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Ch. 9 - Cellular Respiration and Fermentation
Freeman - Biological Science 8th Edition
Freeman8th EditionBiological ScienceISBN: 9780138276263Not the one you use?Change textbook
Chapter 9, Problem 2

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.

Verified step by step guidance
1
Understand the chemiosmotic hypothesis: It is a scientific theory that explains how ATP is generated in the mitochondria during cellular respiration.
Recognize the role of the electron transport chain: The electron transport chain creates a proton gradient across the inner mitochondrial membrane.
Identify the proton-motive force: The proton gradient generates a proton-motive force, which is essential for ATP synthesis.
Connect the proton-motive force to ATP synthesis: ATP synthase uses the energy from the proton-motive force to convert ADP and inorganic phosphate into ATP.
Evaluate the options: Based on the chemiosmotic hypothesis, identify the correct statement that describes ATP generation using the proton-motive force produced by the electron transport chain.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Chemiosmotic Hypothesis

The chemiosmotic hypothesis, proposed by Peter Mitchell, explains how ATP is generated in mitochondria. It suggests that the electron transport chain creates a proton gradient across the inner mitochondrial membrane. This gradient, known as the proton-motive force, drives the synthesis of ATP as protons flow back into the mitochondrial matrix through ATP synthase.
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Electron Transport Chain

The electron transport chain (ETC) is a series of protein complexes located in the inner mitochondrial membrane. It transfers electrons from electron donors like NADH and FADH2 to oxygen, the final electron acceptor. This process releases energy, which is used to pump protons across the membrane, creating a proton gradient essential for ATP production.
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Electron Transport Chain

Proton-Motive Force

The proton-motive force is the energy stored in the form of a proton gradient across a membrane. In mitochondria, it is generated by the electron transport chain as protons are pumped from the mitochondrial matrix to the intermembrane space. This force drives protons back into the matrix through ATP synthase, facilitating the conversion of ADP and inorganic phosphate into ATP.
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