What does the chemiosmotic hypothesis claim? a. ATP is generated using phosphates taken from intermediates in the electron transport chain. b. ATP is generated using a phosphate gradient produced by glycolysis and the citric acid cycle. c. ATP is generated using a proton-motive force that is produced by the electron transport chain. d. Water is generated using electrons taken from NADH and FADH2 and transported through the electron transport chain.

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1. The chemiosmotic hypothesis is a theory that explains how ATP is produced in the mitochondria during the process of oxidative phosphorylation. It was proposed by Peter Mitchell in 1961.
2. According to this hypothesis, the electron transport chain in the inner mitochondrial membrane pumps protons (H+) from the mitochondrial matrix to the intermembrane space, creating a proton gradient.
3. This proton gradient, also known as a proton-motive force, is then used to drive the synthesis of ATP as protons flow back into the mitochondrial matrix through the ATP synthase enzyme.
4. Therefore, the correct answer is c. ATP is generated using a proton-motive force that is produced by the electron transport chain.
5. The other options (a, b, and d) are incorrect because they do not accurately describe the process of ATP synthesis according to the chemiosmotic hypothesis.

Key Concepts

Chemiosmotic Hypothesis

The chemiosmotic hypothesis, proposed by Peter Mitchell, explains how ATP is synthesized in mitochondria and chloroplasts. It posits that the energy from electron transport chains is used to pump protons across a membrane, creating a proton gradient. This gradient generates a proton-motive force, which drives ATP synthesis as protons flow back through ATP synthase.

Proton-Motive Force

Proton-motive force refers to the potential energy stored in the form of a proton gradient across a membrane. This gradient is established by the active transport of protons during electron transport. The energy released when protons flow back into the mitochondrial matrix through ATP synthase is harnessed to convert ADP and inorganic phosphate into ATP.

Electron Transport Chain

The electron transport chain (ETC) is a series of protein complexes located in the inner mitochondrial membrane that facilitate the transfer of electrons from electron donors like NADH and FADH2 to electron acceptors. As electrons move through the chain, energy is released, which is used to pump protons into the intermembrane space, contributing to the proton gradient essential for ATP production.