Question 1

What is the role of FMN in complex I?

Accepted Answer

A)  Converts a two-electron transfer to a one-electron transfer. 
B)  Converts a one-electron transfer to a two-electron transfer. 
C)  Transports four H+ across the membrane. 
D)  None, there is no FMN in complex I. 
A)  Converts a two-electron transfer to a one-electron transfer. 
B)  Converts a one-electron transfer to a two-electron transfer. 
C)  Transports four H+ across the membrane. 
D)  None, there is no FMN in complex I.

Question 2

How many protons are translocated across the inner mitochondrial membrane by complex III for each pair of electrons passing through the electron transport chain?

Accepted Answer

A)  0 
B)  1 
C)  2 
D)  4 
A)  0 
B)  1 
C)  2 
D)  4

Question 3

White muscle cells contain fewer mitochondria than red muscle cells, so they rely on anaerobic glycolysis for energy needs.

Accepted Answer

A) True 
 B)False

Question 4

Electron transport chains occur only in the inner mitochondrial membrane of animal cells or the plasma membrane of bacteria.

Accepted Answer

A) True 
 B)False

Question 5

In the respiratory electron transport chain electrons are passed from .

Accepted Answer

A)  NADH and QH2 to O2  
B)  O2 to NAD+ and Q 
C)  O2 to NADH 
D)  ATP to O2 
A)  NADH and QH2 to O2  
B)  O2 to NAD+ and Q 
C)  O2 to NADH 
D)  ATP to O2

Question 6

The chemiosmotic theory explains

Accepted Answer

A)  the phosphorylation of ADP. 
B)  the electron transport chain. 
C)  the differences between inner and outer mitochondrial membranes. 
D)  the source of energy for formation of mitochondrial ATP. 
E)  aerobic respiration. 
A)  the phosphorylation of ADP. 
B)  the electron transport chain. 
C)  the differences between inner and outer mitochondrial membranes. 
D)  the source of energy for formation of mitochondrial ATP. 
E)  aerobic respiration.

Question 7

The inner membrane of mitochondria is permeable to , but not to .

Accepted Answer

A)  protons; water 
B)  cations; anions 
C)  charged molecules; uncharged molecules 
D)  uncharged molecules; charged molecules 
A)  protons; water 
B)  cations; anions 
C)  charged molecules; uncharged molecules 
D)  uncharged molecules; charged molecules

Question 8

In the presence of oxygen and in the absence of ADP, what occurs if the uncoupler 2,4-dinitrophenol is added to a suspension of normal mitochondria five minutes after an oxidizable substrate has been added?

Accepted Answer

A)  The substrate will be oxidized until the addition of the 2,4-dinitrophenol, which blocks further oxidation. 
B)  There is no effect; oxidation of the substrate continues at the same rate before and after the addition of 2,4-dinitrophenol. 
C)  The substrate cannot be oxidized either with or without 2,4-dinitrophenol unless ADP is also present. 
D)  Oxidation of the substrate does not occur until the 2,4-dinitrophenol is added. Afterward, oxidation proceeds rapidly until all of the substrate is consumed. 
A)  The substrate will be oxidized until the addition of the 2,4-dinitrophenol, which blocks further oxidation. 
B)  There is no effect; oxidation of the substrate continues at the same rate before and after the addition of 2,4-dinitrophenol. 
C)  The substrate cannot be oxidized either with or without 2,4-dinitrophenol unless ADP is also present. 
D)  Oxidation of the substrate does not occur until the 2,4-dinitrophenol is added. Afterward, oxidation proceeds rapidly until all of the substrate is consumed.

Question 9

NADH and QH2 for oxidative phosphorylation are produced only through the citric acid cycle under aerobic conditions.

Accepted Answer

A) True 
 B)False

Question 10

The protonmotive force is a result of .

Accepted Answer

A)  the flow of electrons from the matrix to the inner membrane space 
B)  a combination of an electrical potential and a chemical potential 
C)  the flow of protons within the inner mitochondrial membrane 
D)  All of the above 
A)  the flow of electrons from the matrix to the inner membrane space 
B)  a combination of an electrical potential and a chemical potential 
C)  the flow of protons within the inner mitochondrial membrane 
D)  All of the above

Question 11

Which best describe the structure of complex II?

Accepted Answer

A)  An L-shaped structure that spans the membrane and partially extends into the mitochondrial matrix. 
B)  A structure firmly anchored to the membrane by many a-helices that span the lipid-bilayer. 
C)  Three identical multisubunit enzymes that associate to form a mushroom-shaped structure. 
D)  Has a core structure of three conserved subunits, one of which forms a b-barrel on the exterior surface of the membrane. 
A)  An L-shaped structure that spans the membrane and partially extends into the mitochondrial matrix. 
B)  A structure firmly anchored to the membrane by many a-helices that span the lipid-bilayer. 
C)  Three identical multisubunit enzymes that associate to form a mushroom-shaped structure. 
D)  Has a core structure of three conserved subunits, one of which forms a b-barrel on the exterior surface of the membrane.

Question 12

During the Q-cycle molecules) of QH2 isare) oxidized and molecules) of Q isare) produced.

