Deck 18: Electron Transport and Oxidative Phosphorylation

Question 1

The electrons formed from the aerobic oxidation of glucose are
I.ultimately transferred to O₂ after several other transfer reactions.
II.transferred to the coenzymes NAD⁺ and FAD.
III.directly transferred to O₂ during the citric acid cycle.
IV.transferred to succinate and arachidonic acid.

A)I only
B)II only
C)I, II
D)II, III, IV
E)I, II, III

Answer 1

I, II

Question 2

Matching
Choose the correct answer from the list. Not all the answers will be used.
Protons moving through a transmembranc channel by "jumping" through an arrangement of hydrogen-bonded groups are described as moving through a proton ______.

A)shuttle
B)matrix
C)respiration
D)copper
E)heme
F)tunnel
G)plasma membrane
H)coenzyme Q
I)cytosol
J)antioxidant
K)wire
L)proton pump

Answer 2

wire

Question 3

According to the proposed reaction sequence presented in the chapter, cytochrome c oxidase obtains a fourth electron from a ____ residue adjacent to the heme a₃-ligated O₂, thus forming a transient radical.

A)serine
B)threonine
C)tyrosine
D)phenylalanine
E)tryptophan

Answer 3

tyrosine

Question 4

Matching
Choose the correct answer from the list. Not all the answers will be used.
The cytochromes within complex III all contain _____ groups.

A)shuttle
B)matrix
C)respiration
D)copper
E)heme
F)tunnel
G)plasma membrane
H)coenzyme Q
I)cytosol
J)antioxidant
K)wire
L)proton pump

Question 5

Matching
Choose the correct answer from the list. Not all the answers will be used.
Electrons from cytosolic NADH are transferred to the matrix via electron ______ systems.

A)shuttle
B)matrix
C)respiration
D)copper
E)heme
F)tunnel
G)plasma membrane
H)coenzyme Q
I)cytosol
J)antioxidant
K)wire
L)proton pump

Question 6

Matching
Choose the correct answer from the list. Not all the answers will be used.
Bacteria carry out electron transport in the _____.

A)shuttle
B)matrix
C)respiration
D)copper
E)heme
F)tunnel
G)plasma membrane
H)coenzyme Q
I)cytosol
J)antioxidant
K)wire
L)proton pump

Question 7

Approximately how many ATP molecules are synthesized from the oxidation of 1 NADH?

A)1
B)1.5
C)2
D)2.5
E)3

Question 8

One method used by newborn mammals to generate heat is referred to as nonshivering thermogenesis.This method utilizes a protein channel called ________ which is present in high levels inside the mitochondria of _____tissue.

A)thermogenin; muscle
B)UCP-1; muscle
C)thermogenin; brown adipose
D)UCP-1; white adipose
E)UCP-2; brown adipose

Question 9

Which of the following correctly ranks redox centers found in Complex I from lower to higher potential? A correct answer will contain redox centers which are found in only Complex I and will also rank those redox centers in order of lower to higher reduction potential.

A)FMN, Heme b₅₆₀, [2Fe-2S], CoQ
B)ubiquinone, [4Fe-4S], [2Fe-2S], FMN
C)FMN, [2Fe-2S], [4Fe-4S]
D)Heme b₅₆₀, [2Fe-2S], [4Fe-4S], FAD
E)FAD, [2Fe-2S], [4Fe-4S], Heme b₅₆₀

Question 10

Matching
Choose the correct answer from the list. Not all the answers will be used.
Molecules that prevent oxidative damage by the superoxide radical possess ______ properties.

A)shuttle
B)matrix
C)respiration
D)copper
E)heme
F)tunnel
G)plasma membrane
H)coenzyme Q
I)cytosol
J)antioxidant
K)wire
L)proton pump

Question 11

Which of the following statements about the mitochondrial inner membrane is TRUE?
I.The inner membrane is permeable to CO₂, H₂O, and small ions.
II.The inner membrane contains several transport proteins and membrane bound
Enzymes.
III.In general, a higher inner membrane surface area correlates to a higher rate of
Respiration.
IV.The number of cristae reflects the respiratory activity of the cell.

A)I, II, III, IV
B)I, II, III
C)II only
D)II, III, IV
E)III, IV

Question 12

Which of the following is TRUE regarding the complexes within the electron transport system?
I.Complex II contributes twice as many protons to the gradient than Complex I
II.Inhibition of Complex II would decrease the total number of electrons moving through the electron transport chain.
III.Inhibition of Complex II would not alter the amount of free energy generated from electrons originating from NADH.
IV.Complex I can accept electrons with higher potential than Complex II is able to accept.

