Question 1

Which of the following describes a correct and complete electron transfer pathway?

Accepted Answer

The correct pathway for electron transfer in the electron transport chain starts with NADH donating electrons to Complex I, then to Coenzyme Q (CoQ), followed by Complex III, cytochrome c (cyt c), and finally Complex IV. This sequence accurately reflects the flow of electrons from NADH through the main components of the electron transport chain to ultimately reduce oxygen to water.

Question 2

What is the approximate P/O ratio if the source of electrons for the electron transport chain is FADH₂?

Accepted Answer

The P/O ratio for FADH2 is approximately 1.5 because it enters the electron transport chain at complex II, bypassing complex I, and results in the pumping of fewer protons across the mitochondrial membrane compared to NADH.

Question 3

The presence of 10 copies of the c subunit of the F₀ complex of yeast ATP synthase allows for the synthesis of 1 ATP for every ______ proton(s)that are translocated across the inner mitochondrial membrane.

Accepted Answer

The presence of 10 copies of the c subunit in the yeast ATP synthase complex means that for each full rotation of the c-ring, 10 protons are translocated. Since one full rotation results in the synthesis of 3 ATP molecules, it takes 10/3 protons to synthesize 1 ATP, which is approximately 3.3 protons per ATP.

Question 4

__________ increases oxygen consumption while decreasing ATP synthesis, but ____________ decreases both oxygen consumption and ATP synthesis.

Accepted Answer

Rotenone and antimycin A both inhibit the electron transport chain, leading to an increase in oxygen consumption and a decrease in ATP synthesis. Valinomycin and nigericin are ionophores that affect ion gradients across the mitochondrial membrane but do not directly affect electron transport or ATP synthesis. Azide and cyanide bind to cytochrome oxidase, also leading to an increase in oxygen consumption and a decrease in ATP synthesis. 2,4-dinitrophenol (DNP) is an uncoupling agent that increases oxygen consumption without ATP synthesis. Oligomycin is an inhibitor of ATP synthase, leading to a decrease in both oxygen consumption and ATP synthesis. Therefore, DNP increases oxygen consumption while decreasing ATP synthesis, but oligomycin decreases both oxygen consumption and ATP synthesis.

Question 5

In addition to iron, what metal is found in certain cytochromes?

Accepted Answer

Copper is found in certain cytochromes, specifically in the copper-containing cytochrome c oxidase.

Question 6

The inhibition by an unknown inhibitor of electron transport was found to be removed by a large concentration of phenazine methosulfate. Since phenazine methosulfate is known to accept electrons from cytochrome b of complex III, which of the following is most similar to the unknown inhibitor?

Accepted Answer

Antimycin A is the correct answer because it specifically inhibits electron transport at complex III by binding to cytochrome c reductase, which is similar to the effect of the unknown inhibitor that can be alleviated by phenazine methosulfate, a compound known to accept electrons from cytochrome b of complex III.

Question 7

Which of the following acts as an uncoupler of the mitochondrial proton gradient due to its action as an ionophore?

Accepted Answer

The answer of Which of the following acts as an...

Question 8

Based on the following information, what is the $\Delta$G^$\circ$$\alpha$ for the oxidation of malate by NAD⁺? NAD⁺ + H⁺ + 2e^- NADH E^$\circ$' = -0.32 V Oxaloacetate + 2H⁺ + 2e^- malate E^$\circ$' = -0.17 V

Accepted Answer

The answer of Based on the following information, what is...

Question 9

Within the electron transport chain, complex _____ represents the entry point for electrons from NADH while complex _____ represents the entry point for electrons from FADH₂.

Accepted Answer

Complex I is the entry point for electrons from NADH, and Complex II is the entry point for electrons from FADH2.

Question 10

In the malate/aspartate shuttle, glutamate is converted to _________ in the mitochondria while aspartate is converted to ___________ in the cytosol.

Accepted Answer

In the malate/aspartate shuttle, glutamate is converted to $\alpha$-ketoglutarate in the mitochondria, and aspartate is converted to oxaloacetate in the cytosol.

Question 11

What is the approximate free energy for transporting a mole of protons from the matrix to the intermembrane space under normal conditions within the mitochondria?

Accepted Answer

The approximate free energy for transporting a mole of protons from the matrix to the intermembrane space under normal conditions within the mitochondria is +21 kJ/mol. This value is derived from the proton motive force across the mitochondrial membrane, which is a combination of the chemical gradient (pH difference) and the electrical gradient (voltage difference).

