Chapter 21 The Proton-Motive Force
Matching Questions
Use the following to answer questions 1-10:
Choose the correct answer from the list below. Not all of the answers will be used.
a) Peter Mitchell
b) chemiosmotic theory
c) binding-change
d) loose
e) ATP
f) entropy
g) α subunit
h) tight
i) glycerol 3-phosphate shuttle
j) c ring
k) ATP-ADP translocase
l) malate-aspartate shuttle
m) Sir Hans Krebs
1.
____________ The thermodynamic driving force of ATP synthesis due to pumping of protons.
2.
____________ first described the chemiosmotic hypothesis.
Ans: a
Section: 21.1
3.
____________ is the mechanism for the proton-driven ATP synthesis.
Ans: c
Section: 21.1
4.
____________ Which form of the ATPase subunits is responsible for phosphorylation of ADP?
Ans: h
5.
____________ Rotation of this, driven by proton gradient, powers ATP synthesis.
Ans: j
Section: 21.1
6.
____________ ADP transport into the mitochondria is coupled to the export of __________.
Ans: e
Section: 21.2
Ans: f
Section: 21.3
Chapter 21 The Proton-Motive Force
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7.
____________ Dihydroxyacetone phosphate is part of the ______________ shuttle.
8.
____________ This is the name given to the hypothesis proposed by Peter Mitchell to explain
how ATP synthesis is coupled to electron transport.
Ans: b
Section: 21.1
9.
____________ Atractyloside inhibits this mitochondrial protein.
Ans: k
Section: 21.3
10.
____________ This is a process by which cytoplasmic NADH can be reoxidized by O2 using
the electron-transport system.
Ans: l
Section: 21.2
Fill–in-the-Blank Questions
11.
Transfer of electrons from NADH leads to how many ATP? .
Ans: 2.5 Section: 21.1
12.
membrane protein couples the entry of ADP into the mitochondrial matrix with the exit of
ATP.
Ans: ADP-ATP translocase Section: 21.2
13.
The protein involved with thermogenesis by uncoupling electron transport from oxidative
phosphorylation is .
Ans: uncoupling protein (UCP-1) Section: 21.3
14.
is a molecular assembly in the inner mitochondrial membrane that carries out the synthesis of
ATP.
Ans: F1F0 ATPase, or ATP synthase Section: 21.1
15.
In the glycerol phosphate shuttle, cytoplasmic glycerol phosphate dehydrogenase uses
cytoplasmic NADH to reduce to glycerol-3-phosphate.
Ans: dihydroxyacetone phosphate Section: 21.2
16.
Acceptor control of oxidative phosphorylation means that the rate of respiration depends on the
level of .
Ans: ADP Section: 21.3
17.
is a poison because it blocks the flow of electrons from cytochrome c to oxygen.
Ans: Carbon monoxide (CO), or Cyanide (CN–), or Azide (N3−) Section: 21.3
Ans: i
Section: 21.2
Chapter 21 The Proton-Motive Force
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18.
In the presence of respiration continues but no ATP is formed.
19.
The antibiotic inhibits the flow of protons through ATP synthase.
Ans: oligomycin Section: 21.3
20.
ATP is transported out of the mitochondria by the antiporter .
Ans: ATP-ADP translocase Section: 21.2
Multiple-Choice Questions
21.
What type of gradient is critical to ATP formation by oxidative phosphorylation?
A)
sodium ion
D)
potassium ion
B)
chloride ion
E)
None of the above.
C)
proton
Ans: C Section: Introduction
22.
When glucose is totally oxidized to CO2 and H2O, how many ATP molecules are made by
oxidative 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 38
E)
None of the above.
Ans: B Section: 21.3
23.
What is the chemical effect of rotenone 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 are blocked.
E)
Oxidative phosphorylation is uncoupled from electron transport and all the energy is lost
as heat.
Ans: A Section: 21.3
24.
The subunit of the ATPase embedded in the inner mitochondrial membrane is the __________.
A)
anchor subunit
B)
membrane-c ring subunit
C)
F0 subunit
D)
F1 subunit
E)
Fm subunit
Ans: C Section: 21.1
Ans: uncouplers Section: 21.3
Chapter 21 The Proton-Motive Force
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25.
The F1 component of ATP synthase is composed of _________.
A)
three α subunits
B)
three β subunits
C)
a Δ subunit
D)
All of the above.
E)
None of the above.
26.
The proton motive force consists of _____________.
A)
a chemical gradient
D)
A and B.
B)
a proton gradient.
E)
A, B, and C.
C)
an electron gradient
Ans: D Section: 21.1
27.
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 mitochondiral membrane.
E)
None of the above.
Ans: A Section: 21.1
28.
How does the rotation of the c ring lead to ATP synthesis?
A)
The c ring is linked tightly to the gamma and epsilon subunits in the stalk of F1.
B)
The c ring interacts with the beta subunit.
C)
The gamma subunit rotates with proton gradient formation inducing the binding-change
mechanism.
D)
All of the above.
E)
None of the above.
Ans: D Section: 21.1
29.
What are the driving force (energetic) costs for the ATP-ADP translocase?
A)
entropy – concentration gradient of ATP
B)
membrane potential from electron transport
C)
active transport by Na-K ATPase
D)
All of the above.
E)
None of the above.
Ans: B Section: 21.1
30.
A diet pill that acts to increase oxygen consumption and a high amount of electron transport
without ATP production is likely what kind of compound?
