Question 1

Which statement is FALSE regarding 2,4-dinitrophenol?

Accepted Answer

2,4-dinitrophenol does not require a specific transporter to enter mitochondria, as it can freely diffuse across the mitochondrial membrane.

Question 2

Which statement explains why the [ATP]/[ADP][P_i] ratio is relatively stable in a cell?

Accepted Answer

The relatively stable [ATP]/[ADP] ratio in a cell is maintained by a balance between ATP consumption and ATP synthesis by ATP synthase. This ensures that the cell has enough energy to carry out its functions while preventing an excessive buildup of ATP that could potentially disrupt cellular processes.

Question 3

Which protein is NOT portion encoded in human mitochondrial DNA?

Accepted Answer

Cytochrome c is a small heme protein found loosely associated with the inner membrane of the mitochondrion. It is encoded by nuclear DNA, not mitochondrial DNA.

Question 4

What will NOT occur when 2,4-dinitrophenol (an uncoupler of oxidative phosphorylation) is added to actively respiring mitochondria?

Accepted Answer

2,4-Dinitrophenol (DNP) disrupts the proton gradient across the mitochondrial membrane, which decreases the efficiency of ATP synthesis (lowering the P:O ratio), not increasing it. The other options (B, C, D, E) are effects of DNP's action as an uncoupler, which increases the rate of electron transport and associated processes but decreases the efficiency of ATP production.

Question 5

In some organisms, an alternative oxidase will accept electrons from ubiquinol and reduce oxygen to water with no associated proton translocation. What would be a consequence of having this oxidase active?

Accepted Answer

The P:O ratio is the ratio of ATP molecules synthesized to oxygen molecules consumed. Since the alternative oxidase reduces oxygen without pumping protons, ATP synthesis would decrease in proportion to the oxygen consumed, resulting in a decreased P:O ratio.

Question 6

What effect will increasing the number of c subunits in ATP synthase have on the P:O ratio?

Accepted Answer

The P:O ratio, which indicates the number of ATP molecules synthesized per oxygen atom reduced, is influenced by the efficiency of ATP synthase. Increasing the number of c subunits in ATP synthase makes the enzyme less efficient, as more protons are required to make one rotation and synthesize ATP. This inefficiency leads to a decrease in the P:O ratio for both NADH and FADH2, as more protons (and thus more electron transport) are needed per ATP synthesized.

Question 7

Which statement is TRUE regarding the gamma ($\gamma$) subunit of ATP synthase?

Accepted Answer

The gamma subunit of ATP synthase is primarily composed of alpha-helical structures, which are part of its regular secondary structure.

Question 8

Which statement does NOT describe characteristics of the protein inhibitor IF₁?

Accepted Answer

The statement "This protein will bind to the F_O portion of ATP synthase" is the only statement that describes a specific characteristic of the inhibitor, while the other statements describe general characteristics of protein inhibitors or specific characteristics that are not unique to IF₁.

Question 9

Which list shows the proteins in the CORRECT order from highest to lowest reduction potential?

Accepted Answer

The correct order from highest to lowest reduction potential among the given proteins is ETF:Q oxidoreductase > ETF > acyl-CoA dehydrogenase. This sequence reflects the flow of electrons in the mitochondrial electron transport chain, where molecules with higher reduction potentials accept electrons from those with lower potentials.

Question 10

Which statement is TRUE regarding the reduction potential of mitochondrial glycerol 3 phosphate dehydrogenase?

Accepted Answer

The reduction potential of mitochondrial glycerol 3 phosphate dehydrogenase is higher than that of NADH but lower than that of Complex III.

Question 11

Which complex in the electron-transport chain contains copper ions?

Accepted Answer

Complex IV, also known as cytochrome c oxidase, contains copper ions. Specifically, there are two copper ions, labeled CuA and CuB, which are involved in transferring electrons and ultimately reducing oxygen to form water.

Question 12

Cytochrome P-450 gets its name from what characteristic?

Accepted Answer

Cytochrome P-450 is named after its characteristic absorption of light at a wavelength of 450 nm.

Question 13

What mechanism accounts for mitochondrial inheritance in sexual reproduction in animals?

Accepted Answer

The answer of What mechanism accounts for mitochondrial inheritance in...

Question 14

Which step is NOT part of the proton-translocation process in ATP synthase?

Accepted Answer

The correct steps in the proton-translocation process of ATP synthase involve specific interactions between subunits and the movement of protons, but reversible protonation and deprotonation of an arginine in the a subunit is not part of this mechanism.

Question 15

In which pairing are both transporters symports?

Accepted Answer

Phosphate translocase and pyruvate translocase are both symporters, as they transport their respective substrates along with protons (H+) across the mitochondrial membrane.

Question 16

Which statement is FALSE regarding ATP synthase?

