Question

Maintenance of the proton motive force requires that:

a. the inner mitochondrial membrane is impermeable to electrons.
b. the inner mitochondrial membrane is impermeable to protons.
c. the plasma membrane is impermeable to protons.
d. protons remain lipid soluble.
e. the mitochondrial matrix supplies electrons for passage down the electron transport chain.

Answer 1

To maintain the proton motive force, the inner mitochondrial membrane must be impermeable to protons, which prevents them from dissipating the established gradient and allows ATP synthesis via ATP synthase.

Step-by-step explanation:

The maintenance of the proton motive force is crucial for ATP synthesis in the mitochondria through a process called oxidative phosphorylation. The correct option to maintain the proton motive force requires that b. the inner mitochondrial membrane is impermeable to protons. This impermeability prevents protons from simply diffusing back into the mitochondrial matrix, thereby preserving the proton gradient established by the electron transport chain (ETC). Protons can only re-enter the matrix through the ATP synthase complex, which uses the energy from the proton gradient to synthesize ATP.

The other options are not correct because a) electrons must be carried through the ETC, not the membrane, c) the plasma membrane's permeability to protons is not related to the mitochondrial function, d) protons are not lipid-soluble, and e) the mitochondrial matrix does not supply electrons, but the electrons are provided by reduced cofactors NADH and FADH2.