Question 12

Which of the following uses the energy of the proton gradient to drive transport of its substrates?

Accepted Answer

All the listed transport systems utilize the energy of the proton gradient to drive the transport of their substrates across the mitochondrial membrane, which is a fundamental aspect of cellular metabolism and energy production.

Question 13

If the following two reactions were coupled, what would be the oxidizing agent for the spontaneous reaction? NAD⁺ + H⁺ + 2e^- NADH E^$\circ$' = -0.32 V Acetaldehyde + 2H⁺ + 2e^- ethanol E^$\circ$' = -0.20 V

Accepted Answer

The answer of If the following two reactions were coupled,...

Question 14

Which amino acid is complexed to iron-sulfur clusters to enable them to associate with proteins?

Accepted Answer

It is cysteine that binds to iron-sulfur clusters through its thiol group (-SH) to enable their association with proteins. Cysteine is known for its ability to form disulfide bridges, which makes it a crucial amino acid for many proteins' proper folding and function. In the case of iron-sulfur clusters, cysteine's thiol group is essential for coordinating and stabilizing the iron ions in the cluster's structure.

Question 15

The oxidized form of coenzyme Q is considered a _______ while the reduced form is considered a _______.

Accepted Answer

The oxidized form of coenzyme Q is called a quinone while the reduced form is called a hydroquinone.

Question 16

Which of the following steps in the catalytic cycle of the F₁ component is the most energetically unfavorable?

Accepted Answer

The answer of Which of the following steps in the...

Question 17

Which of the following correctly describes what happens in the first stage of the Q cycle, considering that one cytochrome c is reduced in the process?

Accepted Answer

In the first stage of the Q cycle, one ubiquinol (QH2) molecule is oxidized to ubiquinone (Q), releasing two protons into the intermembrane space, while simultaneously, another Q molecule is reduced to semiquinone (Q.-), which is a partially reduced form of Q. This process contributes to the reduction of one cytochrome c molecule.

Question 18

Which of the following pathways takes place primarily within the inner mitochondrial membrane?

Accepted Answer

The electron transport chain takes place primarily within the inner mitochondrial membrane. The other pathways listed occur in different parts of the cell or in different parts of the mitochondria.

Question 19

Rotation of the ____ subunit causes the _____ subunit to change from tight conformation where ATP is produced to open conformation where ATP is released.

Accepted Answer

The rotating subunit in the F1 portion of ATP synthase is the gamma (γ) subunit. When this subunit rotates, it causes a conformational change in the adjacent β subunit, which shifts from a tight conformation that produces ATP to an open conformation that releases ATP. The α and δ subunits do not play a role in this process, and the ε subunit is not listed as an option.

Question 20

Which of the following correctly indicates the number of protons pumped into the intermembrane space at each complex of electron transport for each FADH₂ that is oxidized by the electron transport pathway?

Accepted Answer

FADH2 donates electrons to Complex II, which does not pump protons. Complex III pumps 4 protons, and Complex IV pumps 2 protons into the intermembrane space.

Quiz 15: Electron Transport, Oxidative Phosphorylation, and Oxygen Metabolism

Which of the following describes a correct and complete electron transfer pathway?

What is the approximate P/O ratio if the source of electrons for the electron transport chain is FADH₂?

The presence of 10 copies of the c subunit of the F₀ complex of yeast ATP synthase allows for the synthesis of 1 ATP for every ______ proton(s) that are translocated across the inner mitochondrial membrane.

increases oxygen consumption while decreasing ATP synthesis, but __ decreases both oxygen consumption and ATP synthesis.

In addition to iron, what metal is found in certain cytochromes?

The inhibition by an unknown inhibitor of electron transport was found to be removed by a large concentration of phenazine methosulfate. Since phenazine methosulfate is known to accept electrons from cytochrome b of complex III, which of the following is most similar to the unknown inhibitor?

Which of the following acts as an uncoupler of the mitochondrial proton gradient due to its action as an ionophore?

Within the electron transport chain, complex _ represents the entry point for electrons from NADH while complex _ represents the entry point for electrons from FADH₂.

In the malate/aspartate shuttle, glutamate is converted to _ in the mitochondria while aspartate is converted to ___ in the cytosol.

What is the approximate free energy for transporting a mole of protons from the matrix to the intermembrane space under normal conditions within the mitochondria?

Which of the following uses the energy of the proton gradient to drive transport of its substrates?

Which amino acid is complexed to iron-sulfur clusters to enable them to associate with proteins?

