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Biochemistry > Exam 3 practice questions > Flashcards

Exam 3 practice questions Flashcards

1
Q 
Which of the following occurs when the catalytic subunit of ATP synthase is in the loose
state?
a. ADP and Pi bind.
b. ADP and Pi are converted to ATP.
c. ATP is hydrolyzed
d. ATP is released.
e. None of the above
A

A

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2
Q

The imbalance of protons across the inner mitochondrial membrane is referred to as _____.

a. the protonmotive force
b. the chemiosmotic force
c. the electron transport force
d. the ATP synthase force
e. the proton gradient force

A

A

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3
Q 
What transport system moves activated fatty acids from the cytosol to the mitochondrial
matrix?
a. triacylglycerol shuttle
b. glycerol phosphate shuttle
c. acyl adenylate shuttle
d. lipoprotein shuttle
e. carnitine shuttle
A

E

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4
Q

Which of the following is the active donor of carbon units in fatty acid biosynthesis?

a. acetyl CoA
b. malonyl CoA
c. palmitic acid
d. propionyl CoA
e. Ceramides

A

B

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5
Q

Which of the following terms describes all glycerophospholipids?

a. Zwitterionic
b. Amphipathic
c. Nonpolar
d. Amphoteric
e. none of the above

A

B

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6
Q

Which statement concerning phospholipid synthesis is true?

a. Addition of polar “head groups” to diacylglycerol usually involves CDP derivatives.
b. Addition of polar “head groups” to diacylglycerol usually involves UDP adducts.
c. Addition of fatty acyl “tails” to glycerol usually involves CDP adducts.
d. Addition of fatty acyl “tails” to glycerol usually involves UDP adducts.
e. None of the above is true

A

A

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7
Q

Which of the following explains how phosphatidylserine is synthesized?

a. Serine displaces the ethanolamine from a phosphatidylethanolamine .
b. Serine reacts with a diacylglycerol pyrophosphate.
c. CDP-serine reacts with diacylglycerol
d. Serine reacts with a CDP-diacylglycerol.
e. The ethanolamine group of phosphatidylethanolamine is carboxylated to form serine.

A

A

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8
Q 
Digestion of triacylglycerols is aided by the cholesterol derivatives synthesized by the liver
known as \_\_\_\_\_.
a. bile acids
b. Lipoproteins
c. Lanosterols
d. Chylomicrons
e. colipases
A

A

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9
Q

Evidence for the counterclockwise rotation of ATP synthase was found using:

a. Streptavidin tag
b. Fluorescent Actin tail
c. Immunohistochemical staining
d. Biotin
e. NMR microscopy

A

A, B, D

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10
Q 
In the synthesis of a C16 (palmitate) fatty acid, \_\_\_\_\_\_ NADPH, \_\_\_\_\_ ATP and \_\_\_\_\_
acetyl-CoA are used
a. 14, 7, 8
b. 15, 8, 7
c. 14, 8, 7
d. 15, 7, 8
e. 14, 7, 7
A

A

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11
Q

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 because of inhibition of the CoQ subunit of ATP synthase.
c. ATP production would be reduced because of a decrease in the number of protons pumped out of the mitochondrial matrix.
d. ATP production would be halted completely because of the block in electron transport through the electron transport chain.
e. ATP production would be maintained at the normal rate because of functional overlap between Complex I and Complex II.

A

C

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12
Q

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

A

A

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13
Q

Fatty acid synthesis requires both acetyl-CoA and _____ as initiator molecules.

A

malonyl-CoA

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14
Q

Acyl carrier protein (ACP) contains a _____ prosthetic group.

