Which of the following is true concerning the rate-limiting step in a metabolic pathway?
A)It is likely to be the slowest reaction in the pathway,and it is always the last step in a metabolic pathway.
B)It is likely to be the fastest reaction in the pathway,and it is always the last step in a metabolic pathway.
C)It is always the first step in the pathway,and may be subject to end-product inhibition.
D)It is likely to be the slowest reaction in the pathway,and it may be subject to end-product inhibition.
E)It is likely to be the fastest reaction in the pathway,and it may be subject to end-product inhibition.

Question

Quizplus · Accepted Answer

The rate-limiting step is the slowest reaction in a metabolic pathway and may be subject to end-product inhibition, where the end product of the pathway inhibits the enzyme that catalyzes the rate-limiting step. It is not always the last step in the pathway or the first step in the pathway, so choices A and C are incorrect. Choice B is also incorrect because the rate-limiting step cannot be the fastest reaction in the pathway.

Which of the Following Is True Concerning the Rate-Limiting Step