Question 1

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

Accepted Answer

A)  acyl-CoA dehydrogenase $\rightarrow$  ETF:Q oxidoreductase $\rightarrow$  ETF 
B)  ETF $\rightarrow$  ETF:Q oxidoreductase $\rightarrow$ acyl-CoA dehydrogenase 
C)  ETF:Q oxidoreductase $\rightarrow$  acyl-CoA dehydrogenase$\rightarrow$ ETF 
D)  ETF:Q oxidoreductase $\rightarrow$ ETF$\rightarrow$ acyl-CoA dehydrogenase 
E)  ETF $\rightarrow$  acyl-CoA dehydrogenase $\rightarrow$ ETF:Q oxidoreductase 
A)  acyl-CoA dehydrogenase $\rightarrow$  ETF:Q oxidoreductase $\rightarrow$  ETF 
B)  ETF $\rightarrow$  ETF:Q oxidoreductase $\rightarrow$ acyl-CoA dehydrogenase 
C)  ETF:Q oxidoreductase $\rightarrow$  acyl-CoA dehydrogenase$\rightarrow$ ETF 
D)  ETF:Q oxidoreductase $\rightarrow$ ETF$\rightarrow$ acyl-CoA dehydrogenase 
E)  ETF $\rightarrow$  acyl-CoA dehydrogenase $\rightarrow$ ETF:Q oxidoreductase

Question 2

The rate of oxidative phosphorylation in mitochondria is controlled primarily by:

Accepted Answer

A)  feedback inhibition by CO2. 
B)  the availability of NADH from the TCA cycle. 
C)  the concentration of citrate (or) the glycerol-3-phosphate shuttle. 
D)  the mass-action ratio of the ATD-ADP system. 
E)  the presence of thermogenin. 
A)  feedback inhibition by CO2. 
B)  the availability of NADH from the TCA cycle. 
C)  the concentration of citrate (or) the glycerol-3-phosphate shuttle. 
D)  the mass-action ratio of the ATD-ADP system. 
E)  the presence of thermogenin.

Question 3

The oxidation of a particular hydroxy substrate to a keto product by mitochondria has a P/O ratio of less than 2. The initial oxidation step is very likely directly coupled to the:

Accepted Answer

A)  oxidation of a flavoprotein. 
B)  oxidation of a pyridine nucleotide. 
C)  reduction of a flavoprotein. 
D)  reduction of a pyridine nucleotide. 
E)  reduction of cytochrome a3. 
A)  oxidation of a flavoprotein. 
B)  oxidation of a pyridine nucleotide. 
C)  reduction of a flavoprotein. 
D)  reduction of a pyridine nucleotide. 
E)  reduction of cytochrome a3.

Question 4

The skunk cabbage (Symphocarpus foetidus) can maintain a temperature of 10-25 °C higher than the temperature of the surrounding air. Suggest a mechanism for this.

Accepted Answer

The skunk cabbage (Symplocarpus foetidus

Question 5

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

Accepted Answer

A)  The P:O ratio will increase. 
B)  The rate of NADH reoxidation at Complex I will increase. 
C)  The rate of oxidation of intermediates in the citric acid cycle will increase. 
D)  Proton export from the matrix will occur. 
E)  Heat will be released. 
A)  The P:O ratio will increase. 
B)  The rate of NADH reoxidation at Complex I will increase. 
C)  The rate of oxidation of intermediates in the citric acid cycle will increase. 
D)  Proton export from the matrix will occur. 
E)  Heat will be released.

Question 6

Cytochrome c interacts with multiple different proteins (for example: complex III, Complex IV, Apaf-1, sulfite oxidase and others). It is a small protein (~110 amino acids) and has a very low rate of mutation. Are these two aspects consistent with each other? Why or why not?

Accepted Answer

Yes, the fact that cytochrome c interact

Question 7

Which statement does NOT describe a difference between the inner and outer mitochondrial membranes?

