Deck 10: Aerobic Metabolism II: Electron Transport and Oxidative Phosphorylation

Question 1

Molecules involved in the conversion of oxidized proteins to their functional reduced sulfhydryl form include all of the following except __________.

A)thioredoxin
B) NADPH
C) catalase
D) thioredoxin reductase
E) None of the above are correct.

Answer 1

C

Question 2

All of the following are components of the electron transport chain except __________.

A) coenzyme Q
B) succinate dehydrogenase
C) coenzyme A
D) cytochrome c
E) NADH dehydrogenase

Answer 2

C

Question 3

The ETC component that transfers electrons directly to oxygen is __________.

A) cyt c
B) UQ
C) cyt bc₁
D) cytochrome oxidase
E) succinate dehydrogenase

Answer 3

D

Question 4

During the oxidation of NADH there are several steps in which E^o' is sufficient for ATP synthesis. These occur within __________.

A) Complexes I, II, and III
B) Complexes I, III, and IV
C) Complexes II, III, and IV
D) Complexes III, IV, and V
E) Complexes I, II, and IV

Question 5

Which of the following molecules inhibits Complex I of the electron transport chain?

A) Azide
B) Amytal
C) Cyanide
D) Arsenic
E) Carbon monoxide

Question 6

ATP synthesis and mitochondrial electron transport are coupled by __________.

A) protonmotive force
B) high energy intermediates
C) proton gradient
D) Both A and C are correct.
E) All of the above are correct.

Question 7

Evidence supporting the chemiosmotic theory includes all of the following except __________.

A) inhibitors of ATP synthesis have been shown to dissipate the proton gradient
B) mitochondria with disrupted membranes cannot synthesize ATP
C) ATP synthesis is depressed when mitochondrial swelling occurs as a result of osmotic changes
D) the pH of a weakly buffered suspension of mitochondria rises when O₂ added.
E) actively respiring mitochondria expel protons

Question 8

Examples of uncouplers include __________.

A) DNP
B) antimycin
C) gramicidin
D) Both A and B are correct.
E) Both A and C are correct.

Question 9

In the ATP synthase, the F_o factor __________.

A) has three types of subunits
B) possesses ATPase activity
C) is a transmembrane proton channel
D) Both A and B are correct.
E) Both A and C are correct.

Question 10

The maximum P/O ratio of FADH₂ is __________.

A) 1.5
B) 1.75
C) 2.0
D) 2.5
E) 3.0

Question 11

The control of aerobic respiration by __________ is referred to as respiratory control.

A) HPO₄^-2
B) NADH
C) FADH₂
D) citrate
E) ADP

Question 12

The first ROS formed during the reduction of oxygen is __________.

A) hydrogen peroxide
B) hydroxyl radical
C) singlet oxygen
D) superoxide radical
E) None of the above are correct.

Question 13

The reaction of Fe⁺² with H₂O₂ results in the production of __________.

A) hydroxyl radical
B) hydroxide ion
C) superoxide radical
D) Both A and B are correct.
E) Both A and C are correct.

Question 14

ROS are generated during __________.

A) xenobiotic metabolism
B) respiratory burst
C) ionizing radiation
D) Both A and B are correct.
E) All the above are correct.

Question 15

Glutathione peroxidase __________.

A) converts organic peroxides into alcohols
B) generates GSH from GSSG
C) reduces H₂O₂ into H₂O
D) Both A and B are correct.
E) Both A and C are correct.

Question 16

The NADPH required for the generation of GSH from GSSG in synthesized by the reactions of __________.

A) the pentose phosphate pathway
B) glycolysis
C) the citric acid cycle
D) Both A and B are correct.
E) Both A and C are correct.

Question 17

Glutathione peroxidase requires __________ for full activity.

A) sulfur
B) copper
C) iron
D) selenium
E) magnesium

Question 18

Examples of antioxidants include all of the following except __________.

A) ascorbic acid
B) carotene
C) -tocopherol
D) hydroquinone
E) gramicidin

Question 19

One of the mechanisms by which vitamin C protects membrane is by __________.

A) regenerating reduced -tocopherol
B) reacting with proline
C) reacting with peroxyl radicals
D) Both A and B are correct.
E) Both A and C are correct.

Question 20

The ultimate electron acceptor of the mitochondrial electron transport system is __________.

A) coenzyme Q
B) NADPH
C) O₂
D) H₂O
E) Both C and D are correct.