A)I, II, III, IV
B)I, II, III
C)II only
D)II, III
E)III, IV

Question 13

Based on the estimation presented in the chapter, how many ATP per glucose are synthesized by the aerobic metabolism in eukaryotes?

A)2
B)4
C)32
D)38
E)60

Question 14

Matching
Choose the correct answer from the list. Not all the answers will be used.
Complexes I and II each transfer electrons to ______.

A)shuttle
B)matrix
C)respiration
D)copper
E)heme
F)tunnel
G)plasma membrane
H)coenzyme Q
I)cytosol
J)antioxidant
K)wire
L)proton pump

Question 15

Matching
Choose the correct answer from the list. Not all the answers will be used.
The inner mitochondrial membrane divides the mitochondrion into the inner membrane space and the ______.

A)shuttle
B)matrix
C)respiration
D)copper
E)heme
F)tunnel
G)plasma membrane
H)coenzyme Q
I)cytosol
J)antioxidant
K)wire
L)proton pump

Question 16

Matching
Choose the correct answer from the list. Not all the answers will be used.
Cytochrome c oxidase contains four redox centers: two heme groups and two redox centers containing_______.

A)shuttle
B)matrix
C)respiration
D)copper
E)heme
F)tunnel
G)plasma membrane
H)coenzyme Q
I)cytosol
J)antioxidant
K)wire
L)proton pump

Question 17

Matching
Choose the correct answer from the list. Not all the answers will be used.
Bacteriorhodopsin is an example of a light-driven ______ .

A)shuttle
B)matrix
C)respiration
D)copper
E)heme
F)tunnel
G)plasma membrane
H)coenzyme Q
I)cytosol
J)antioxidant
K)wire
L)proton pump

Question 18

A typical eukaryotic cell contains up to ____ mitochondria each bound by a smooth outer membrane.

A)2
B)20
C)2000
D)20,000
E)200,000

Question 19

Some degenerative diseases, such as Parkinson's disease, are associated with ______ damage to ______.

A)oxidative; mitochondria
B)thermogenic; mitochondria
C)free radical; nuclei
D)oxidative; nuclei
E)thermogenic; nuclei

Question 20

Matching
Choose the correct answer from the list. Not all the answers will be used.
The stoichiometric relationship of ATP synthesis to ______ is referred to as the P/O ratio.

A)shuttle
B)matrix
C)respiration
D)copper
E)heme
F)tunnel
G)plasma membrane
H)coenzyme Q
I)cytosol
J)antioxidant
K)wire
L)proton pump

Question 21

Phosphate (P_i)is transported into the mitochondria from the cytosol by a phosphate carrier which is driven by the

A)hydrolysis of ATP.
B)simultaneous transport of H⁺ into the mitochondrion.
C)simultaneous transport of ADP into the mitochondrion.
D)simultaneous transport of H⁺ out of the mitochondrion.
E)simultaneous transport of ATP out of the mitochondrion.

Question 22

Which of the following are TRUE statements regarding the structure of ATP synthase?

A)It has a membrane-embedded component called F₀ and a component found in the matrix referred to as F₁.
B)The $\gamma$ subunit acts as the proton "wire" allowing equilibration of the ion gradient.
C)Research indicates that the F₁ portion of the protein rotates in a circular counterclockwise direction.
D)A and B
E)A, B, and C

Question 23

Which of the following statements is(are)TRUE about oxidative phosphorylation?
I.Electron transport provides energy to pump protons into the intermembrane space.
II.An electrochemical gradient is formed across the inner mitochondrial membrane.
III.Potassium and sodium ions form an ionic gradient across the inner mitochondrial membrane.
IV.Complexes I, II, III, IV actively transport protons into the intermembrane space during electron transport.

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

Question 24

A poison that prevents the transfer of electrons from the last [Fe-S] cluster of Complex I to coenzyme Q is added to a suspension of actively respiring mitochondria.Which of the following will be observed?

A)ATP production would be impaired due to the uncoupling of oxidative phosphorylation from electron transport.
B)ATP production would be reduced due to inhibition of the CoQ subunit of ATP synthase.
C)ATP production would be reduced due to a decrease in the number of protons pumped out of the mitochondrial matrix.
D)ATP production would be halted completely due to the block in electron transport through the electron transport chain.
E)ATP production would be maintained at the normal rate due to functional overlap between Complex I and Complex II.

Question 25

The effects of a poison on actively respiring mitochondria are being studied to determine its mode of action.When the poison is added, every component of the electron transport chain is found to be in its reduced form based on spectroscopic analysis, and ATP production ceases entirely.It is reasoned that the poison is either blocking the final transfer of electrons to oxygen or is blocking the ATP synthase.Which of the following experiments will help unravel this dilemma?

