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Biochemistry > Glycolysis > Flashcards

Glycolysis Flashcards

1
Q

The amino acid cysteine is important in adding a second phosphate
to glyceraldehyde phosphate in the glyceraldehyde-3-phosphate
dehydrogenase reaction.
a. True
b. False

A

a. True

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2
Q

Which of the following glycolytic enzymes forms a mixed anhydride
from phosphoric acid?
a. hexokinase.
b. phosphofructokinase.
c. glyceraldehyde-3-phosphate dehydrogenase.
d. phosphoglycerate kinase.
e. pyruvate kinase.

A

c. glyceraldehyde-3-phosphate dehydrogenase.

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3
Q

How many steps in glycolysis have ATP as a substrate or
product?
a. zero
b. 1
c. 2
d. 4
e. 6
f. none of these

A

d. 4

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4
Q

Which of the following terms describes an enzyme that transfers
a phosphate group from ATP to a substrate?
a. kinase
b. isomerase
c. mutase
d. dehydrogenase

A

a. kinase

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5
Q

The order of compounds in the conversion of glucose to pyruvic
acid is as follows: (PEP = phosphoenolpyruvate)
a. Fructose-bisphosphate, fructose-6-phosphate, 1,3-phosphoglyceric
acid, 3-phosphoglyceric acid, PEP.
b. Fructose-6-phosphate, fructose-bisphosphate, PEP, 1,3-phosphoglyceric
acid, 3-phosphoglyceric acid.
c. Fructose-6-phosphate, fructose-bisphosphate, 1,3-phosphoglyceric
acid, 3-phosphoglyceric acid, PEP.
d. Fructose-6-phosphate, fructose-bisphosphate, 3-phosphoglyceric
acid, 1,3-phosphoglyceric acid, PEP.
e. Fructose-bisphosphate, fructose-6-phosphate, 3-phosphoglyceric
acid, 1,3-phosphoglyceric acid, PEP.

A

c. Fructose-6-phosphate, fructose-bisphosphate, 1,3-phosphoglyceric
acid, 3-phosphoglyceric acid, PEP.

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6
Q
  1. Which enzyme is the key regulatory enzyme in glycolysis?
    a. Glyceraldehyde-3-phosphate dehydrogenase
    b. Enolase
    c. Phosphofructokinase
    d. Aldolase
A

c. Phosphofructokinase

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7
Q

The equilibrium for isomerization of dihydroxyacetone phosphate
to glyceraldehyde-3-phosphate is favored because
a. the standard free energy is negative
b. glyceraldehyde-3-phosphate is being continuously drained off
for the subsequent reaction in the glycolytic pathway
c. the value of the equilibrium constant favors the reaction
d. it is driven by the hydrolysis of ATP

A

b. glyceraldehyde-3-phosphate is being continuously drained off
for the subsequent reaction in the glycolytic pathway

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8
Q

The step that commits the cell to metabolize glucose is catalyzed
by
a. hexokinase.
b. phosphoglucomutase.
c. aldolase.
d. phosphofructokinase

A

d. phosphofructokinase

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9
Q

Which of the following enzymes interconverts an aldose and a
ketose?
a. kinase
b. isomerase
c. mutase
d. dehydrogenase
e. phosphorylase

A

b. isomerase

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10
Q

The nicotinamide-binding region in glyceraldehyde-3-phosphate
dehydrogenase is similar to all other NAD binding domains.
a. True
b. False

A

a. True

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11
Q

Thiamine pyrophosphate is a coenzyme
a. frequently encountered in oxidation-reduction reactions.
b. required for the phosphorylation of ADP.
c. involved in transfers of two-carbon groups.
d. involved in transfers of one-carbon groups.

A

c. involved in transfers of two-carbon groups.

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12
Q

When humans consume ethanol, the first step in its metabolism
is:
a. conversion to lactate
b. conversion to acetaldehyde
c. conversion to acetone
d. production of fat

A

b. conversion to acetaldehyde

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13
Q

How many enzymes of glycolysis are control points for the
pathway?
a. 1
b. 2
c. 3
d. 4
e. All the enzymes serve as control points.

A

c. 3

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14
Q

The isomerization of dihydroxyacetone phosphate to give
glyceraldehyde 3-phosphate
a. is catalyzed by the enzyme triose phosphate isomerase.
b. requires several enzymes.
c. requires coenzyme A.
d. requires thiamine pyrophosphate.

A

a. is catalyzed by the enzyme triose phosphate isomerase.

