Question

Which of the following statements is not true of the TCA cycle?

A) Oxidation occurs at three steps in the TCA cycle.
B) Decarboxylation occurs at two steps in the TCA cycle.
C) ATP/GTP is generated at one point by substrate-level phosphorylation.
D) Acetate enters the TCA cycle and joins a four-carbon acceptor molecule to form citrate.
E) FAD is an electron acceptor in the cycle.

Answer 1

The false statement regarding the TCA cycle is that acetate joins a four-carbon acceptor molecule to form citrate; it is actually the acetyl group from acetyl CoA that enters the cycle and combines with oxaloacetate to form the six-carbon molecule citrate.

Step-by-step explanation:

The TCA cycle, also known as the citric acid cycle or Krebs cycle, is a crucial part of cellular respiration where acetyl CoA is oxidized to produce energy carriers and carbon dioxide. The statement that is not true of the TCA cycle is 'Acetate enters the TCA cycle and joins a four-carbon acceptor molecule to form citrate.' Instead, the acetyl group from acetyl CoA enters the TCA cycle by combining with oxaloacetate, not acetate, to form citrate. Oxidation occurs at three steps in the TCA cycle, decarboxylation occurs at two steps, and ATP/GTP is generated at one point by substrate-level phosphorylation. Moreover, FAD does indeed serve as an electron acceptor in the cycle.