate

3. Explain what an allosteric enzyme is and how negative feedback works. Two steps in glycolysis are catalyzed by allosteric enzymes. These are: (1) phosphofructokinase, which catabolizes step 3, and (2) pyruvate kinase, which catabolizes step 9. Suggest what metabolic products might regulate these enzymes. How might one place these regulators in figure 8.19?

4. Explain how oxidation of a substrate proceeds without oxygen.

5. In the following redox pairs, which compound is reduced and which is oxidized?

NAD and NADH
FADH2 and FAD
lactic acid and pyruvic acid
NO3 and NO2
ethanol and acetaldehyde

6. Discuss the relationship of anabolism to catabolism

of ATP to ADP
of glycolysis to fermentation
of electron transport to oxidative phosphorylation

7. What is meant by the concept of the "final electron acceptor"? What are the final electron acceptors in aerobic, anaerobic, and fermentative metabolism?

8. Name the major ways that substrate-level phosphorylation is different from oxidative phosphorylation.

9. Compare the location of glycolysis, TCA cycle, and electron transport in procaryotic and eucaryotic cells.

10. Outline the basic steps in glycolysis, indicating where ATP is used and given off. Where does NADH originate, and what is its fate in an aerobe? What is its fate in a fermentative organism?

11. What is the source of ATP in the TCA cycle?

12. How many ATPs are formed from the original glucose molecule? How many ATPs would be formed as a result of aerobic respiration if cytochrome oxidase were missing from the respiratory chain (as is the case with many bacteria)?

13. Summarize the chemiosmotic theory of ATP formation. What is unique about the actions of ATP synthase?

14. How are aerobic and anaerobic respiration different?

15. Compare the general equation for aerobic metabolism with table 8.4 and verify that all figures balance.

16. Water is one of the end products of aerobic respiration. Where in the metabolic cycles is it formed, and where is it used?

17. Briefly outline the use of certain metabolites of glycolysis and TCA in amphibolic pathways.

2002 McGraw-Hill Higher Education
Any use is subject to the Terms of Use and Privacy Policy.
McGraw-Hill Higher Education is one of the many fine businesses of The McGraw-Hill Companies.