A)Add a second blocking agent to interfere with either Complex I or Complex II along with the poison.
B)Add an artificial electron donor along with the poison.
C)Add an uncoupling agent along with the poison.
D)Any of the above would allow differentiation between these two possibilities.
E)None of the above will help distinguish between these two possibilities.

Question 26

Cyclonite is a poison that blocks electron transfer between cytochromes b_L and b_H.When this poison is added to a suspension of isolated mitochondria, and when spectroscopic analysis is performed,

A)the coenzyme Q pool will be found in the reduced state, and cytochrome c will be found in the oxidized state.
B)the coenzyme Q pool will be found in the oxidized state, and cytochrome c will be found in the reduced state.
C)the coenzyme Q pool will be found in both oxidized & reduced states, and cytochrome c will be found in only one state.
D)the coenzyme Q pool will be found in only one state, and cytochrome c will be found in both oxidized & reduced states.
E)both the coenzyme Q pool and cytochrome c will be found in both oxidized & reduced states.

Question 27

Which statement concerning Complex II of the electron transport chain is FALSE?
I.This complex oxidizes FADH₂ and reduces coenzyme Q.
II.This complex includes the covalently bound enzyme succinate dehydrogenase.
III.This complex pumps protons from the matrix to the intermembrane space.
IV.This complex also oxidizes succinate to fumarate in the citric acid cycle.

A)I, II
B)II only
C)II, III
D)III only
E)IV only

Question 28

In theory how many protons could be pumped under standard state conditions by Complex III per mol of CoQ oxidized, considering the following information? (NOTE: mt = mitochondria)

A)four or less protons
B)greater than four protons but less than or equal to six protons
C)greater than six protons but less than or equal to eight protons
D)greater than 8 protons
E)Cannot be determined from the information provided.

Question 29

Cyanide (CN^-)
I.inhibition can be restored by addition of succinate.
II.inhibition can be restored by addition of cytochrome c.
III.inhibits electron transport which stops consumption of oxygen.
IV.blocks transfer of electrons from CoQ to Complex III.

A)I, III, IV
B)I, III
C)II, III, IV
D)I only
E)III only

Question 30

In the electron transport chain, FMN can adopt ____ oxidation state(s)and is capable of accepting or donating ____ electron(s).

A)2; 2
B)2; 1 or 2
C)3; 2
D)3; 1 or 2
E)3; 1

Question 31

The rate of oxidative phosphorylation
I.is regulated by the availability of ADP and P_i.
II.is reduced when the ratio of [NADH]/[NAD⁺] is high.
III.increases with a higher concentration of reduced cytochrome c
IV.is regulated by activity of the ADP-ATP translocator.

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

Question 32

Antimycin A
I.inhibition can be restored by addition of succinate.
II.inhibition can be restored by addition of cytochrome c.
III.blocks consumption of oxygen.
IV.blocks transfer of electrons from CoQ to Complex III.

A)I, II, III, IV
B)I, II, III
C)II, III, IV
D)II, III
E)III only

Question 33

Which of the prosthetic groups listed can accept or donate either one or two electrons due to the stability of the semiquinone state?

A)cytochrome c
B)NADH
C)CoQ
D)[2Fe-2S]
E)Rieske center

Question 34

Consider the following half-reactions:

What is the for the following redox equation?

A)-1.130 V
B)-0.500 V
C)+0.500 V
D)+1.130 V
E)none of the above

Question 35

Based on the information in the chapter, which of the following is TRUE regarding Complex III?
I.A large portion of Complex III dissociates from the membrane bound portion of the complex.
II.Complex III contains three identical cytochrome redox centers.
III.The Q cycle allows stepwise reoxidation of the two electrons from CoQH₂.
IV.A change in conformation of iron sulfur protein (ISP)ensures that the Reiske center is reduced preferentially by CoQ^.-.

A)I only
B)I, II
C)III only
D)III, IV
E)I, III, IV

Question 36

Which of the following is TRUE regarding heme proteins?
I.Heme groups are capable of transferring electrons across large distances provided that some molecular network exists as a "path."
II.Heme groups are often buried in protein structure because the protein protects the heme and prevents it from indiscriminately transferring electrons.
III.The rate of electron transfer from a reduced heme is physiologically significant.
IV.Heme groups are often differentiated by their absorption spectrum.