The oxidized form of coenzyme Q is considered a _ while the reduced form is considered a _.

Which of the following steps in the catalytic cycle of the F₁ component is the most energetically unfavorable?

Which of the following correctly describes what happens in the first stage of the Q cycle, considering that one cytochrome c is reduced in the process?

Which of the following pathways takes place primarily within the inner mitochondrial membrane?

Rotation of the subunit causes the _ subunit to change from tight conformation where ATP is produced to open conformation where ATP is released.

Which of the following correctly indicates the number of protons pumped into the intermembrane space at each complex of electron transport for each FADH₂ that is oxidized by the electron transport pathway?

Quiz 15: Electron Transport, Oxidative Phosphorylation, and Oxygen Metabolism

Which of the following describes a correct and complete electron transfer pathway?

What is the approximate P/O ratio if the source of electrons for the electron transport chain is FADH2?

The presence of 10 copies of the c subunit of the F0 complex of yeast ATP synthase allows for the synthesis of 1 ATP for every ______ proton(s) that are translocated across the inner mitochondrial membrane.

__________ increases oxygen consumption while decreasing ATP synthesis, but ____________ decreases both oxygen consumption and ATP synthesis.

In addition to iron, what metal is found in certain cytochromes?

The inhibition by an unknown inhibitor of electron transport was found to be removed by a large concentration of phenazine methosulfate. Since phenazine methosulfate is known to accept electrons from cytochrome b of complex III, which of the following is most similar to the unknown inhibitor?

Which of the following acts as an uncoupler of the mitochondrial proton gradient due to its action as an ionophore?

Based on the following information, what is the Δ\DeltaΔ G ∘\circ∘ α\alphaα for the oxidation of malate by NAD+? NAD+ + H+ + 2e- NADH E ∘\circ∘ ' = -0.32 V Oxaloacetate + 2H+ + 2e- malate E ∘\circ∘ ' = -0.17 V

Within the electron transport chain, complex _____ represents the entry point for electrons from NADH while complex _____ represents the entry point for electrons from FADH2.

In the malate/aspartate shuttle, glutamate is converted to _________ in the mitochondria while aspartate is converted to ___________ in the cytosol.

What is the approximate free energy for transporting a mole of protons from the matrix to the intermembrane space under normal conditions within the mitochondria?

Which of the following uses the energy of the proton gradient to drive transport of its substrates?

If the following two reactions were coupled, what would be the oxidizing agent for the spontaneous reaction? NAD+ + H+ + 2e- NADH E ∘\circ∘ ' = -0.32 V Acetaldehyde + 2H+ + 2e- ethanol E ∘\circ∘ ' = -0.20 V

Which amino acid is complexed to iron-sulfur clusters to enable them to associate with proteins?

The oxidized form of coenzyme Q is considered a _______ while the reduced form is considered a _______.

Which of the following steps in the catalytic cycle of the F1 component is the most energetically unfavorable?

Which of the following correctly describes what happens in the first stage of the Q cycle, considering that one cytochrome c is reduced in the process?

Which of the following pathways takes place primarily within the inner mitochondrial membrane?

Rotation of the ____ subunit causes the _____ subunit to change from tight conformation where ATP is produced to open conformation where ATP is released.

Which of the following correctly indicates the number of protons pumped into the intermembrane space at each complex of electron transport for each FADH2 that is oxidized by the electron transport pathway?

What is the approximate P/O ratio if the source of electrons for the electron transport chain is FADH₂?

The presence of 10 copies of the c subunit of the F₀ complex of yeast ATP synthase allows for the synthesis of 1 ATP for every ______ proton(s) that are translocated across the inner mitochondrial membrane.

increases oxygen consumption while decreasing ATP synthesis, but __ decreases both oxygen consumption and ATP synthesis.

Within the electron transport chain, complex _ represents the entry point for electrons from NADH while complex _ represents the entry point for electrons from FADH₂.

In the malate/aspartate shuttle, glutamate is converted to _ in the mitochondria while aspartate is converted to ___ in the cytosol.

The oxidized form of coenzyme Q is considered a _ while the reduced form is considered a _.

Which of the following steps in the catalytic cycle of the F₁ component is the most energetically unfavorable?

Rotation of the subunit causes the _ subunit to change from tight conformation where ATP is produced to open conformation where ATP is released.

Which of the following correctly indicates the number of protons pumped into the intermembrane space at each complex of electron transport for each FADH₂ that is oxidized by the electron transport pathway?