Accepted Answer

The answer of Which statement is FALSE regarding ATP synthase?
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Question 17

What is the P:O ratio for electrons entering the electron-transport chain that originate from reoxidation of acyl-CoA dehydrogenase?

Accepted Answer

The P:O ratio for electrons entering the electron-transport chain from the reoxidation of acyl-CoA dehydrogenase is approximately the same as the P:O ratio for Complex II reoxidation. This is because the electrons from acyl-CoA dehydrogenase enter the electron transport chain at a point similar to where FADH2 (which is reoxidized by Complex II) enters, thus yielding a similar number of ATP molecules per oxygen atom reduced.

Question 18

What compound is a product of the reaction involving the superoxide free radical catalyzed by superoxide dismutase?

Accepted Answer

Superoxide dismutase catalyzes the conversion of superoxide free radicals into hydrogen peroxide and molecular oxygen.

Question 19

What is the role of cytochrome c in apoptosis?

Accepted Answer

Cytochrome c binds with Apaf-1 (apoptotic protease activating factor-1) and procaspase-9 to form the apoptosome complex which activates caspase cascades leading to apoptosis.

Question 20

During the operation of the malate-aspartate shuttle, what process does NOT occur?

Accepted Answer

The answer of During the operation of the malate-aspartate shuttle,...

Quiz 19: Oxidative Phosphorylation and Photophosphorylation

Which statement is FALSE regarding 2,4-dinitrophenol?

Which statement explains why the [ATP]/[ADP][P_i] ratio is relatively stable in a cell?

Which protein is NOT portion encoded in human mitochondrial DNA?

What will NOT occur when 2,4-dinitrophenol (an uncoupler of oxidative phosphorylation) is added to actively respiring mitochondria?

In some organisms, an alternative oxidase will accept electrons from ubiquinol and reduce oxygen to water with no associated proton translocation. What would be a consequence of having this oxidase active?

What effect will increasing the number of c subunits in ATP synthase have on the P:O ratio?

Which statement is TRUE regarding the gamma ( $\gamma$ ) subunit of ATP synthase?

Which statement does NOT describe characteristics of the protein inhibitor IF₁?

Which list shows the proteins in the CORRECT order from highest to lowest reduction potential?

Which statement is TRUE regarding the reduction potential of mitochondrial glycerol 3 phosphate dehydrogenase?

Which complex in the electron-transport chain contains copper ions?

Cytochrome P-450 gets its name from what characteristic?

What mechanism accounts for mitochondrial inheritance in sexual reproduction in animals?

Which step is NOT part of the proton-translocation process in ATP synthase?

In which pairing are both transporters symports?

Which statement is FALSE regarding ATP synthase?

What is the P:O ratio for electrons entering the electron-transport chain that originate from reoxidation of acyl-CoA dehydrogenase?

What compound is a product of the reaction involving the superoxide free radical catalyzed by superoxide dismutase?

What is the role of cytochrome c in apoptosis?

During the operation of the malate-aspartate shuttle, what process does NOT occur?

Quiz 19: Oxidative Phosphorylation and Photophosphorylation

Which statement is FALSE regarding 2,4-dinitrophenol?

Which statement explains why the [ATP]/[ADP][Pi] ratio is relatively stable in a cell?

Which protein is NOT portion encoded in human mitochondrial DNA?

What will NOT occur when 2,4-dinitrophenol (an uncoupler of oxidative phosphorylation) is added to actively respiring mitochondria?

In some organisms, an alternative oxidase will accept electrons from ubiquinol and reduce oxygen to water with no associated proton translocation. What would be a consequence of having this oxidase active?

What effect will increasing the number of c subunits in ATP synthase have on the P:O ratio?

Which statement is TRUE regarding the gamma ( γ\gammaγ ) subunit of ATP synthase?

Which statement does NOT describe characteristics of the protein inhibitor IF1?

Which list shows the proteins in the CORRECT order from highest to lowest reduction potential?

Which statement is TRUE regarding the reduction potential of mitochondrial glycerol 3 phosphate dehydrogenase?

Which complex in the electron-transport chain contains copper ions?

Cytochrome P-450 gets its name from what characteristic?

What mechanism accounts for mitochondrial inheritance in sexual reproduction in animals?

Which step is NOT part of the proton-translocation process in ATP synthase?

In which pairing are both transporters symports?

Which statement is FALSE regarding ATP synthase?

What is the P:O ratio for electrons entering the electron-transport chain that originate from reoxidation of acyl-CoA dehydrogenase?

What compound is a product of the reaction involving the superoxide free radical catalyzed by superoxide dismutase?

What is the role of cytochrome c in apoptosis?

During the operation of the malate-aspartate shuttle, what process does NOT occur?

Which statement explains why the [ATP]/[ADP][P_i] ratio is relatively stable in a cell?

Which statement is TRUE regarding the gamma ( $\gamma$ ) subunit of ATP synthase?

Which statement does NOT describe characteristics of the protein inhibitor IF₁?