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15
Q

Consider the following information:

phosphoenolpyruvate ’ pyruvate ”G°’ = 61.9 kJ/mol
ADP + Pi ’ ATP ”G°’ = +30.5 kJ/mol

How many molecules of ATP might theoretically have been produced
when coupled to the conversion of one molecule phosphoenolpyruvate
to pyruvate?
a. 1
b. 2
c. 3
d. 4

A

b. 2

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16
Q

Which of the following is true about phosphofructokinase?
a. It is made of a single polypeptide chain
b. It is found in the muscle only
c. It is made up of four subunits, potentially of two different types
d. A person who lacks the M subunit does not have the glycolytic
pathway

A

c. It is made up of four subunits, potentially of two different types

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17
Q

During anaerobic metabolism in yeast, the carbons of glucose
end up in
a. CO2.
b. ethanol.
c. lactic acid.
d. both CO2 and ethanol.
e. all of these

A

d. both CO2 and ethanol.

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18
Q

The percentage of energy captured as ATP during the conversion of glucose to lactate is closest to
a. 10%.
b. 30%.
c. 50%.
d. 75%.
e. 90%.

A

b. 30%.

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19
Q

Which of the following enzymes catalyzes a dehydration reaction?
a. Glyceraldehyde-3-phosphate dehydrogenase
b. Enolase
c. Phosphofructokinase
d. Aldolase

A

b. Enolase

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20
Q

Which of the following enzymes relies on thiamine pyrophosphate
as a cofactor?
a. pyruvate decarboxylase
b. pyruvate kinase
c. lactate dehydrogenase
d. enolase

A

a. pyruvate decarboxylase

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21
Q

Methanol is extremely toxic, but not directly. In the body, it
is converted into formaldehyde; that’s what’s actually the poison.
What kind of enzyme catalyses this conversion?
a. a kinase
b. an isomerase
c. a mutase
d. a dehydrogenase

A

d. a dehydrogenase

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22
Q

Which enzyme catalyzes the reaction shown?
a. an epimerase
b. an isomerase
c. a mutase
d. a dehydrogenase

A

b. an isomerase

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23
Q

In glycolysis, ATP is synthesized by
a. substrate-level phosphorylation.
b. oxidative phosphorylation.
c. photophosphorylation.
d. both substrate-level and oxidative phosphorylation.
e. all three of the above methods.

A

a. substrate-level phosphorylation

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24
Q

What is the relationship between glycolysis and cancer?
a. cancer cells lack a glycolytic pathway
b. cancer cells use a modified version of glycolysis
c. cancer cells exhibit a much higher level of anaerobic glycolysis than normal cells
d. none of these

A

c. cancer cells exhibit a much higher level of anaerobic glycolysis than normal cells

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25
Q

The equilibrium for the formation of glyceraldehyde-3-phosphate
from dihydroxyacetone phosphate is driven by
a. the negative free energy change for the reaction.
b. having the product of the reaction continuously consumed.
c. coupling to ATP hydrolysis.
d. none of these

A

b. having the product of the reaction continuously consumed.

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26
Q

During glycolysis, ATP is synthesized from ADP and a phosphate
group transferred from an acid anhydride.
a. True
b. False

A

a. True

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27
Q

Which of the following enzymes forms a thioester using a
cysteine residue as a key intermediate?
a. hexokinase
b. triose phosphate isomerase
c. glyceraldehyde-3-phosphate dehydrogenase
d. enolase

A

c. glyceraldehyde-3-phosphate dehydrogenase

28
Q

An enzyme not involved in the control of glycolysis is
a. hexokinase.
b. triose phosphate isomerase.
c. pyruvate kinase.
d. phosphofructokinase.

A

b. triose phosphate isomerase.

29
Q

During anaerobic metabolism in red blood cells, the carbons
of glucose end up in
a. CO2.
b. ethanol.
c. lactic acid.
d. both CO2 and ethanol.
e. all of the above.

A

c. lactic acid.

30
Q

Enolase catalyzes
a. the cleavage of fructose bisphosphate into two 3-carbon units.
b. the dehydration of 2-phosphoglycerate.
c. the conversion of phosphoenolpyruvate to pyruvate.
d. the conversion of glucose-6-phosphate to fructose-6-phosphate.

A

b. the dehydration of 2-phosphoglycerate.

31
Q

Fetal alcohol syndrome
a. can be prevented by administering large doses of vitamin B1
to pregnant women
b. can be prevented by administering large doses of the vitamin
niacin (nicotinic acid) to pregnant women
c. can be reversed by administering acetaldehyde
d. can be detected by measuring the level of acetaldehyde in the bloodstream of a pregnant woman

A

d. can be detected by measuring the level of acetaldehyde in the bloodstream of a pregnant woman

32
Q

The reaction of fructose 1,6-bisphosphate to give glyceraldehyde-
3-phosphate and dihydroxyacetone phosphate is an example
of
a. a reverse aldol condensation.
b. hydrolysis.
c. oxidation.
d. dehydration.

