Question

Production of ATP by oxidative phosphorylation is driven by energy from

• A. Coenzyme A
• B. $NAD{H}_2$
• C. Pyruvic acid
• D. Movement of protons from inner mitochondrial membrane to the cytoplasm

Answer 1

Answer: (D)

Movement of protons from inner mitochondrial membrane to the cytoplasm

Electrons from NADH and FADH2 pass through electron transport chain in the inner membrane. Electron flow is accompanied by proton transfer across the membrane and establishes a chemical gradient and an electrical gradient. The impermeable inner mitochondrial membrane does not allow transport of protons; protons re-enter the matrix only through proton-specific channels of ATP synthetase. The proton-motive force drives protons back into the matrix and provides energy for ATP synthesis the F1 complex. The correct answer is D.