Multiple Choice
Which metabolic pathway uses a proton motive force to generate ATP but does not require oxygen?
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8. Respiration
Chemiosmosis
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What is the energy source that powers ATP synthase during chemiosmosis?
A
A proton (H^+) gradient across the membrane
B
Hydrolysis of glucose
C
Direct transfer of electrons to ATP synthase
D
Oxygen binding to ATP synthase
Verified step by step guidance1
Understand the role of ATP synthase: ATP synthase is an enzyme that synthesizes ATP (adenosine triphosphate) from ADP (adenosine diphosphate) and inorganic phosphate during cellular respiration or photosynthesis.
Learn about chemiosmosis: Chemiosmosis refers to the movement of ions (specifically protons, H⁺) across a membrane, which generates an electrochemical gradient used to power ATP synthesis.
Identify the energy source: The energy source for ATP synthase during chemiosmosis is the proton (H⁺) gradient across the membrane. This gradient is established by the electron transport chain, which pumps protons into a specific compartment (e.g., the intermembrane space in mitochondria).
Explain the mechanism: Protons flow back across the membrane through ATP synthase due to the gradient. This movement, called proton motive force, drives the rotation of ATP synthase, enabling the enzyme to catalyze the formation of ATP.
Clarify why other options are incorrect: Hydrolysis of glucose provides energy earlier in cellular respiration but does not directly power ATP synthase. Direct transfer of electrons to ATP synthase does not occur; electrons are used in the electron transport chain. Oxygen is the final electron acceptor in the chain but does not bind to ATP synthase directly.
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