Multiple Choice
In cellular respiration, which process produces the greatest amount of ATP per molecule of glucose under typical aerobic conditions?
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Review 4: Amino Acid Oxidation, Oxidative Phosphorylation, & Photophosphorylation
Oxidative Phosphorylation 1
Multiple Choice
In oxidative phosphorylation, which of the following electron donors yields the greatest amount of ATP per pair of electrons transferred to the electron transport chain under typical mitochondrial conditions?
A
NADH donating electrons to Complex I
B
Cytochrome donating electrons to Complex IV
C
FADH donating electrons via Complex II (succinate dehydrogenase)
D
Ubiquinol (QH) donating electrons directly to Complex III
Verified step by step guidance1
Identify the entry points of each electron donor into the electron transport chain (ETC): NADH donates electrons to Complex I, FADH2 donates electrons to Complex II, ubiquinol (QH2) donates electrons to Complex III, and cytochrome c donates electrons to Complex IV.
Understand that the number of protons pumped across the inner mitochondrial membrane correlates with the amount of ATP synthesized, and this proton pumping depends on which complexes the electrons pass through.
Recall that electrons entering at Complex I (NADH) pass through Complexes I, III, and IV, resulting in the pumping of more protons compared to electrons entering at Complex II (FADH2) or directly at Complex III or IV.
Recognize that cytochrome c donates electrons at Complex IV, which is the last step in the chain and does not contribute to proton pumping upstream, thus yielding less ATP per electron pair.
Conclude that since NADH donates electrons at Complex I, which leads to the highest proton gradient formation, it yields the greatest amount of ATP per pair of electrons transferred under typical mitochondrial conditions.
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