Deck 18: Oxidative Phosphorylation

Question 1

In the initial step of Complex I,two high-potential electrons are transferred from NADH to the ___________ prosthetic group of this complex.

Answer 1

FMN

Question 2

________________ carries electrons from Complex III to Complex IV.

Answer 2

Cytochrome c

Question 3

Acceptor control of oxidative phosphorylation means that the rate of respiration depends upon the level of __________.

Answer 3

ADP

Question 4

What term is used to describe an ATP-generating process in which an inorganic substance such as oxygen serves as the ultimate electron acceptor?

A) electron transport
B) respiration
C) fermentation
D) anaerobic phosphorylation
E) None of the answers is correct.

Question 5

Cytochrome c oxidase contains two heme A groups and three ______________ ions.

Question 6

What prosthetic group is present in complexes I,II,and III of electron transport?

A) semiquinone
B) flavin mononucleotide
C) coenzyme Q
D) heme group
E) iron-sulfur cluster

Question 7

What type of enzyme plays a key role in apoptosis?

A) cytochrome P450
B) electron-transport complexes
C) caspase
D) enzymes of the citric acid cycle
E) None of the answers is correct.

Question 8

_______________ is a molecular assembly in the inner mitochondrial membrane that carries out the synthesis of ATP.

Question 9

What name is given to the hypothesis proposed by Peter Mitchell that explains how ATP synthesis is coupled to electron transport?

A) chemiosmotic hypothesis
B) oxidative phosphorylation hypothesis
C) electron transport hypothesis
D) proton-motive force hypothesis
E) None of the answers is correct.

Question 10

Which enzyme transfers electrons from a membrane-soluble carrier to a water-soluble carrier in the electron-transport process?

A) ATP synthase
B) cytochrome c oxidase
C) NADH-Q oxidoreductase
D) Q-cytochrome c oxidoreductase
E) succinate-Q reductase

Question 11

Which enzyme catalyzes the reduction of oxygen to water?

A) ATP synthase
B) cytochrome c oxidase
C) NADH-Q oxidoreductase
D) Q-cytochrome c oxidoreductase
E) succinate-Q reductase

Question 12

What type of protein makes the outer mitochondrial membrane relatively permeable?

A) proton pump
B) voltage gated transporter
C) ATP-powered pump
D) porin
E) None of the answers is correct.

Question 13

In the glycerol phosphate shuttle,cytoplasmic glycerol phosphate dehydrogenase uses cytoplasmic NADH to reduce _________________ to glycerol-3-phosphate.

Question 14

What organelle is the site of oxidative phosphorylation in eukaryotes?

A) mitochondria
B) chloroplast
C) lysosome
D) endoplasmic reticulum
E) Golgi apparatus

Question 15

Cytochrome ________ is the only water-soluble cytochrome of the electron-transport chain.

Question 16

The transfer of a single electron to O₂ forms the reactive _______________ ion.

Question 17

What process allows cytoplasmic NADH to be reoxidized by O₂ using the electron-transport system?

A) glycerol 3-phosphate shuttle
B) cytochrome c shuttle
C) malate-aspartate shuttle
D) quinone shuttle
E) glycerol 3-phosphate shuttle and malate-aspartate shuttle

Question 18

The unequal distribution of H⁺ across the inner mitochondrial membrane creates a ________________ force.

Question 19

Which of the citric acid cycle enzymes is also part of an electron-transport complex?

A) isocitrate dehydrogenase
B) $\alpha$ -ketoglutarate dehydrogenase
C) succinate dehydrogenase
D) malate dehydrogenase
E) None of the answers is correct.

Question 20

_________________ is a poison because it blocks the flow of electrons from cytochrome c to oxygen.

Question 21

Which of the following does NOT participate in,nor is a component of,the electron-transport chain?

A) lipoic acid
B) nonheme, iron-sulfur proteins
C) FADH₂
D) cytochrome c₁
E) NADH

Question 22

In the Rieske center,the iron-sulfur center is coordinated to the amino acid(s)_______.

A) His
B) Cys
C) His and Cys
D) Cys and Met
E) None of the answers is correct.

Question 23

Electron flow down the electron-transport chain leads to the

A) transport of protons across the inner mitochondrial membrane from inside the matrix to the intermembrane space.
B) transport of protons across the inner mitochondrial membrane from the intermembrane space into the matrix.
C) coupled synthesis of GTP.
D) a dangerous imbalance of K⁺ ions across the mitochondrial membrane.
E) None of the answers is correct.

Question 24

In prokaryotes the site of ATP-synthesizing machinery is

A) the mitochondrial matrix.
B) the outer cell wall.
C) the cytoplasmic membrane.
D) the nucleolus.
E) None of the answers is correct.

Question 25

Explain why less ATP is made from the reoxidation of FADH₂ as compared to NADH.

Question 26

What is the net ATP obtained from one cytoplasmic NADH when it is reoxidized by the electron-transport chain using the glycerol 3-phosphate shuttle?

