How does the addition of coenzyme A, a sulfur-containing molecule derived from a B vitamin, function in the subsequent reaction?
A) It provides the sulfur needed for the molecule to enter the mitochondrion.
B) It utilizes this portion of a B vitamin, which would otherwise be a waste product from another pathway.
C) It provides a relatively unstable molecule whose acetyl portion can be readily transferred to a compound in the citric acid cycle.
D) It drives the reaction that regenerates NAD+.
E) It removes one molecule of CO2.

Question

Quizplus · Accepted Answer

Coenzyme A acts as a carrier for the acetyl group, forming acetyl-CoA, which is the entry point for the citric acid cycle. The high-energy thioester bond between coenzyme A and the acetyl group is susceptible to hydrolysis, allowing transfer of the acetyl group to the citric acid cycle intermediate, oxaloacetate. This reaction is energetically favorable and drives the citric acid cycle forward.

How Does the Addition of Coenzyme A, a Sulfur-Containing Molecule