Accepted Answer

A)  1; 1 
B)  1; 2 
C)  2; 1 
D)  2; 2 
A)  1; 1 
B)  1; 2 
C)  2; 1 
D)  2; 2

Question 13

For normal mitochondria in the presence of an oxidizable substrate and an uncoupler such as 2,4-dinitrophenol which do you expect?

Accepted Answer

A)  oxygen consumption even in the absence of ADP 
B)  a rise in temperature to dissipate energy that would otherwise have been used to generate ATP 
C)  the flow of protons into the mitochondria matrix 
D)  All of the above 
E)  None of the above 
A)  oxygen consumption even in the absence of ADP 
B)  a rise in temperature to dissipate energy that would otherwise have been used to generate ATP 
C)  the flow of protons into the mitochondria matrix 
D)  All of the above 
E)  None of the above

Question 14

Which of the following is mismatched?

Accepted Answer

A)  outer mitochondrial membrane - permeable to ions and water 
B)  inner mitochondrial membrane - permeable to O2 and CO2 
C)  outer mitochondrial membrane - folded into cristae 
D)  inner mitochondrial membrane - location of ATP synthase 
E)  matrix - some ATP synthase subunits extend here 
A)  outer mitochondrial membrane - permeable to ions and water 
B)  inner mitochondrial membrane - permeable to O2 and CO2 
C)  outer mitochondrial membrane - folded into cristae 
D)  inner mitochondrial membrane - location of ATP synthase 
E)  matrix - some ATP synthase subunits extend here

Question 15

In the presence of an uncoupler, more substrate can be oxidized.

Accepted Answer

A) True 
 B)False

Question 16

Fumarate reductase essentially catalyzes the reverse reaction catalyzed by the succinate dehydrogenase.

Accepted Answer

A) True 
 B)False

Question 17

How many protons are translocated across the membrane by complex I for every pair of electrons that are passed from NADH to QH2?

Accepted Answer

A)  1 
B)  2 
C)  3 
D)  4 
E)  5 
A)  1 
B)  2 
C)  3 
D)  4 
E)  5

Question 18

Which complex in the electron transport chain does not contribute to the proton gradient?

Accepted Answer

A)  I 
B)  II 
C)  III 
D)  IV 
E)  V 
A)  I 
B)  II 
C)  III 
D)  IV 
E)  V

Question 19

The source of energy to produce ATP in mitochondria is a proton gradient formed across the outer mitochondrial membrane.

Accepted Answer

A) True 
 B)False

Question 20

The presence of superoxide dismutase (SOD) in mammalian cells can be harmful or beneficial, depending on the location.

Accepted Answer

A) True 
 B)False

Exam 14: Electron Transport and Oxidative Phosphorylation

What is the role of FMN in complex I?

How many protons are translocated across the inner mitochondrial membrane by complex III for each pair of electrons passing through the electron transport chain?

White muscle cells contain fewer mitochondria than red muscle cells, so they rely on anaerobic glycolysis for energy needs.

Electron transport chains occur only in the inner mitochondrial membrane of animal cells or the plasma membrane of bacteria.

In the respiratory electron transport chain electrons are passed from .

The chemiosmotic theory explains

The inner membrane of mitochondria is permeable to , but not to .

In the presence of oxygen and in the absence of ADP, what occurs if the uncoupler 2,4-dinitrophenol is added to a suspension of normal mitochondria five minutes after an oxidizable substrate has been added?

NADH and QH2 for oxidative phosphorylation are produced only through the citric acid cycle under aerobic conditions.

The protonmotive force is a result of .

Which best describe the structure of complex II?

During the Q-cycle molecules) of QH2 isare) oxidized and molecules) of Q isare) produced.

For normal mitochondria in the presence of an oxidizable substrate and an uncoupler such as 2,4-dinitrophenol which do you expect?

Which of the following is mismatched?

In the presence of an uncoupler, more substrate can be oxidized.

Fumarate reductase essentially catalyzes the reverse reaction catalyzed by the succinate dehydrogenase.

How many protons are translocated across the membrane by complex I for every pair of electrons that are passed from NADH to QH2?

Which complex in the electron transport chain does not contribute to the proton gradient?

The source of energy to produce ATP in mitochondria is a proton gradient formed across the outer mitochondrial membrane.

The presence of superoxide dismutase (SOD) in mammalian cells can be harmful or beneficial, depending on the location.

Introduction to Biochemistry

Water

Amino Acids and the Primary Structures of Proteins

Proteins: Three-Dimensional Structure and Function

Properties of Enzymes

Mechanisms of Enzymes

Coenzymes and Vitamins

Carbohydrates

Lipids and Membranes

Introduction to Metabolism

Glycolysis

Gluconeogenesis, the Pentose Phosphate Pathway, and Glycogen Metabolism

The Citric Acid Cycle

Photosynthesis

Lipid Metabolism

Amino Acid Metabolism

Nucleotide Metabolism

Nucleic Acids

Dna Replication, Repair, and Recombination

Transcription and Rna Processing

Protein Synthesis

Recombinant Dna Technology

Filters

NADH and QH₂for oxidative phosphorylation are produced only through the citric acid cycle under aerobic conditions.

During the Q-cycle molecules) of QH₂isare) oxidized and molecules) of Q isare) produced.

How many protons are translocated across the membrane by complex I for every pair of electrons that are passed from NADH to QH₂?