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Ch. 9 - Cellular Respiration and Fermentation
Campbell - Campbell Biology 11th Edition
Urry11th EditionCampbell BiologyISBN: 9789357423311Non è quello che usi tu?Cambia libro di testo
Tutti i libri di testoUrry 11th EditionCh. 9 - Cellular Respiration and FermentationProblema 6
Capitolo 9, Problema 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.

Guida verificata passo dopo passo
1
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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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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11:05
pH 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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03:39
Introduction to Cellular Respiration
Pratica correlata
Domanda del libro di testo

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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Domanda del libro di testo

What is the oxidizing agent in the following reaction?

Pyruvate + NADH + H+ → Lactate + NAD+

a. Oxygen

b. NADH

c. Lactate

d. Pyruvate

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Domanda del libro di testo

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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Domanda del libro di testo

Most CO2 from catabolism is released during

a. Glycolysis.

b. The citric acid cycle.

c. Lactate fermentation.

d. Electron transport.

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Domanda del libro di testo

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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Domanda del libro di testo

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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