A

a. a reverse aldol condensation.

33
Q

The phosphorylation of fructose 6-phosphate to fructose-
1,6-bisphosphate is the committed step in glycolysis because
a. it is the rate-limiting step.
b. it is the most strongly exergonic step in the pathway.
c. fructose 1,6-bisphosphate can undergo no other reactions than those of glycolysis.
d. two phosphate groups are involved.

A

c. fructose 1,6-bisphosphate can undergo no other reactions than those of glycolysis

34
Q

Which of the following is not an end product of glucose metabolism
via either aerobic or anaerobic means?
a. ethanol
b. carbon dioxide
c. lactate
d. fructose
e. all of these are end products of glucose metabolism

A

d. fructose

35
Q

Which of the following sugars can be a substrate for hexokinase?
a. glucose
b. fructose
c. mannose
d. all of these
e. none of these

A

d. all of these

36
Q

Which of the following enzymes of glycolysis is not involved in
regulation of the pathway?
a. Hexokinase
b. Phosphofructokinase
c. Aldolase
d. Pyruvate kinase
e. All of these proteins regulate glycolysis.

A

c. Aldolase

37
Q

Which of the following enzymes catalyzes the cleavage of
fructose bisphosphate into two 3-carbon units?
a. Aldolase
b. Enolase
c. An isomerase
d. A mutase
e. None of these enzymes carries out that reaction.

A

a. Aldolase

38
Q

What kind of enzyme catalyzes the reaction shown?
a. an epimerase
b. an isomerase
c. a mutase
d. a dehydrogenase

A

d. a dehydrogenase

39
Q

Which of the following is required for substrate-level phosphorylation?
a. The substrate must contain multiple phosphate groups.
b. Molecular oxygen must present.
c. The standard free energy of the hydrolysis reaction is more
negative than that for hydrolysis of the new phosphate compound
being formed.
d. All of the above are necessary for substrate-level phosphorylation.

A

c. The standard free energy of the hydrolysis reaction is more
negative than that for hydrolysis of the new phosphate compound
being formed.

40
Q

Which of the following enzymes of anaerobic metabolism is
not tetrameric?
a. Hexokinase
b. Phosphofructokinase
c. Pyruvate kinase
d. Lactate Dehydrogenase

A

a. Hexokinase

41
Q

The phosphorylation of glucose to glucose 6-phosphate
a. is so strongly exergonic that it does not require a catalyst.
b. is an exergonic reaction not coupled to any other reaction.
c. is an endergonic reaction that takes place because it is coupled
to the exergonic hydrolysis of ATP.
d. is an exergonic reaction that is coupled to the endergonic
hydrolysis of ATP.

A

c. is an endergonic reaction that takes place because it is coupled
to the exergonic hydrolysis of ATP.

42
Q

The fate of pyruvate produced during glycolysis depends
primarily on the availability of
a. NAD+ to keep the pathway going.
b. molecular oxygen.
c. ADP for conversion to ATP.
d. coenzyme A for further metabolism of pyruvate.
e. phosphoric acid for the synthesis of ATP.

A

b. molecular oxygen.

43
Q

Glycolysis
a. does not require O2 to generate energy.
b. requires O2 to generate energy.
c. is inhibited by O2.
d. rate is increased in the presence of O2.

A

a. does not require O2 to generate energy.

44
Q

The enzyme glucokinase
a. phosphorylates a number of different sugars, including glucose,
fructose, and mannose.
b. specifically phosphorylates glucose rather than other sugars.
c. is the only kinase involved in glycolysis.
d. none of the above.

A

b. specifically phosphorylates glucose rather than other sugars.

45
Q

The fate of NADH from glycolysis depends on whether conditions are anaerobic or aerobic.
a. True
b. False

A

a. True

46
Q

In humans, pyruvate can be converted to
a. acetyl-CoA only.
b. lactate only.
c. ethanol only.
d. acetyl-CoA and lactate.

A

d. acetyl-CoA and lactate.