Accepted Answer

A)  The outer mitochondrial membrane contains porins, whereas the inner mitochondrial membrane does not. 
B)  The outer mitochondrial membrane is permeable to large proteins (Mr > 10,000), whereas the inner mitochondrial membrane is not. 
C)  A pH gradient exists across the inner mitochondrial membrane but not the outer mitochondrial membrane. 
D)  The inner mitochondrial membrane contains a smaller percentage of lipid relative to protein compared with the outer mitochondrial membrane. 
E)  The outer mitochondrial membrane has a smaller surface area than the inner mitochondrial membrane. 
A)  The outer mitochondrial membrane contains porins, whereas the inner mitochondrial membrane does not. 
B)  The outer mitochondrial membrane is permeable to large proteins (Mr > 10,000), whereas the inner mitochondrial membrane is not. 
C)  A pH gradient exists across the inner mitochondrial membrane but not the outer mitochondrial membrane. 
D)  The inner mitochondrial membrane contains a smaller percentage of lipid relative to protein compared with the outer mitochondrial membrane. 
E)  The outer mitochondrial membrane has a smaller surface area than the inner mitochondrial membrane.

Question 8

Which protein is NOT portion encoded in human mitochondrial DNA?

Accepted Answer

A)  Complex I (NADH dehydrogenase) 
B)  Complex II (succinate dehydrogenase) 
C)  Complex III (ubiquinone:cytochrome c oxidoreductase) 
D)  cytochrome c 
E)  Complex IV (cytochrome oxidase) 
A)  Complex I (NADH dehydrogenase) 
B)  Complex II (succinate dehydrogenase) 
C)  Complex III (ubiquinone:cytochrome c oxidoreductase) 
D)  cytochrome c 
E)  Complex IV (cytochrome oxidase)

Question 9

Which statement is NOT true of the proton motive force (pmf)?

Accepted Answer

A)  One component of the pmf is the chemical gradient of protons. 
B)  One component of the pmf is the charge gradient of protons. 
C)  Generation of the pmf in mitochondria requires succinate. 
D)  The pmf is generated by the electron transport chain in mitochondria. 
E)  The pmf drives ATP synthesis in mitochondria. 
A)  One component of the pmf is the chemical gradient of protons. 
B)  One component of the pmf is the charge gradient of protons. 
C)  Generation of the pmf in mitochondria requires succinate. 
D)  The pmf is generated by the electron transport chain in mitochondria. 
E)  The pmf drives ATP synthesis in mitochondria.

Question 10

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

Accepted Answer

A)  water 
B)  hydrogen peroxide 
C)  reduced glutathione 
D)  oxidized glutathione 
E)  NADPH 
A)  water 
B)  hydrogen peroxide 
C)  reduced glutathione 
D)  oxidized glutathione 
E)  NADPH

Question 11

Which statement about energy conservation in the mitochondrion is FALSE?

Accepted Answer

A)  Drugs that inhibits the ATP synthase will also inhibit the flow of electrons down the chain of carriers. 
B)  For oxidative phosphorylation to occur, it is essential to have a closed membranous structure with an inside and an outside. 
C)  The yield of ATP per mole of oxidizable substrate depends on the substrate. 
D)  Uncouplers (such as dinitrophenol) have exactly the same effect on electron transfer as inhibitors such as cyanide; both block further electron transfer to oxygen. 
E)  Uncouplers "short circuit" the proton gradient, thereby dissipating the proton motive force as heat. 
A)  Drugs that inhibits the ATP synthase will also inhibit the flow of electrons down the chain of carriers. 
B)  For oxidative phosphorylation to occur, it is essential to have a closed membranous structure with an inside and an outside. 
C)  The yield of ATP per mole of oxidizable substrate depends on the substrate. 
D)  Uncouplers (such as dinitrophenol) have exactly the same effect on electron transfer as inhibitors such as cyanide; both block further electron transfer to oxygen. 
E)  Uncouplers "short circuit" the proton gradient, thereby dissipating the proton motive force as heat.

Question 12

Which statement is FALSE concerning Complex III and the Q cycle?

