Deck 15: Oxidative Phosphorylation

Question 1

The oxidation of FADH₂ to FAD involves the transfer of _____; the oxidation of NADH to NAD⁺ involves the transfer of _____.

A) a hydrogen atom and an H⁺; a hydride
B) two hydrogen atoms; a hydride
C) a hydride and an H⁺; a hydrogen atom and an H⁺
D) a hydride; two hydrogen atoms
E) two hydrides; one hydride

Answer 1

two hydrogen atoms; a hydride

Question 2

Which of the following is the correct half reaction for the oxidation of acetaldehyde?

A) acetaldehyde + H₂O $\rarr$ acetate^- + 3H⁺ + 2e^-
B) acetate^- + 3H⁺ + 2e^- $\rarr$ acetaldehyde + H₂O
C) acetaldehyde + 2 H⁺ + 2e^- $\rarr$ ethanol
D) ethanol $\rarr$ acetaldehyde + 2 H⁺ + 2e^-
E) acetaldehyde + CO₂ + H⁺ + 2e^- $\rarr$ pyruvate^-

Answer 2

acetaldehyde + H₂O $\rarr$ acetate^- + 3H⁺ + 2e^-

Question 3

If the following half-reactions are combined, what is the potential for the spontaneous reaction?
Oxaloacetate^- + 2H⁺ + 2e^- $\rarr$ malate^- = -0.166
NAD⁺ + H⁺ + 2e^- $\rarr$ NADH 11ee7c6d_74e2_e452_ae82_f5f2b4bfa620_TBW1044_11= -0.315

A) -0.481 V
B) -0.149 V
C) 0.0523 V
D) 0.149 V
E) .0481 V

Answer 3

0.149 V

Question 4

If the reduction potential for NAD⁺ is -0.315 V and the reduction potential for oxygen is 0.815 V, what is the potential for the oxidation of NADH by oxygen?

A) -1.13 V
B) -0.50 V
C) 0.185 V
D) 0.50 V
E) 1.13 V

Question 5

In a muscle cell at 37 C, if the concentrations of pyruvate and lactate are 100 $\mu$ M and 50 $\mu$ M respectively, what is the actual reduction potential if for pyruvate reduction is -0.185 V?

A) -0.194 V
B) -0.186 V
C) -0.176 V
D) 0.176 V
E) 0.194 V

Question 6

What is the $\Delta$ Gfor the reduction of pyruvate to lactate by NADH given the following half reactions?
Pyruvate^- + 2H⁺ + 2e^- $\rarr$ lactate^-   = -0.185
NAD⁺ + H⁺ + 2e^- $\rarr$ NADH   11ee7c6d_c899_8e54_ae82_0910aec0b20b_TBW1044_11= -0.315

A) -96.5 kJ/mol
B) -25.1 kJ/mol
C) -12.5 kJ/mol
D) 25.1 kJ/mol
E) 96.5 kJ/mol

Question 7

What does the reduction potential of 0.815 V for the reduction of water to oxygen indicate?

A) water is a very strong reducing agent
B) water is a very strong reducing agent and oxygen is a very strong oxidizing agent
C) oxygen is a very strong oxidizing agent
D) water will be spontaneously reduced to oxygen
E) none of the above

Question 8

What genes are found in the mitochondrial genome?

A) electron transport proteins
B) citric acid cycle enzymes
C) fatty acid oxidation enzymes
D) outer membrane transport proteins
E) none of the above

Question 9

Which of the following transport mechanisms is used in the inner mitochondrial membrane?
IMS = intermembrane space

A) antiport of ATP from IMS to matrix, ADP from matrix to IMS
B) symport of ATP and H⁺ from matrix to IMS
C) symport of P_i and H⁺ from IMS to matrix
D) antiport of ADP from IMS to matrix, P_i from matrix to IMS
E) symport of ADP and H⁺ from IMS to matrix

Question 10

Which of the following is a source of ubiquinol?

A) Complex I
B) fatty acyl-CoA dehydrogenase
C) succinate dehydrogenase
D) mitochondrial dehydrogenase
E) all of the above

Question 11

The cytochromes undergo which of the following oxidation reactions?

A) Fe³⁺ $\rarr$ Fe²⁺
B) Fe⁰ $\rarr$ Fe²⁺
C) Fe²⁺ $\rarr$ Fe³⁺
D) Cu¹⁺ $\rarr$ Cu²⁺
E) Cu²⁺ $\rarr$ Cu¹⁺

Question 12

How many protons are moved across the inner mitochondrial membrane at Complex III?

A) 1
B) 2
C) 3
D) 4
E) none of the above

Question 13

Ubiquinone is a _____ molecule that serves as a _____ electron carrier; cytochrome c is a _____ molecule that serves as a _____ electron carrier.

A) hydrophobic; 2; hydrophilic; 1
B) hydrophobic; 1; hydrophilic; 1
C) hydrophilic; 2; hydrophobic; 2
D) hydrophilic; 2; hydrophobic; 1
E) hydrophobic; 1; hydrophilic; 2

Question 14

What free radical is thought to be commonly produced by the electron transport chain?

A) hydroxyl
B) peroxyl
C) superoxide
D) hydrogen peroxyl
E) all of the above

Question 15

How many ATP can be produced from the complete oxidation of glucose if the malate-aspartate shuttle is used?

A) 2
B) 19.5
C) 28
D) 30
E) 32

Question 16

If an ATP synthase has 12 c subunits, how many protons must move through the enzyme to produce one ATP?

A) 2.5
B) 3
C) 4
D) 10
E) 12

Question 17

Which subunit of ATP synthase is responsible for the catalysis of ATP formation?

A) a
B) c
C) $\alpha$
D) $\beta$
E) $\gamma$

Question 18

What is the P/O ratio for the oxidation of ubiquinone if three protons are required to synthesize one ATP?

A) 1
B) 1.5
C) 2
D) 3
E) 3.3

Question 19

Under normal metabolic conditions, the difference in pH between the matrix and intermembrane space is ___ suggesting that the processes of electron transport and oxidative phosphorylation ___.

Question 20

The F₀ component of ATP synthase contains ___ subunits; the F1 component contains ___ subunits.