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Ch. 6 How Cells Harvest Chemical Energy
Taylor - Campbell Biology: Concepts & Connections 10th Edition
Taylor, Simon, Dickey, Hogan10th EditionCampbell Biology: Concepts & ConnectionsISBN: 9780136538783Not the one you use?Change textbook
All textbooksTaylor, Simon, Dickey, Hogan 10th EditionCh. 6 How Cells Harvest Chemical EnergyProblem 5
Chapter 6, Problem 5

Which of the following is the most immediate source of energy for making most of the ATP in your cells?
a. The transfer of from intermediate substrates to ADP
b. The movement of H⁺ across a membrane down its concentration gradient
c. The splitting of glucose into two molecules of pyruvate
d. Electrons moving through the electron transport chain

Verified step by step guidance
1
Understand the context of ATP production in cells: ATP is primarily synthesized during cellular respiration, which includes glycolysis, the citric acid cycle, and oxidative phosphorylation.
Recall that oxidative phosphorylation is the stage where most ATP is produced. This process involves the electron transport chain and chemiosmosis.
Recognize that the electron transport chain creates a proton (H⁺) gradient across the inner mitochondrial membrane by pumping H⁺ ions into the intermembrane space.
Understand that the movement of H⁺ ions back across the membrane, down their concentration gradient, through ATP synthase drives the synthesis of ATP from ADP and inorganic phosphate (Pi).
Match the correct option to the explanation: The movement of H⁺ ions across a membrane down their concentration gradient (option b) is the most immediate source of energy for making most of the ATP in cells.

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Key Concepts

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

ATP Synthesis

ATP (adenosine triphosphate) is the primary energy carrier in cells. It is produced through various metabolic pathways, with the most significant being oxidative phosphorylation, where ATP is generated as electrons are transferred through the electron transport chain, ultimately leading to the phosphorylation of ADP.
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ATP

Proton Gradient

A proton gradient is created when protons (H+) are pumped across a membrane, establishing a difference in concentration. This gradient is crucial for ATP synthesis, as protons flow back across the membrane through ATP synthase, driving the conversion of ADP to ATP, a process known as chemiosmosis.
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Glycolysis

Glycolysis is the metabolic pathway that breaks down glucose into pyruvate, producing a small amount of ATP and NADH in the process. While it is an important step in cellular respiration, it is not the most immediate source of ATP compared to the processes that utilize the proton gradient.
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Related Practice
Textbook Question

A biochemist wanted to study how various substances were used in cellular respiration. In one experiment, she allowed a mouse to breathe air containing O₂ 'labeled' by a particular isotope. In the mouse, the labeled oxygen first showed up in

a. ATP

b. NADH

c. CO₂

d. H₂O

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Textbook Question

In glycolysis, ________ is oxidized and ________ is reduced.

a. NAD+ ... glucose

b. Glucose ... oxygen

c. ATP ... ADP

d. Glucose ... NAD+

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Textbook Question

Most of the CO₂ from cellular respiration is released during

a. Stage 1: Glycolysis

b. Stage 2: Pyruvate oxidation

c. Stage 2: The citric acid cycle

d. Stage 3: Oxidative phosphorylation

3025
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Textbook Question

Which of the following is a distinction between cellular respiration and fermentation?

a. The transfer of from intermediate substrates to ADP

b. The movement of H+ across a membrane down its concentration gradient

c. The splitting of glucose into two molecules of pyruvate

d. Electrons moving through the electron transport chain

1287
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Textbook Question

The poison cyanide binds to an electron carrier within the electron transport chain and blocks the movement of electrons. When this happens, glycolysis and the citric acid cycle soon grind to a halt as well. Why do you think these other two stages of cellular respiration stop? (Explain your answer.)

a. They run out of ATP

b. Unused O₂ interferes with cellular respiration

c. They run out of NAD+ and FAD

d. Electrons are no longer available

6154
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Textbook Question

In which of the following is the first molecule becoming reduced to the second molecule?

a. Pyruvate → acetylCoA

b. Pyruvate → lactate

c. Glucose → pyruvate

d. NADH + H+ →NAD+ + 2H

1695
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