The direct energy source that drives ATP synthesis during respiratory oxidative phosphorylation in eukaryotic cells is
A)oxidation of glucose to CO₂ and water.
B)the thermodynamically favourable flow of electrons from NADH to the mitochondrial electron transport carriers.
C)the final transfer of electrons to oxygen.
D)the proton-motive force across the inner mitochondrial membrane.
E)the thermodynamically favourable transfer of phosphate from glycolysis and the citric acid cycle intermediate molecules of ADP.

Question

Quizplus · Accepted Answer

The direct energy source that drives ATP synthesis during respiratory oxidative phosphorylation in eukaryotic cells is the proton-motive force across the inner mitochondrial membrane. This force is generated by the transport of protons across the inner membrane, from the intermembrane space to the matrix, by complexes I, III, and IV of the electron transport chain. This generates a gradient of protons, or a difference in proton concentration and charge, across the membrane. This gradient is then used by ATP synthase to phosphorylate ADP to form ATP. Therefore, option D, the proton motive force across the inner mitochondrial membrane, is the correct answer.

The Direct Energy Source That Drives ATP Synthesis During Respiratory