The oxygen-dependent reactions required for cellular respiration were originally thought to occur in a linear pathway.By using a competitive inhibitor for one enzyme in the pathway, investigators discovered that these reactions occur in a cycle.Which product in the reaction pathway builds up when the inhibitor is added?

Question

Quizplus · Accepted Answer

If a competitive inhibitor is added for one enzyme in the linear pathway, then the product immediately downstream of the inhibited enzyme will build up. Since the question mentions that the reactions occur in a cycle (implying a circular pathway), we can look for the product immediately downstream of the inhibited enzyme in a circular pathway. The product produced immediately after succinate dehydrogenase (the enzyme that would be inhibited by the competitive inhibitor) is succinate. Therefore, if succinate dehydrogenase is inhibited, succinate will build up.

The Oxygen-Dependent Reactions Required for Cellular Respiration Were Originally Thought