A)
uncoupler
B)
ATP synthase activator
C)
site I inhibitor
D)
site II activator
E)
cyanide
Ans: A Section: 21.3
Ans: D Section: 21.1
Chapter 21 The Proton-Motive Force
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31.
What is the reaction of ATP synthase?
A)
AMP3− + 2 HPO42− + H+ ATP4− + H2O
B)
ADP3− + HPO42− + H+ ATP4− + H2O
C)
ADP3− + HPO42− + 2H+ ATP4− + H2O
D)
AMP3− + 2 HPO42− + 2H+ ATP4− + H2O
E)
None of the above.
32.
What is the net ATP obtained from one cytoplasmic NADH when it is oxidized 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 above.
Ans: B Section: 21.3
33.
In the malate-aspartate shuttle, electrons from NADH are transferred to ________, forming
malate.
A)
oxaloacetate
D)
glutamate
B)
aspartate
E)
None of the above.
C)
acetate
Ans: A Section: 21.3
34.
Suppose there is a mutation in the c subunit of ATP synthase, such that the glutamate found in
the middle of one of the membrane spanning helices is converted to a valine. What is likely to
be the effect on ATP synthesis and why?
A)
No effect. The middle of the helix is in contact with the hydrophobic center of the lipid
bilayer and the valine is readily soluble in lipid.
B)
No effect. The valine side chain is shorter than the glutamate side chain, so it causes no
change in the secondary structure of the helix.
C)
Inhibit ATP synthesis. Valine cannot bind a proton, so there will be no proton flow
through the inner membrane.
D)
Inhibit ATP synthesis. Because valine is hydrophobic, the α subunit will move in the
reverse direction, causing the hydrolysis of ATP, not synthesis.
E)
Increase ATP synthesis. Because the valine side chain is hydrophobic, the α subunit can
move easily without regard to oxidative processes.
Ans: C Section: 21.1
35.
Why is it not surprising that substances such as intermediates for the citric acid cycle, protons,
inorganic phosphate, nucleotide phosphates, and many others have their transport across the
inner membrane regulated?
A)
Regulated transport allows for more effective substrate cycling.
B)
Ultimately all electrons flow into the electron-transport chain, which regulates electron
flow from the matrix to the inner membrane space.
C)
The experiment where bacteriorhodopsin and ATP synthase were inserted into
reconstituted vesicles showed that biochemically, membranes control the movement of
electrons in the respiratory chain.
D)
Many of the reactions in the citric acid cycle and ATP synthesis are driven by
accessibility of substrates and differential gradients across the inner membrane.
E)
It is necessary to segregate the enzymes capable of substrate level phosphorylation during
anaerobic respiration.
Ans: D Section: 21.3
Ans: B Section: 21.1
Chapter 21 The Proton-Motive Force
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Short-Answer Questions
36.
Provide a brief description of oxidative phosphorylation.
37.
What additional free energy driven processes are powered by a proton gradient?
Ans:
Active transport, flagellar rotation, NADPH synthesis, and heat production are all driven
by a proton gradient.
Section: 21.3 and Figure 21.21
38.
Explain why less ATP is made from the reoxidation of FADH2 as compared to NADH.
catalyzed by complex II, complex III, and complex IV, fewer protons are pumped out of
the matrix as compared to NADH. Thus, fewer ATP molecules are ultimately made.
Section: 21.3
39.
What is the actual function of the protons in the synthesis of ATP by F0F1 ATP synthase?
enzyme causes a conformational change that releases the bound ATP. The role of the proton
gradient is not to form ATP but to release it from the synthase.
Section: 21.1
40.
What was the proof that the ATP synthase was rotating?
a nickel coated slide, and using another fluorescent tag linked to the subunit, the
rotation could be observed using a fluorescent microscope.
Section: 21.1 and Figure 21.7
41.
How does the glycerol 3-phosphate shuttle function?
then transfers the electrons to FAD of glycerol-3-phosphate dehydrogenase located in the
inner membrane. The FADH2 then transfers the electrons to Q.
Section: 21.3
42.
In the malate-aspartate shuttle, how is oxaloacetate regenerated even though there is no
transporter for oxaloacetate across the inner membrane?
oxaloacetate reactions require glutamate and -ketoglutarate.
Section: 21.3
Ans:
It is the process in which ATP is formed due to the transfer of electrons from NADH or
Section: Introduction
Chapter 21 The Proton-Motive Force
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43.
How is oxidative phosphorylation regulated?
44.
What are uncouplers? Provide an example of when this might be useful.
one example provided (due to the uncoupler UCP-1).
Section: 21.3
45.
Explain why carbon monoxide is toxic.
occur. Thus, energy production ceases.
Section: 21.3
46.
What is the mechanism for nonshivering thermogenesis?
(UCP-1). UCP-1 generates heat by uncoupling respiration and ATP synthesis.
Section: 21.3
47.
What is the relationship between obesity and UCP-1?
Ans:
Obesity leads to a decrease in brown fat adipose, a tissue rich in UCP-1.
Section: 21.3
48.
What is the IF1 protein and what is its protective role in tissues?
hydrolytic activity.
Section: 21.3
49.
Would you expect polar bears to have a rich store of brown adipose? Why or why not?
from dormancy.
Section: 21.3
referred to as acceptor control.
Section: 21.3
Chapter 21 The Proton-Motive Force
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50.
What is the difference between a respiratory inhibitor and a decoupling agent? Describe an
experiment that could determine the difference.
synthesis stops.