Import Question JSON

The chemiosmotic theory, proposed by Peter Mitchell in 1961, explains how the movement of protons across a membrane can generate ATP. According to this theory, ATP synthesis is driven by a proton gradient that is established across a membrane, such as the thylakoid membrane in chloroplasts or the inner mitochondrial membrane. The energy to establish this gradient is derived from electron transport chains that transfer electrons from electron donors to electron acceptors, such as NADH or FADH₂. As the electrons move through the electron transport chain, protons are pumped from the matrix or stroma to the intermembrane space or thylakoid lumen, creating a proton gradient across the membrane. The gradient represents a difference in the concentration of protons on either side of the membrane and a difference in the electrical charge, which creates an electrochemical gradient. The potential energy stored in this gradient is then used to synthesize ATP through the action of ATP synthase, which is a membrane-bound enzyme that uses the flow of protons down the gradient to drive the synthesis of ATP from ADP and inorganic phosphate. Options 1, 2, and 4 are incorrect because they do not reflect the mechanism proposed by the chemiosmotic theory. While membrane potential and ion accumulation are involved in various cellular processes, they do not play a role in the ATP synthesis mechanism proposed by the chemiosmotic theory.