MCAT Biochemistry Question 145: Answer and Explanation

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Question: 145

10. Why is it preferable to cleave thioester links rather than typical ester links in aerobic metabolism?

  • A. Oxygen must be conserved for the electron transport chain.
  • B. Thioester hydrolysis has a higher energy yield.
  • C. Typical ester hydrolysis cannot occur in vivo.
  • D. Thioester cleavage requires more energy.

Correct Answer: B

Explanation:

Thioester links release a great deal of energy when hydrolyzed, making them well-suited as respiration reaction drivers. They are particularly useful because they release more energy than typical ester cleavage. It is thioester formation, not hydrolysis, that requires a great deal of energy, making choice (D) incorrect.

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