Textbook Question
The final electron acceptor of the electron transport chain that functions in aerobic oxidative phosphorylation is
a. Oxygen.
b. Water.
c. NAD+.
d. Pyruvate.
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Ch. 9 - Cellular Respiration and Fermentation
Urry12th EditionCampbell BiologyISBN: 9785794169850
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Table of contents
- Ch. 1 - Evolution, the Themes of Biology, and Scientific Inquiry8
- Ch. 2 - The Chemical Context of Life8
- Ch. 3 - Water and Life6
- Ch. 4 - Carbon and the Molecular Diversity of Life9
- Ch. 5 - The Structure and Function of Large Biological Molecules9
- Ch. 6 - A Tour of the Cell6
- Ch. 7 - Membrane Structure and Function6
- Ch. 8 - An Introduction to Metabolism6
- Ch. 9 - Cellular Respiration and Fermentation10
- Ch. 10 - Photosynthesis7
- Ch. 11 - Cell Communication7
- Ch. 12 - The Cell Cycle11
- Ch. 13 - Meiosis and Sexual Life Cycles10
- Ch. 14 - Mendel and the Gene Idea14
- Ch, 15 - The Chromosomal Basis of Inheritance6
- Ch. 16 - The Molecular Basis of Inheritance9
- Ch. 17 - Gene Expression: From Gene to Protein9
- Ch. 18 - Regulation of Gene Expression10
- Ch. 19 - Viruses6
- Ch. 20 - DNA Tools and Biotechnology7
- Ch. 21 - Genomes and Their Evolution8
- Ch. 22 - Descent with Modification: A Darwininan View of Life6
- Ch. 23 - The Evolution of Populations5
- Ch. 24 - The Origin of Species6
- Ch. 25 - The History of Life on Earth8
- Ch. 26 - Phylogeny and the Tree of Life8
- Ch. 27 - Bacteria and Archaea6
- Ch. 28 - Protists7
- Ch. 29 - Plant Diversity I: How Plants Colonized Land7
- Ch. 30 - Plant Diversity II: The Evolution of Seed Plants6
- Ch. 31 - Fungi5
- Ch. 32 - An Overview of Animal Diversity4
- Ch. 33 - An introduction to Invertebrates6
- Ch. 34 - The Origin and Evolution of Vertebrates7
- Ch. 35 - Vascular Plant Structure, Growth, and Development10
- Ch. 36 - Resource Acquisition and Transport in Vascular Plants8
- Ch. 37 - Soil and Plant Nutrition11
- Ch. 38 - Angiosperm Reproduction and Biotechnology8
- Ch. 39 - Plant Responses to Internal and External Signals8
- Ch. 40 - Basic Principles of Animal Form and Function8
- Ch. 41 - Animal Nutrition7
- Ch. 42 - Circulation and Gas Exchange7
- Ch. 43 - The Immune System5
- Ch. 44 - Osmoregulation and Excretion6
- Ch. 45 - Hormones and the Endocrine System8
- Ch. 46 - Animal Reproduction9
- Ch. 47 - Animal Development8
- Ch. 48 - Neurons, Synapses, and Signaling6
- Ch. 49 - Nervous Systems8
- Ch. 50 - Sensory and Motor Mechanisms5
- Ch. 51 Animal Behavior6
- Ch. 52 - An Introduction to Ecology and the Biosphere7
- Ch. 53 - Population Ecology9
- Ch. 54 - Community Ecology9
- Ch. 55 - Ecosystems and Restoration Ecology8
- Ch. 56 - Conservation Biology and Global Change6
Chapter 9, Problem 6
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 guidance1
Understand the role of the electron transport chain (ETC) in mitochondria: The ETC is a series of protein complexes located in the inner mitochondrial membrane that facilitates the transfer of electrons from electron donors like NADH and FADH2 to oxygen, the final electron acceptor.
Recognize the process of chemiosmosis: As electrons move through the ETC, protons (H+) are pumped from the mitochondrial matrix into the intermembrane space, creating a proton gradient across the inner mitochondrial membrane.
Consider the effect of the proton gradient: The accumulation of protons in the intermembrane space lowers the pH there, while the matrix becomes more alkaline, indicating an increase in pH.
Understand the role of ATP synthase: ATP synthase is a protein complex that uses the energy from the proton gradient to synthesize ATP from ADP and inorganic phosphate. It does not pump protons by active transport; instead, it allows protons to flow back into the matrix, driving ATP synthesis.
Evaluate the options: Based on the understanding of the ETC and chemiosmosis, determine which option correctly describes a change that occurs when electrons flow along the electron transport chains of mitochondria.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Electron Transport Chain
The electron transport chain (ETC) is a series of protein complexes located in the inner mitochondrial membrane. It facilitates the transfer of electrons from electron donors like NADH and FADH2 to electron acceptors such as oxygen, through redox reactions. This process generates a proton gradient across the membrane, which is crucial for ATP synthesis.
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07:41
Electron Transport Chain
Proton Gradient and pH Change
As electrons move through the ETC, protons are pumped from the mitochondrial matrix into the intermembrane space, creating a proton gradient. This gradient results in a lower pH in the intermembrane space compared to the matrix. The flow of protons back into the matrix through ATP synthase drives the synthesis of ATP, increasing the matrix's pH.
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11:05pH Scale
Role of NAD+ in Cellular Respiration
NAD+ is a crucial coenzyme in cellular respiration, acting as an electron carrier. It is reduced to NADH when it accepts electrons during glycolysis and the Krebs cycle. In the ETC, NADH is oxidized back to NAD+, releasing electrons that contribute to the electron flow and proton gradient necessary for ATP production.
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03:39Introduction to Cellular Respiration
Related Practice
Textbook Question
In mitochondria, exergonic redox reactions
a. Are the source of energy driving prokaryotic ATP synthesis.
b. Provide the energy that establishes the proton gradient.
c. Reduce carbon atoms to carbon dioxide.
d. Are coupled via phosphorylated intermediates to endergonic processes.
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Textbook Question
What is the oxidizing agent in the following reaction?
Pyruvate + NADH + H+ ā Lactate + NAD+
a. Oxygen
b. NADH
c. Lactate
d. Pyruvate
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Textbook Question
Most CO2 from catabolism is released during
a. Glycolysis.
b. The citric acid cycle.
c. Lactate fermentation.
d. Electron transport.
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Textbook Question
Step 3 in Figure 9.8 is a major point of regulation of glycolysis. The enzyme phosphofructokinase is allosterically regulated by ATP and related molecules (see Concept 8.5). Considering the overall result of glycolysis, would you expect ATP to inhibit or stimulate activity of this enzyme? Explain.
(Hint: Make sure you consider the role of ATP as an allosteric regulator, not as a substrate of the enzyme.)
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Textbook Question
The proton pump shown in Figures 7.17 and 7.18 is a type of ATP synthase (see Figure 9.14). Compare the processes shown in the two figures, and say whether they are involved in active or passive transport (see Concepts 7.3 and 7.4).
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