The reaction in which malate is oxidized to oxaloacetate is not thermodynamically favored. It takes place because
A) it is coupled to ATP hydrolysis.
B) it involves substrate-level phosphorylation.
C) the product is continuously used up in the next reaction of the cycle, which is thermodynamically favored.
D) it is coupled to a strong reduction.

Question

Quizplus · Accepted Answer

The reaction of malate being oxidized to oxaloacetate in the citric acid cycle is not thermodynamically favored on its own. However, it proceeds because the oxaloacetate produced is continuously consumed in the next step of the cycle, where acetyl-CoA is added to oxaloacetate to form citrate, a reaction that is thermodynamically favored. This continuous use of the product helps pull the reaction forward.

The Reaction in Which Malate Is Oxidized to Oxaloacetate Is