21. The Generation of Biochemical Energy

Which enzyme oxidizes α-ketoglutarate in step 4 of the citric acid cycle?

Which one of the following enzymes catalyzes the addition of water to the C=C bond in fumarate?

How many final high-energy molecules are produced in phase C of the citric acid cycle?

Which reaction of the citric acid cycle produces ATP directly?

Identify the two reactions that involve oxidation and decarboxylation.

Write the name for the substrate, enzyme, and product of reaction 6 of the citric acid cycle.

Write the name of the substrate and the enzyme of reaction 8 of the citric acid cycle.

What is the name of the enzyme for the reaction that produces a GTP molecule in the citric acid cycle?

Which reactions of the citric acid cycle produce NADH?

Complete the following net equation for one turn of the citric acid cycle.

Acetyl CoA + __H₂O + 3 NAD+ + FAD + GDP + ____ ⭢  CoA + ___NADH + ___H⁺ + FADH₂ + GTP + ___CO₂

Look ahead to Figure 21.8 for the citric acid cycle.

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a. Draw the structures of the reactants in steps 3, 6, and 8, and indicate which hydrogen atoms are removed in these reactions.

Why, do you suppose, the coenzyme for the reaction in the citric acid cycle that is catalyzed by succinate dehydrogenase is FAD and not NAD⁺?

Identify the participants in the citric acid cycle that contain alcohol groups. Identify these groups as primary, secondary, or tertiary alcohols.

Which of the reactants in the citric acid cycle have two chiral carbon atoms?

Since no molecular oxygen participates in the citric acid cycle, the steps in which acetyl groups are oxidized to CO₂ involve removal of hydride ions and hydrogen ions. What is the acceptor of hydride ions? What is the acceptor of hydrogen ions?