A

phosphopantetheine

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15
Q 
Which of the following alcohols is esterified to the phosphate group of
glycerophospholipids?
a. Choline
b. Ethanolamine
c. Glycerol
d. Serine
e. all of the above
A

E

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16
Q

Which two molecules are used in the synthesis of sphingosine?

a. arachidonic acid and serine
b. stearic acid and isoprene
c. palmitoyl-CoA and choline
d. linoleoyl-CoA and isoprene
e. palmitoyl-CoA and serine

A

E

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17
Q

What is used to activate phosphoethanolamine prior to reaction with a diacylglycerol?

a. ATP
b. CTP
c. GTP
d. TTP
e. UTP

A

B

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18
Q

Which of the following accurately ranks lipoproteins from highest to lowest density?

a. chylomicrons > HDL > LDL > IDL > VLDL
b. HDL > IDL > LDL > VLDL > chylomicrons
c. HDL > LDL > IDL > VLDL > chylomicrons
d. chylomicrons > VLDL > IDL > LDL > HDL
e. VLDL > IDL > LDL > HDL > chylomicrons

A

C

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19
Q

Cells may take up _____ by receptor-mediated endocytosis

A

LDL

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20
Q

The breakdown of glycogen produces G1P. Which of the following is false regarding
G1P?
a. It is involved in the use of fructose by glycolysis in the liver.
b. It is involved in the use of fructose by glycolysis in the muscle.
c. It is involved in the use of galactose by glycolysis.
d. It is converted to G6P by phosphoglucoisomerase (PGI). It is produced as an
intermediate in the central glycolytic sequence

A

D

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21
Q 
In glycogen synthesis, what is the intermediate between glucose-1-phosphate and
glycogen?
a. Glucose-6-phosphate
b. Glucose-1,6-bisphosphate
c. UTP-glucose
d. UDP-glucose
e. none of the above
A

D

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22
Q

Which enzyme below is not required for the synthesis of branched glycogen?

a. glycogen phosphorylase
b. glycogen synthase
c. branching enzyme
d. Phosphoglucomutase
e. All are required for the synthesis of glycogen.

A

A

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23
Q

A deficiency in muscle glycogen phosphorylase would result in _____.

a. normal muscle glycogen structure
b. abnormal muscle glycogen structure
c. elevated muscle glycogen levels
d. A and C
e. B and C

A

D

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24
Q

Patient “G” has a glycogen storage disease that results in decreased muscle glycogen
levels. Muscle biopsies indicate poor glycogen structure in the muscle. Which of the
following enzymes might be related to the cause?
a. muscle debranching enzyme
b. muscle glycogen phosphorylase
c. liver debranching enzyme
d. muscle glycogen synthase
e. liver glycogen synthase

A

D

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25
Q

Bacterial cell walls are made of _____.

a. Pectin
b. chondroitin sulfate
c. Peptidoglycans
d. keratin sulfate
e. Heparin

A

C

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26
Q

What is the name for the process that produces ATP from ADP in glycolysis?

a. substrate-level phosphorylation
b. oxidative phosphorylation
c. Autophosphorylation
d. glycolytic phosphorylation
e. cytosolic phosphorylation

A

A

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27
Q

Glyceraldehyde-3-PO4 is oxidized to _____, which can transfer a phosphate to _____.

a. Phosphoenolpyruvate; ADP
b. Phosphoenolpyruvate; AMP
c. 1,3-bisphosphoglycerate; ADP
d. 1,3-bisphosphoglycerate; AMP
e. 3-phosphoglycerate; ADP

A

C

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28
Q 
Which of the following contains a bond that is used for a substrate-level phosphorylation
in glycolysis?
a. Fructose-1,6-bisphosphate
b. 1,3-bisphosphoglycerate
c. acetyl phosphate
d. 2,3-bisphosphoglycerate
e. 1-phosphoglycerate
A

B

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29
Q

The use of fructose in glycolysis in the liver _____.

a. requires UDP-glucose
b. requires one extra ATP
c. uses GTP rather than ATP
d. May bypass phosphofructokinase (PFK) regulation
e. enters glycolysis as fructose bisphosphate (FBP)

A

D

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30
Q 
What pathway is used to make glucose from other metabolites such as pyruvate or
lactate?
a. Glycogen synthesis
b. glycogen degradation
c. Glycolysis
d. pentose phosphate pathway
e. Gluconeogenesis
A

E

31
Q

Which of the following pyruvate dehydrogenase enzymes is correctly paired with the coenzyme that is associated with it?

