Question

What will happen to the citric acid cycle when a cell runs out of O₂, and why?

Group of answer choices

a) The citric acid cycle rate would decrease because the level of NAD⁺ would become too low.

b)The citric acid cycle rate would decrease because glycolysis would no longer produce pyruvate.

c) None of the other answers is correct.

D)The citric acid cycle would be unaffected, because it doesn’t use O₂.

E) The citric acid cycle rate would decrease because it must directly consume O₂ in order to keep going.

Answer 1

a) The citric acid cycle rate would decrease because the level of NAD+ would become low.

In the citric acid cycle, there are three steps where there is a conversion of NADH/H+ from NAD+ and the NADH/H+ produced in the reactions can donate their electrons in the next step of metabolism to yield the production of ATP. Now, the latter process requires constant support for the supply of oxygen. Now, if there is a decrease in the cellular oxygen level, then there would be an excess accumulation of NADH/H+ because it can't donate it's electrons in the electron transport chain thus shifting the equilibrium of the reaction to lower the level of NAD+. Therefore, the level of NAD+ would become very low when there is a drop in the oxygen level in the cell.