Accepted Answer

A)  Both Q and QH2 are substrates for Complex III. 
B)  Four protons are released on the P side of the membrane for every two electrons transferred to cytochrome c. 
C)  This protein contains both iron-sulfur clusters and heme as prosthetic groups. 
D)  Two protons from the matrix side are used to generate QH2 from the semiquinone radical. 
E)  Overall, in each cycle one cytochrome c is reduced for every QH2 oxidized (net). 
A)  Both Q and QH2 are substrates for Complex III. 
B)  Four protons are released on the P side of the membrane for every two electrons transferred to cytochrome c. 
C)  This protein contains both iron-sulfur clusters and heme as prosthetic groups. 
D)  Two protons from the matrix side are used to generate QH2 from the semiquinone radical. 
E)  Overall, in each cycle one cytochrome c is reduced for every QH2 oxidized (net).

Question 13

In the reoxidation of QH2 by purified ubiquinone-cytochrome c reductase (Complex III) from heart muscle, the overall stoichiometry of the reaction requires 2 mol of cytochrome c per mole of QH2 because:

Accepted Answer

A)  cytochrome c is a one-electron acceptor, whereas QH2 is a two-electron donor. 
B)  cytochrome c is a two-electron acceptor, whereas QH2 is a one-electron donor. 
C)  cytochrome c is water soluble and operates between the inner and outer mitochondrial membranes 
D)  heart muscle has a high rate of oxidative metabolism, and therefore requires twice as much cytochrome c as QH2 for electron transfer to proceed normally. 
E)  two molecules of cytochrome c must first combine physically before they are catalytically active. 
A)  cytochrome c is a one-electron acceptor, whereas QH2 is a two-electron donor. 
B)  cytochrome c is a two-electron acceptor, whereas QH2 is a one-electron donor. 
C)  cytochrome c is water soluble and operates between the inner and outer mitochondrial membranes 
D)  heart muscle has a high rate of oxidative metabolism, and therefore requires twice as much cytochrome c as QH2 for electron transfer to proceed normally. 
E)  two molecules of cytochrome c must first combine physically before they are catalytically active.

Question 14

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

Accepted Answer

A)  This protein is relatively small (O portion of ATP synthase. 
D)  This protein functions as a dimer when it is inhibiting ATP synthesis. 
E)  This protein inhibits ATP hydrolysis by ATP synthase. 
A)  This protein is relatively small (O portion of ATP synthase. 
D)  This protein functions as a dimer when it is inhibiting ATP synthesis. 
E)  This protein inhibits ATP hydrolysis by ATP synthase.

Question 15

Describe the role of cytochrome c in apoptosis.

Accepted Answer

Cytochrome c plays a crucial role in the

Question 16

Cytochrome P-450 gets its name from what characteristic?

Accepted Answer

A)  It is a protein that is 450 amino acids long. 
B)  It fluoresces at 450 nm. 
C)  It absorbs light at 450 nm. 
D)  It has a reduction potential of -450 mV. 
E)  It contains a 450 Dalton prosthetic group. 
A)  It is a protein that is 450 amino acids long. 
B)  It fluoresces at 450 nm. 
C)  It absorbs light at 450 nm. 
D)  It has a reduction potential of -450 mV. 
E)  It contains a 450 Dalton prosthetic group.

Question 17

Which protein associated with electron transport below is NOT a flavoprotein?

Accepted Answer

A)  NADH dehydrogenase 
B)  mitochondrial glycerol-3-phosphate dehydrogenase 
C)  cytochrome oxidase 
D)  succinate dehydrogenase 
E)  acyl-CoA dehydrogenase 
A)  NADH dehydrogenase 
B)  mitochondrial glycerol-3-phosphate dehydrogenase 
C)  cytochrome oxidase 
D)  succinate dehydrogenase 
E)  acyl-CoA dehydrogenase

Question 18

Although molecular oxygen (O2) does not participate directly in any of the reactions of the citric acid cycle, the cycle operates only when O2 is present. Explain this observation.