A

C

32
Q

What type of bond forms when the hydroxyethyl group is transferred to lipoamide?

a. Ester
b. Amide
c. Thioester
d. Anhydride
e. none of the above

A

C

33
Q

Condensation of _____ with oxaloacetate yields citrate.

a. acetyl-CoA
b. Α-ketoglutarate
c. Isocitrate
d. Citrophosphate
e. Oxalosuccinate

A

A

34
Q

The isomerization of citrate to isocitrate _____.
a. is the reaction of the citric acid cycle that occurs spontaneously without
enzymatic catalysis
b. protects cells from the toxic effects of arsenite ion
c. converts a tertiary alcohol that cannot easily be oxidized to a secondary alcohol
that can be oxidized
d. is one major regulatory step for the citric acid cycle because it functions as a
rate-limiting step
e. A and B

A

C

35
Q

The reaction catalyzed by _____ requires an enzyme-bound flavin coenzyme.

a. isocitrate dehydrogenase
b. a-ketoglutarate dehydrogenase
c. succinyl-CoA synthetase
d. succinate dehydrogenase
e. malate dehydrogenase

A

D

36
Q

Which of the following enzymes of the citric acid cycle is inhibited by ATP?

a. citrate synthase
b. isocitrate dehydrogenase
c. a-ketoglutarate dehydrogenase
d. succinyl-CoA synthetase
e. A and B

A

B

37
Q

Which of the following is an anaplerotic reaction that is often used in the cell?

a. conversion of pyruvate to acetyl-CoA
b. conversion of a-ketoglutarate to glutamic acid
c. conversion of citrate to oxaloacetate and acetyl-CoA
d. conversion of pyruvate to oxaloacetate
e. conversion of succinyl-CoA to heme

A

D

38
Q

In the electron transport chain, electrons are passed from redox center to redox center
____.
a. Spontaneously because of the redox potential gradient
b. in an ATP dependent fashion
c. because of the addition of free energy
d. Because of the proton gradient
e. with the assistance of a carrier protein

A

A

39
Q

In eukaryotes, the citric acid cycle occurs in the _____ and therefore requires that
reactants of the citric acid cycle be transported from the _____.
a. cytosol; mitochondrial matrix
b. mitochondrial matrix; cytosol
c. endoplasmic reticulum; mitochondrial matrix
d. inner mitochondrial membrane; mitochondrial matrix
e. outer mitochondrial membrane; cytosol

A

B

40
Q

Which of the prosthetic groups listed can accept or donate either one or two electrons
because of the stability of the semiquinone state?
a. Cytochrome c
b. NADH
c. Ubiquinone
d. [2Fe-2S]
e. Rieske center

A

C

41
Q 
Complex III accepts electrons from \_\_\_\_\_ and transfers them to \_\_\_\_\_.
A) cytochrome c; cytochrome a
B) ubiquinol; cytochrome c
C) ubiquinone; cytochrome c
D) ubiquinol; cytochrome b
E) ubiquinone; cytochrome a
A

B

42
Q 
What cellular location contains pyruvate dehydrogenase and most of the citric acid cycle
enzymes?
A) cytosol
B) mitochondrial matrix
C) inner mitochondrial membrane
D) mitochondrial inter-membrane space
E) outer mitochondrial membrane
A

B

43
Q

Which of the following statements about reduction potentials is FALSE?
A) It describes the tendency of the oxidized form of a species to be reduced.
B) The more negative the value the greater the tendency to be reduced.
C) The actual reduction potential depends on the concentration of species.
D) Both B and C are false.
E) None of the above are false.

