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Multiple Choice
How does the electron transport chain participate in generating ATP during cellular respiration?
A
By breaking down glucose into pyruvate, releasing energy for ATP production.
B
By creating a proton gradient across the inner mitochondrial membrane, which drives ATP synthesis via ATP synthase.
C
By directly phosphorylating ADP to form ATP without the involvement of a proton gradient.
D
By converting ATP into ADP and inorganic phosphate to release energy.
Verified step by step guidance
1
Understand the role of the electron transport chain (ETC) in cellular respiration: The ETC is the final stage of aerobic respiration, located in the inner mitochondrial membrane. Its primary function is to transfer electrons from electron carriers (NADH and FADH2) to oxygen, the final electron acceptor.
Recognize how the ETC creates a proton gradient: As electrons move through the ETC, energy is released and used to pump protons (H⁺ ions) from the mitochondrial matrix into the intermembrane space. This creates a high concentration of protons in the intermembrane space compared to the matrix.
Learn how the proton gradient drives ATP synthesis: The proton gradient represents potential energy. Protons flow back into the matrix through ATP synthase, a protein complex embedded in the inner mitochondrial membrane. This flow, known as chemiosmosis, provides the energy needed for ATP synthase to phosphorylate ADP into ATP.
Clarify why the ETC does not directly phosphorylate ADP: The ETC itself does not directly produce ATP. Instead, it creates the conditions (proton gradient) necessary for ATP synthase to perform this function.
Understand the importance of oxygen: Oxygen acts as the final electron acceptor in the ETC. Without oxygen, the ETC cannot function, and the proton gradient cannot be maintained, halting ATP production via oxidative phosphorylation.