Question

Chemiosmosis, the generation of a proton gradient across the inner mitochondrial membrane, is a crucial requirement for the synthesis of ATP in cellular respiration.

How does the cell power the movement of protons up its gradient?

• A. A transporter on the outer membrane allows the diffusion of protons from the cytoplasm into the inner membrane space.
• B. ATP synthase powers the movement of protons across the membrane while simultaneously generating ATP.
• C. Electrons are transported into the inner membrane space drawing in protons due to electrostatic attraction.
• D. Complexes of the electron transport chain undergo redox reactions that, in turn, generates the energy to pass protons up its gradient.

Answer 1

Answer: (D)

Complexes of the electron transport chain undergo redox reactions that, in turn, generates the energy to pass protons up its gradient.

The protein complexes of the electron transport chain accept and pass on e${}^{-}$ to the next acceptor, that is they undergo redox reactions, during this process the e${}^{-}$ moves down its energy gradient releasing free energy at each transfer, also called as EMF which drives the movement of protons up their concentration gradient into the matrix of mitochondria

So, the correct answer is 'Complexes of the electron transport chain undergo redox reactions that, in turn, generates the energy to pass protons up its gradient'