A

B

44
Q 
Under anaerobic conditions in skeletal muscle, pyruvate is converted into \_\_\_\_\_.
A) ethanol and CO2
B) propionate
C) acetyl-CoA
D) lactate
E) alanine
A

D

45
Q

Degradation of proteins within a cell can occur within the _____ or by use of _____.
A) endoplasmic reticulum; protease enzymes chymotrypsin and trypsin
B) Golgi apparatus; protease enzymes chymotrypsin and trypsin
C) endoplasmic reticulum; a proteasome
D) lysosome; a proteasome
E) mitochondria; ubiquitin

A

D

46
Q 
Any sugar that has a free aldehyde group is called a(n) \_\_\_\_\_.
A) reducing sugar
B) non-reducing sugar
C) ketose
D) aldohexose
E) alditol
A

A

47
Q 
What type of bond forms when the hydroxyethyl group is transferred to lipoamide?
A) ester
B) amide
C) thioester
D) anhydride
E) none of the above
A

C

48
Q 
Bacterial cell walls are made of \_\_\_\_\_.
A) pectin
B) chondroitin sulfate
C) peptidoglycans
D) keratin sulfate
E) heparin
A

C

49
Q 
The initial addition of oligosaccharides of N-glycosylated proteins occurs in the \_\_\_\_\_.
A) lysosome
B) Golgi apparatus
C) endoplasmic reticulum
D) vacuole
E) cytoplasm
A

C

50
Q 
The coenzyme \_\_\_\_\_ is the oxidizing agent in glycolysis.
A) ADP
B) thiamine pyrophosphate
C) NAD+
D) FAD
E) biotin
A

C

51
Q

In the citric acid cycle, what reduced cofactors are derived from the oxidation of one
molecule of acetyl-CoA to two molecules of CO2?
A) 2 NADH and 1 QH2
B) 3 NADH and 1 QH2
C) 2 NADH and 2 QH2
D) 3 NADH and 2 QH2
E) 4 NADH and 2 QH2

A

B

52
Q 
How many protons are transported from the matrix to the intermembrane space by
Complex I?
A) 0
B) 2
C) 4
D) 6
E) 8
A

C

53
Q 
When a reaction is at equilibrium, the ΔG is equal to \_\_\_\_\_.
A) 1
B) 0
C) -1
D) ΔG°"
E) none of the above
A

B

54
Q 
Which two monosaccharides seen below are epimers?
A) A and B
B) B and C
C) B and D
D) C and D
E) A and D
A

E

55
Q 
Which of the following enzymes involved in gluconeogenesis reverses the reaction of
hexokinase?
A) fructose bisphosphatase
B) phosphofructokinase
C) hexokinase (reversible reaction)
D) glucose-6-phosphatase
E) phosphoglycerate mutase
A

D

56
Q

Energy is generated during _____, the breakdown of larger molecules into smaller while
energy is consumed during _____, the building of larger molecules from smaller ones.
A) reduction reactions; oxidation reactions
B) autotrophic reactions; heterotrophic reactions
C) catabolic reactions; anabolic reactions
D) hydrolysis reactions; condensation reactions
E) none of the above

A

C

57
Q 
. Which of the following is a potent activator of phosphofructokinase in mammals?
A) fructose-6-phosphate
B) glucose-6-phosphate
C) fructose-2,6-bisphosphate
D) fructose-1,6-bisphosphate
E) glyceraldehyde-3-phosphate
A

C

58
Q

How many electrons are transferred from one acetyl group when it is converted to two
carbon dioxide molecules in the citric acid cycle?
A) 2
B) 4
C) 6
D) 8
E) 10

A

D

59
Q 
The bulk of triacylglycerols in the human body are stored in \_\_\_\_\_.
A) liver cells
B) adipocytes
C) muscle cells
D) nerve cells
E) lipoproteins
A