Question 21

The major sources of NADH that reduce Complex I of the ETC include __________.

A) fatty acid oxidation
B) CoQ
C) pentose phosphate pathway
D) the citric acid cycle
E) Both A and D are correct.

Question 22

In Complex III, electrons are transferred from UQH₂ to __________.

A) O₂
B) coenzyme Q
C) cytochrome c
D) FAD
E) NADH

Question 23

__________ is a metal cofactor of the cytochromes.

A) Fe
B) S
C) Co
D) Zn
E) Ca

Question 24

Carbon monoxide inhibits which of the following?

A) NADH dehydrogenase
B) Ubiquinone
C) Cytochrome oxidase
D) Succinate dehydrogenase
E) None of above are correct.

Question 25

Which of the following is the best reducing agent?

A) H₂O
B) O₂
C) FADH₂
D) FMNH₂
E) NADH

Question 26

The final product of oxidative phosphorylation is __________.

A) water
B) ADP
C) NADPH
D) ATP
E) FMNH₂

Question 27

__________ are hydrophobic molecules that dissipate ionic gradients.

A) Uncouplers
B) Ionophores
C) Xenobiotics
D) Radicals
E) None of the above are correct.

Question 28

The return of __________ into the mitochondrion is coupled to the formation of __________.

A) Ca⁺²; cAMP
B) Fe⁺²; CoQ
C) ADP; NADH
D) ADP; CoASH
E) H⁺; ATP

Question 29

The energy that is captured by the electron transport system is in the form of __________.

A) NADH
B) FADH₂
C) ATP
D) Both A and B are correct.
E) All the above are correct.

Question 30

The reducing power generated in the cytoplasm can be transferred into the mitochondrion by which of the following processes?

A) Glycerol phosphate shuttle
B) Malate-aspartate shuttle
C) The phosphate shuttle
D) A and B are correct.
E) All the above are correct.

Question 31

The cytochromes contain which type of prosthetic group?

A) FADH
B) Heme
C) TPP
D) Zinc⁺⁺
E) NAD ⁺

Question 32

The function of complex III is the transfer of electrons from __________.

A) coenzyme Q to Cyt c
B) NADH to CoQ
C) succinate to UQ
D) CoQ to NADH
E) UQ to succinate

Question 33

Which of the following complexes contain copper?

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

Question 34

Which of the following acts as an allosteric inhibitor of complex IV?

A) FMN
B) NADH
C) FADH₂
D) ATP
E) ADP

Question 35

Which of the following is not a step in the ATP synthesizing process?

A) ADP + P_i bind to the L site.
B) ATP is synthesized as the L conformation converts to the T conformation.
C) ATP is released as the T conformation converts to the O confirmation.
D) The O conformation binds ADP and Pi.
E) All of the above are correct.

Question 36

Nonshivering thermogenesis is regulated by which of the following?

A) Norepinephrine
B) Thermogenin
C) UCP₂
D) ATP
E) GTP

Question 37

The primary function of catalase is to __________,

A) detoxify peroxides
B) reduce the disulfide group
C) convert hydrogen peroxide to water
D) generate ROS
E) oxidize heme

Question 38

How many ATP are generated during the oxidation of one NADH?

A) 1
B) 2
C) 2.5
D) 3
E) 3.5

Question 39

Which of the following would not be classified as a ROS?

A) Oxygen
B) CH₃O^.
C) H-O-O^.
D) Hydroxide ion
E) None of the above are correct (all are ROS).

Question 40

The principal sources of electrons for the electron transport system is (are) which of the following?

A) Glycolysis
B) Citric acid cycle
C) Fatty acid oxidation
D) Both A and B are correct.
E) All the above are correct.

Question 41

The statement aerobic organisms use oxygen to generate energy required to maintain metabolic processes yet they risk damage caused by highly reactive oxygen molecules can be referred to as __________.

A) oxidation
B) reactive oxygen species
C) oxygen paradox
D) metabolic damage
E) thermodynamic inconsistency

Question 42

The ultimate waste products of aerobic cellular metabolism of oxygen include __________.

A) pyruvate
B) ethyl alcohol
C) carbon dioxide
D) carbon monoxide
E) Either A or B is correct.

Question 43

According to the solid state model of electron transport, electron transfer is efficient because __________.

