Answer to Question #115698 in Biochemistry for Nootshy Romage

Question

1. Consider a liver cell carrying out the oxidation of glucose under aerobic conditions. Suppose that we added a very potent and specific inhibitor of the mitochondrial ATP synthase, completely inhibiting this enzyme. Indicate whether each of the following statements about the effect of this inhibitor is true or false; explain in a sentence or two why. [10 pts]

____ (A) ATP production in the cell will quickly drop to zero.





____ (B) The rate of glucose consumption by this cell will decrease sharply.





____ (C) The rate of oxygen consumption will increase.





____ (D) The citric acid cycle will speed up to compensate.

Answer 1

(A) False. Mitochondrial ATP synthesis will cease but to compensate, cells will accelerate the production of ATP by glycolysis, preventing ATP levels from dropping to zero.

(B) False. The acceleration of glycolysis will increase the rate of glucose consumption.

(C) False. The rate of oxygen consumption will decrease because electron transfer through respiratory chain is tightly coupled to ATP synthesis, blocking ATP synthase which blocks electron flow and oxygen consumption.

(D) False. The citric acid cycle is an oxidative pathway, producing NADH. When electron flow from NADH to O₂ is blocked, NADH accumulates, NAD⁺ is depleted and citric acid cycle slows for lack of an electron acceptor (NAD⁺).