Accepted Answer

The citric acid cycle, also known as the

Question 19

Give an example of (a) an uncoupler of oxidative phosphorylation, and (b) an inhibitor of respiration. (c) Describe the difference in the effects of such uncouplers and inhibitors on mitochondrial function.

Accepted Answer

(a) An example of an uncoupler of oxidat

Question 20

Which statement is FALSE regarding 2,4-dinitrophenol?

Accepted Answer

A)  It is a proton carrier ionophore. 
B)  It may be either neutral or negatively charged. 
C)  It is soluble in the lipid core of membranes. 
D)  It requires a specific transporter to enter mitochondria. 
E)  It decreases ATP synthesis will increasing oxygen consumption. 
A)  It is a proton carrier ionophore. 
B)  It may be either neutral or negatively charged. 
C)  It is soluble in the lipid core of membranes. 
D)  It requires a specific transporter to enter mitochondria. 
E)  It decreases ATP synthesis will increasing oxygen consumption.

Exam 19: Oxidative Phosphorylation and Photophosphorylation

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

The rate of oxidative phosphorylation in mitochondria is controlled primarily by:

The oxidation of a particular hydroxy substrate to a keto product by mitochondria has a P/O ratio of less than 2. The initial oxidation step is very likely directly coupled to the:

The skunk cabbage (Symphocarpus foetidus) can maintain a temperature of 10-25 °C higher than the temperature of the surrounding air. Suggest a mechanism for this.

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

Cytochrome c interacts with multiple different proteins (for example: complex III, Complex IV, Apaf-1, sulfite oxidase and others). It is a small protein (~110 amino acids) and has a very low rate of mutation. Are these two aspects consistent with each other? Why or why not?

Which statement does NOT describe a difference between the inner and outer mitochondrial membranes?

Which protein is NOT portion encoded in human mitochondrial DNA?

Which statement is NOT true of the proton motive force (pmf)?

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

Which statement about energy conservation in the mitochondrion is FALSE?

Which statement is FALSE concerning Complex III and the Q cycle?

In the reoxidation of QH2 by purified ubiquinone-cytochrome c reductase (Complex III) from heart muscle, the overall stoichiometry of the reaction requires 2 mol of cytochrome c per mole of QH2 because:

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

Describe the role of cytochrome c in apoptosis.

Cytochrome P-450 gets its name from what characteristic?

Which protein associated with electron transport below is NOT a flavoprotein?

Although molecular oxygen (O2) does not participate directly in any of the reactions of the citric acid cycle, the cycle operates only when O2 is present. Explain this observation.

Give an example of (a) an uncoupler of oxidative phosphorylation, and (b) an inhibitor of respiration. (c) Describe the difference in the effects of such uncouplers and inhibitors on mitochondrial function.

Which statement is FALSE regarding 2,4-dinitrophenol?

The Foundations of Biochemistry

Water

Amino Acids, Peptides, and Proteins

The Three-Dimensional Structure of Proteins

Protein Function

Enzymes

Carbohydrates and Glycobiology

Nucleotides and Nucleic Acids

DNA-Based Information Technologies

Lipids

Biological Membranes and Transport

Biosignaling

Bioenergetics and Biochemical Reaction Types

Glycolysis, Gluconeogenesis, and the Pentose Phosphate Pathway

Principles of Metabolic Regulation

The Citric Acid Cycle

Fatty Acid Catabolism

Amino Acid Oxidation and the Production of Urea

Carbohydrate Biosynthesis in Plants and Bacteria

Lipid Biosynthesis

Biosynthesis of Amino Acids, Nucleotides, and Related Molecules

Hormonal Regulation and Integration of Mammalian Metabolism

Genes and Chromosomes

DNA Metabolism

RNA Metabolism

Protein Metabolism

Regulation of Gene Expression

Filters

In the reoxidation of QH₂ by purified ubiquinone-cytochrome c reductase (Complex III) from heart muscle, the overall stoichiometry of the reaction requires 2 mol of cytochrome c per mole of QH₂ because:

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

Although molecular oxygen (O₂) does not participate directly in any of the reactions of the citric acid cycle, the cycle operates only when O₂ is present. Explain this observation.