A) electron transfer is the result of random collisions
B) there are short diffusion distances between components for mobile electron carriers
C) UQ is abundant
D) cytochrome c diffuses rapidly
E) electron carriers are mobile

Question 44

How many protons are required to drive the phosphorylation of ADP by the mitochondrial ATP synthase?

A) One
B) Two
C) Three
D) Four
E) Five

Question 45

A respiratory burst is initiated when NADPH reacts with oxygen to produce which of the following?

A) Superoxide anion
B) Water
C) Hydrogen peroxide
D) Hydroxyl radical
E) Peroxide radical

Question 46

Antimycin A inhibits cyt b in complex III. If this inhibitor is added to a suspension of mitochondria which of the following will increase in concentration?

A) NADH
B) Reduced cytochrome c₁
C) Reduced cytochrome c
D) NAD⁺
E) A and D are correct.

Question 47

What is the glycerol phosphate shuttle?

Question 48

What is a respiratory burst?

Question 49

Describe the principle features of the chemiosmotic theory.

Question 50

What are the principle sources of electrons for the electron transport system?

Question 51

How does nitrophenol inhibit ATP synthesis?

Question 52

Compare the amount of energy captured from a mole of glucose from glycolysis alone with that of oxidative phosphorylation.

Question 53

Describe the enzymatic activities used by cells to protect themselves from oxidative damage.

Question 54

Describe the types of cellular damage produced by ROS.

Question 55

What material accumulates when azide (N₃^-) is added to actively respiring mitochondria?

Question 56

When rotenone is added to actively respiring mitochondria the ratio of NADH to NAD⁺ increases, but the FADH₂/FAD remains unchanged. What step in the system is being inhibited?

Question 57

List some of the causes of reperfusion triggered cardiac cell damage.

Question 58

Explain why rotenone inhibits oxidative phosphorylation when the substrate is pyruvate but not when succinate is used.

Question 59

Describe the processes that are driven by mitochondrial electron transport.

Question 60

What would be the end products when the following substances are final electron acceptors in the electron transport system: nitrate, ferric ion, carbon dioxide, sulfate and sulfur?

Question 61

What advantages does dioxygen have over nitrate, ferric ion, carbon dioxide, sulfate and sulfur as final electron acceptors in the electron transport system?

Question 62

Describe the mechanism whereby uncoupling agents disrupt phosphorylation.

Question 63

The electron transport system consists of a series of oxidations rather than one reaction. Why is this an important feature of energy capture?

Question 64

Describe the role of UCP1 in nonshivering thermogenesis.

Question 65

What is the respirasome?

Question 66

A previous explanation of the mechanism of ATP synthesis referred to as the chemical coupling hypothesis, postulated that ATP synthesis occurs as s substrate level phosphorylation via a phosphate containing intermediate. The chemical coupling hypothesis failed to explain why mitochondrial membrane must be intact during ATP synthesis. How does the chemiosmotic theory account for this phenomena?

Question 67

Valinomycin is an ionophore antibiotic that renders biological membranes permeable to K⁺. Its side effects in patients with bacterial infections include a rise in body temperature and sweating. Explain.

Question 68

When taken in appropriate amounts Vitamin E protects the body from ROS. However when it is taken in excessive amounts Vitamin E can potentially make the body more susceptible to ROS. Explain.

Question 69

Proteins with ionizable cysteine thiol groups undergo reversible redox reactions. These proteins are referred to collectively as the cysteine proteome. Discuss the role of redox switches in the context of the cysteine proteome.

Question 70

According to the chemiosmotic theory, what would be the effect on oxidative phosphorylation of allowing other positive ions to diffuse across the inner mitochondrial membrane?

Question 71

Cyanide causes an irreversible inhibition of electron transport that prevents ATP synthesis, whereas the inhibitory effect of small amounts of dinitrophenol on ATP synthesis is reversible. Explain the difference.

Question 72

Explain why an inhibitor of complex I will not only cause an increase in the ratio of NADH to NAD⁺ but also an increase in the UQ/UQH ratio.

Question 73

Suppose that the mitochondrial complexes were not imbedded within the inner mitochondrial membrane. According to the chemiosmotic theory, what would be the consequences?

Question 74

What is the minimum voltage drop for individual electron transfer events in the mitochondrial electron transport system that is necessary for ATP synthesis?

Question 75

Ethanol is oxidized in the liver to form acetate, which is converted to acetyl-CoA. Determine how many molecules of ATP are produced from one mole of ethanol. Note that 2 mol of NADH are produced when ethanol is oxidized to form acetate.