Multiple Choice
In cellular energy metabolism under aerobic conditions, which energy system produces the greatest amount of ATP per molecule of glucose?
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Review 4: Amino Acid Oxidation, Oxidative Phosphorylation, & Photophosphorylation
Oxidative Phosphorylation 1
Multiple Choice
In aerobic metabolism of one molecule of glucose in a typical mammalian cell, which pathway generates the greatest amount of ATP (directly or indirectly via NADH/FADH2)?
A
Glycolysis (substrate-level phosphorylation only)
B
Oxidative phosphorylation (electron transport chain coupled to chemiosmosis)
C
Pentose phosphate pathway
D
Citric acid cycle (substrate-level phosphorylation only)
Verified step by step guidance1
Step 1: Understand the main pathways involved in aerobic glucose metabolism: glycolysis, the citric acid cycle (Krebs cycle), and oxidative phosphorylation (electron transport chain coupled to chemiosmosis). Each pathway contributes differently to ATP production.
Step 2: Identify ATP production types in each pathway: glycolysis and the citric acid cycle produce ATP directly through substrate-level phosphorylation, while oxidative phosphorylation produces ATP indirectly by using NADH and FADH2 generated in earlier steps to drive ATP synthase.
Step 3: Recall that glycolysis produces a small net amount of ATP directly and generates NADH, which can be used later in oxidative phosphorylation to produce more ATP.
Step 4: Recognize that the citric acid cycle produces a small amount of ATP directly but generates multiple NADH and FADH2 molecules, which feed electrons into the electron transport chain for oxidative phosphorylation.
Step 5: Conclude that oxidative phosphorylation generates the greatest amount of ATP because it harnesses the high-energy electrons from NADH and FADH2 to produce ATP efficiently via chemiosmosis, far exceeding the ATP produced directly in glycolysis or the citric acid cycle.
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