Question

Q36). In the final stage of the oxidation of food molecules, a gradient of protons is formed across the inner mitochondrial membrane, which is normally impermeable to protons. If cells were exposed to an agent that causes the membrane to become freely permeable to protons, which of the following effects would you expect to observe?

A) The ratio of ATP to ADP in the cytoplasm would fall.
B) NADH would build up.
C) Carbon dioxide production would cease.
D) The consumption of oxygen would fall.

Answer 1

If the inner mitochondrial membrane becomes permeable to protons, the established proton gradient is disrupted, stopping ATP production and causing the ratio of ATP to ADP in the cytoplasm to fall.

Step-by-step explanation:

When cells are exposed to an agent that makes the inner mitochondrial membrane permeable to protons, the established proton gradient is dissipated. As the gradient is crucial for ATP synthesis, it results in the immediate stop of ATP production because protons would flow back into the mitochondrial matrix without generating ATP. Consequently, the ratio of ATP to ADP in the cytoplasm would fall (Option A), as ATP synthesis relies on the potential energy provided by the proton gradient to add a phosphate to ADP, forming ATP. Hence, the agent would effectively uncouple the electron transport chain from oxidative phosphorylation.