B

60
Q 
Complex IV uses \_\_\_\_\_ and \_\_\_\_\_ ions to reduce oxygen to water.
A) manganese; iron
B) copper; iron
C) manganese; copper
D) zinc; copper
E) iron; zinc
A

B

61
Q 
Which enzyme of the pyruvate dehydrogenase complex is responsible for regenerating
an oxidized lipoamide cofactor?
A) E1
B) E2
C) E3
A

C

62
Q

During glycolysis, the steps between glucose and the formation of the triose phosphates
A) produce two ADP and two NAD+ molecules
B) produce two ATP and two NADH molecules
C) consume two NADH molecules
D) consume two ATP molecules
E) consume two ATP and two NADH molecules

A

D

63
Q

Which of the following best explains why the formation of UDP-glucose from glucose-1-phosphate in the liver and muscle is energetically favorable?
A) ΔG°’ for the reaction glucose-1-phosphate + UTP → UDP-glucose + PPi is very positive.
B) ΔG°’ for the reaction PPi→ 2Pi is very positive.
C) ΔG°’ for the reaction PPi→ 2Pi is very negative.
D) ΔG°’ for the reaction glucose-1-phosphate + UTP → UDP-glucose + PPi is very negative.

A

C

64
Q 
In the muscle, when a residue of glucose is cleaved from glycogen and converted to pyruvate via glycolysis, what is the net ATP production (beginning with glycogenolysis)?
A) 1
B) 2
C) 3
D) 4
E) 5
A

C

65
Q

Unlike proteins and oligonucleotides, polysaccharides _____.
A) are readily metabolized in the absence of specialized enzymes
B) often have branched structures
C) are achiral
D) are always completely water-soluble
E) are components of every known living organism

A

B

66
Q

Which of the following is correct regarding metabolic pathways?
A) most pathways are isolated from other pathways
B) the activity of most pathways is not regulated
C) all cells within a multi-cellular organism contain the same pathways
D) anabolic pathways never occur at the same time as catabolic pathways
E) none of the above are correct

A

E

67
Q 
Which compound is in the highest oxidation state?
A) carbon monoxide (CO)
B) methane (CH4)
C) methanol (CHOH)
D) carbon dioxide (CO2)
E) acetic acid (CH3COOH)
A

D

68
Q 
Glyceraldehyde is oxidized to \_\_\_\_\_ which can transfer a phosphate to \_\_\_\_\_.
A) phosphoenolpyruvate; ADP
B) phosphoenolpyruvate; AMP
C) 1,3-bisphosphoglycerate; ADP
D) 1,3-bisphosphoglycerate; AMP
E) 3-phosphoglycerate; ADP
A

C

69
Q 
How many molecules of NADPH are produced per glucose molecule processed by the
pentose phosphate pathway?
A) 1
B) 2
C) 3
D) 4
A

B

70
Q 
\_\_\_\_\_\_ is the first compound that is oxidized in the citric acid cycle.
A) oxaloacetate
B) isocitrate
C) malonate
D) malate
E) α-ketoglutarate
A

B

71
Q

In the event that NADPH is needed but ribose is not, which of the following is an end
product of the pentose phosphate pathway?
A) ribulose-5-phosphate
B) dihydroxyacetone phosphate
C) fructose-1,6-bisphosphate
D) 1,3-bisphosphoglycerate
E) glyceraldehyde-3-phosphate

A

E

72
Q 
Which of the following is mobilized for energy use by a phosphorolysis reaction rather
than by hydrolysis?
A) glycogen
B) protein
C) triacylglycerols
D) polynucleotides
E) cholesterol esters
A

A

73
Q 
What would be the predicted energy yield of ATP from glycolysis in a patient with a
defect in triosephosphate isomerase?
A) 4 ATP
B) 3 ATP
C) 2 ATP
D) 1ATP
E) 0 ATP
A

E

Biochemistry (13 decks)

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