A)I, III
B)I, III, IV.
C)I, II
D)II, IV
E)I, II, III, IV

Question 37

Which statement(s)concerning the mitochondrial F₀F₁ ATP synthase is FALSE?
I.The F₁ subunit includes rotating sets of $\alpha\beta$ dimers.
II.The F₀ subunit includes a ring of between 9 and 12 proton-carrying polypeptides.
III.The F₁ subunit undergoes a series of conformational changes throughout the course of reaction.

A)I, II, III
B)II, III
C)I only
D)III only
E)None of the options (I - III)is false.Options I-IV are all true.

Question 38

What is the net result of the successive reactions catalyzed by superoxide dismutase and catalase?

A)conversion of the free radical O₂^. to H₂O₂, which is converted to water and O₂
B)conversion of the free radical O₂^. to H₂O₂, which is converted to water and GSSG and water
C)conversion of the free radical O₂^. to peroxide, which is converted to CO₂ and water
D)conversion of the free radical O₂^. to carbon dioxide and water
E)none of the above

Question 39

Which of the following best describes the function of cytochrome c oxidase?

A)Cytochrome c oxidase oxidizes four consecutive cytochrome c molecules, via one-electron transfers, while simultaneously reducing one O₂ to two H₂O.
B)Cytochrome c oxidase oxidizes two consecutive cytochrome c molecules, via two-electron transfers, while simultaneously reducing one O₂ to two H₂O.
C)Cytochrome c oxidase oxidizes four consecutive cytochrome c molecules, via one-electron transfers, while simultaneously reducing two O₂ to two H₂O.
D)Cytochrome c oxidase oxidizes two consecutive cytochrome c molecules, via two- electron transfers, while simultaneously reducing two O₂ to two H₂O.

Question 40

Rotenone and amytal
I.inhibition can be restored by addition of succinate
II.inhibition can be restored by addition of cytochrome c.
III.blocks consumption of oxygen.
IV.blocks transfer of electrons from CoQ to Complex III.

A)I, II, III, IV
B)I, II, III
C)II, III, IV
D)III only
E)IV only

Question 41

An animal with the UCP-1 protein would
I.generate excess heat.
II.have lower energy levels.
III.generate ATP efficiently via oxidative phosphorylation.

A)I
B)I, II
C)I, II, III
D)I, III
E)II, III

Question 42

Use the table below to rank the redox centers in order to produce a favorable electron flow.

A)D, Q, F, C, Z
B)Q, F, C, D, Z
C)Z, Q, F, C, D
D)Z, F, C, D, Q
E)Z, Q, C, Q, D

Question 43

In a newly discovered electron transport complex a researcher has identified the redox center Fe-S, cytochrome c, and coenzyme Q.The researcher also knows that this complex ultimately passes its electrons to oxygen.What is most likely the redox center which completes this task?

A)Fe-S
B)2Fe-2S
C)coenzyme Q
D)cytochrome c
E)None of the above

Question 44

ATP forms (is produced)
I.upon transition from the loose to the tight form of the α and β subunit complex of ATP synthase.
II.as a result of the flux of electrons through the channel formed by F_o
III.as a result of the positive ions pumped into the matrix of the mitochondrion.

A)I, II, III
B)II, III
C)I, III
D)I only
E)II only

Question 45

The structure of ATP synthase changes in conformation as a result of

A)the rotation of the α and β subunits.
B)the rotation of the β subunit.
C)the rotation of ATP.
D)the rotation of the $\gamma$ subunit.
E)all of the above.

Question 46

Which conformation of the active sites in ATP synthase allows binding of substrates?

A)L state
B)O state
C)T state
D)C state
E)A and B

Question 47

In the electron transport chain, electrons are passed from redox center to redox center ____.

A)spontaneously due to the redox potential gradient.
B)in an ATP dependent fashion.
C)as a result of the addition of free energy.
D)as a result of the proton gradient.
E)with the assistance of a carrier protein.

Question 48

All of the following inhibit electron transport EXCEPT

A)oxaloacetate
B)rotenone
C)anitimycin A
D)cyanide
E)All of the above inhibit electron transport,

Question 49

Electrons from FADH₂ are delivered to ____ and electrons from NADH are delivered to ____ of the electron transport chain.

A)Complex I; Complex II
B)Complex I; Complex III
C)Complex II; Complex III
D)Complex II; Complex I
E)Complex I; Complex IV

Question 50

___ the gradient with the synthesis of ATP via oxidative phosphorylation.
I.The F_o portion of ATP synthase
II.Thermogenin uncouples
III.2,4-dinitrophenol (DNP)dissipates
IV.An ionophore capable of transporting potassium ions across the membrane

A)I, II, III, IV
B)II, III, IV
C)II, III
D)II only
E)I, IV