A) 2.5
B) 1.5
C) 2.0
D) 1.0
E) None of the answers is correct.

Question 27

The energy for ATP synthesis is generated by the movement of protons from the ______________ side of the inner mitochondrial membrane establishing a(an)_____________ gradient.

A) intermembrane; pH
B) intermembrane; electrical potential
C) matrix; sodium ion
D) matrix; pH
E) None of the answers is correct.

Question 28

Which electron carrier has an isoprenoid tail?

A) NADH
B) cytochrome c
C) coenzyme Q
D) FADH^?₂
E) None of the answers is correct.

Question 29

What is the chemical effect of oligomycin on aerobic metabolism?

A) The flow of electrons from NADH to CoQ is blocked.
B) The flow of electrons from Cyt a-a₃ to oxygen is blocked.
C) Oligomycin blocks the proton transfer through F₀ of ATP synthase and therefore blocks the phosphorylation of ADP to form ATP.
D) The transport of ATP out of and ADP into the mitochondria is blocked.
E) Oxidative phosphorylation is uncoupled from electron transport and all the energy is lost as heat.

Question 30

What is the currently accepted model which explains the presence of mitochondria in eukaryotic cells? What is the best evidence which supports this model?

Question 31

What is the reaction of ATP synthase?

A) AMP^3- + 2 HPO₄^2- + H⁺ $\iff$ ATP^4- + H₂O
B) ADP^3- + HPO₄^2-+ H⁺ $\iff$ ATP^4-+ H₂O
C) ADP^3- + HPO₄^2- + 2 H⁺ $\iff$ ATP^4- + H₂O
D) AMP^3- + 2 HPO₄^2- + 2 H⁺ $\iff$ ATP^4- + H₂O
E) None of the answers is correct.

Question 32

In the malate-aspartate shuttle,electrons from NADH are transferred to ________,forming malate.

A) oxaloacetate
B) aspartate
C) acetate
D) glutamate
E) None of the answers is correct.

Question 33

Draw the structure of a mitochondrion and indicate the sites of oxidative phosphorylation and the citric acid cycle.Be sure to label your figure to clearly denote where these processes take place.

Question 34

Which of the following does not pump protons?

A) Complex I
B) Complex II
C) Complex III
D) Complex IV
E) All of the answers are correct.

Question 35

What is the driving force for electron transport through the electron-transport chain?

Question 36

Choose the correct path taken by a pair of electrons as it travels down the electron-transport chain.

A) NADH $\rarr$ Complex I $\rarr$ CoQ $\rarr$ Complex III $\rarr$ Cyt c $\rarr$ Complex IV $\rarr$ O₂
B) FADH₂ $\rarr$ Complex I $\rarr$ CoQ $\rarr$ Complex III $\rarr$ Cyt c $\rarr$ Complex IV $\rarr$ O₂
C) NADH $\rarr$ Complex I $\rarr$ Complex II $\rarr$ Complex III $\rarr$ Cyt c $\rarr$ Complex IV $\rarr$ O₂
D) FADH₂ $\rarr$ Complex III $\rarr$ CoQ $\rarr$ Complex II $\rarr$ Cyt c $\rarr$ Complex IV $\rarr$ O₂
E) None of the answers is correct.

Question 37

Provide a brief description of oxidative phosphorylation.

Question 38

When glucose is totally oxidized to CO₂ and H₂O and the glycerol 3-phosphate shuttle is used,how many ATP molecules are made by oxidative phosphorylation (nonsubstrate-level phosphorylation)relative to the maximum yield?

A) 12 out of 30
B) 26 out of 30
C) 26 out of 32
D) 12 out of 32
E) None of the answers is correct.

Question 39

What is a cytochrome?

A) a protein that transfers electrons and that also contains a heme prosthetic group
B) a chloroplast protein that transfers electrons and that also contains an iron sulfur prosthetic group
C) a protein that pumps ATP and that also contains iron
D) an enzyme that reduces oxygen to water
E) None of the answers is correct.

Question 40

What type of gradient is critical to ATP formation by oxidative phosphorylation?

A) sodium ion
B) chloride ion
C) proton
D) potassium ion
E) None of the answers is correct.

Question 41

What evidence demonstrated the ATP synthase has components that can actually rotate?

Question 42

Describe the major defensive strategy that cells employ to prevent the harmful effects of the reactive oxygen species (ROS)that are inevitably produced during respiration.

Question 43

Discuss the evolution of the cytochrome c protein.

Question 44

In the malate-aspartate shuttle,how is oxaloacetate regenerated since there is no transporter for oxaloacetate across the inner membrane?

Question 45

What are uncoupling agents? Provide an example of when these might be useful.

Question 46

Describe the function of protons in the mechanism of ATP synthesis by the F₁ subunit of ATP synthase.

Question 47

Explain why carbon monoxide is toxic.

Question 48

Give the balanced equation for the net reaction catalyzed by Q-cytochrome c oxido-reducatase.

Question 49

How is oxidative phosphorylation regulated?

Question 50

How does the glycerol 3-phosphate shuttle function?