Table of contents

1. Introduction to Anatomy & Physiology5h 43m
2. Cell Chemistry & Cell Components12h 36m
3. Energy & Cell Processes10h 6m
4. Tissues & Histology10h 3m
5. Integumentary System2h 20m
6. Bones & Skeletal Tissue2h 16m
7. The Skeletal System2h 35m
8. Joints2h 17m
9. Muscle Tissue2h 33m
10. Muscles1h 11m
11. Nervous Tissue and Nervous System1h 35m
12. The Central Nervous System1h 6m
- Introduction to the Central Nervous System
  18m
- The Cerebrum
  48m
13. The Peripheral Nervous System1h 26m
14. The Autonomic Nervous System1h 38m
15. The Special Senses2h 41m
16. The Endocrine System2h 48m
17. The Blood3h 22m
18. The Heart3h 42m
19. The Blood Vessels3h 35m
20. The Lymphatic System3h 16m
21. The Immune System14h 37m
22. The Respiratory System3h 20m
23. The Digestive System2h 5m
24. Metabolism and Nutrition4h 0m
25. The Urinary System2h 39m
26. Fluid and Electrolyte Balance, Acid Base Balance37m
27. The Reproductive System2h 5m
28. Human Development1h 21m
29. Heredity3h 32m

3. Energy & Cell Processes

Electron Transport Chain

Anatomy & Physiology

3. Energy & Cell Processes

Electron Transport Chain

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Problem 6

Textbook Question

When electrons flow along the electron transport chains of mitochondria, which of the following changes occurs?a. The pH of the matrix increases.b. ATP synthase pumps protons by active transport.c. The electrons gain free energy.d. NAD+ is oxidized.

Verified step by step guidance

Identify the role of the electron transport chain (ETC) in mitochondria, which is to transfer electrons from electron donors to electron acceptors via redox reactions.

Understand that as electrons move through the ETC, they release energy, which is used to pump protons (H+) from the mitochondrial matrix to the intermembrane space, creating a proton gradient.

Recognize that the movement of protons into the intermembrane space decreases the pH there, while the pH of the matrix increases as protons are pumped out.

Recall that ATP synthase uses the proton gradient to synthesize ATP from ADP and inorganic phosphate, but it does not pump protons by active transport; instead, it allows protons to flow back into the matrix, driving ATP synthesis.

Note that NAD+ is reduced to NADH during earlier stages of cellular respiration, and in the ETC, NADH is oxidized back to NAD+ as it donates electrons.

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Key Concepts

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

Electron Transport Chain (ETC)

The electron transport chain 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. This process generates a proton gradient across the membrane, which is essential for ATP production through oxidative phosphorylation.

Proton Gradient and pH Changes

As electrons move through the ETC, protons (H+) are pumped from the mitochondrial matrix into the intermembrane space, creating a proton gradient. This gradient leads to a decrease in pH in the intermembrane space and an increase in pH in the matrix, which is crucial for ATP synthesis as protons flow back into the matrix through ATP synthase.

ATP Synthase Function

ATP synthase is an enzyme that synthesizes ATP from ADP and inorganic phosphate, utilizing the energy from the proton gradient established by the ETC. It operates through a process called chemiosmosis, where protons flow down their concentration gradient through ATP synthase, driving the conversion of ADP to ATP.