47
Q

Which of the following is not true?
a. Corn is the only source of biofuels
b. Biofuels are related to glycolysis because fermentation is an
end process of anaerobic glycolysis
c. Corn, wood, animal dung, and many other products can produce
biofuels
d. Many carbohydrate sources can produce ethanol

A

a. Corn is the only source of biofuels

48
Q

The reactions where glucose is converted to glucose 6-phosphate
and fructose 6-phosphate is converted to fructose 1,5-bisphosphate
are examples of:
a. exergonic reactions
b. priming reactions
c. phosphorylation reactions
d. kinase reactions
e. all of these

A

e. all of these

49
Q

Which of the following terms describes an enzyme that catalyzes
electron transfer reactions?
a. dehydrogenase
b. isomerase
c. kinase
d. phosphatase

A

a. dehydrogenase

50
Q

What is the name of the pictured glycolytic intermediate?
a. 1-phosphoglycerate
b. glyceraldehyde-3-phosphate
c. dihydroxyacetone phosphate
d. 3-phosphoglycerate

A

d. 3-phosphoglycerate

51
Q

Alcohol dehydrogenase resembles lactate dehydrogenase in
that it
a. is nonallosteric.
b. is a dimer.
c. uses NAD+ as a coenzyme.
d. is not found in aerobic organisms.

A

c. uses NAD+ as a coenzyme.

52
Q

Anaerobic metabolism can occur in all these organisms or
cells, except:
a. Yeast
b. Red blood cells
c. Muscle tissue that is working very fast
d. Lactobacillus in milk
e. Anaerobic metabolism can occur in all of these.

A

e. Anaerobic metabolism can occur in all of these.

53
Q

The binding of glucose to hexokinase
a. is an example of lock-and-key binding of a substrate to the
active site of an enzyme.
b. is an example of induced-fit binding of a substrate to the active
site of an enzyme.
c. differs from the binding of substrates to other kinases.
d. is not well characterized.

A

b. is an example of induced-fit binding of a substrate to the active
site of an enzym

54
Q

In the conversion of glyceraldehyde 3-phosphate to 1,3-bisphosphoglycerate
a. an alcohol group is phosphorylated.
b. an alcohol is oxidized to an aldehyde.
c. an alcohol is oxidized to a carboxylic acid.
d. an aldehyde is oxidized to a carboxylic acid.

A

d. an aldehyde is oxidized to a carboxylic acid.

55
Q

In aerobic metabolism, what is the fate of pyruvate produced
by glycolysis?
a. Pyruvate loses carbon dioxide, and the remaining two carbon atoms become linked to coenzyme A.
b. Pyruvate loses carbon dioxide, producing acetaldehyde, which,
in turn, is reduced to ethanol.
c. Pyruvate is reduced to lactate.
d. None of these

A

a. Pyruvate loses carbon dioxide, and the remaining two carbon atoms become linked to coenzyme A.

56
Q

If glycolysis did not lead to the production of ATP, the overall
process would
a. release less energy
b. release more energy
c. absorb energy
d. not take place in aerobic organisms

A

b. release more energy

57
Q

The reduction of pyruvate to lactate
a. allows for recycling of NAD+.
b. is the process that aids in the recovery of sore muscles after
exercise.
c. is accompanied by phosphorylation of ADP.
d. does not occur in aerobic organisms.

A

a. allows for recycling of NAD+.

58
Q

Which of the following is not true?
a. Every reaction in a metabolic pathway must have a negative ”G, or the pathway cannot run.
b. the reaction with the largest negative ÄG is the hexokinase
reaction
c. the overall pathway of glycolysis has a negative ÄG
d. all of these are true

A

a. Every reaction in a metabolic pathway must have a negative ”G, or the pathway cannot run.

59
Q

Which of the following is not true?
a. Multiple isozymes of lactate dehydrogenase are used as clinical
means for diagnosing heart attacks.
b. Two enzymes involved in anaerobic glycolysis are found as
isozymes with 5 different forms
c. The M4 version of lactate dehydrogenase predominates in
heart tissue
d. After a myocardial infarction, the blood serum levels of MH3
and H4 isozymes increase

A

c. The M4 version of lactate dehydrogenase predominates in heart tissue

60
Q

Which of the following exercise(s) allosteric control in the
reaction of phosphofructokinase?
a. ATP
b. fructose 2,6-bisphosphate
c. both of these
d. neither of these

A

c. both of these

61
Q

What is the net ATP yield per glucose during glycolysis?
a. 1
b. 2
c. 3
d. 4
e. 6

A

b. 2

62
Q

In the conversion of glucose to pyruvate, how many of the
actual steps involve electron transfer?
a. none
b. 1
c. 2
d. 3
e. 4

A

b. 1

63
Q

Which enzyme catalyzes reaction the reaction shown?
a. enolase
b. pyruvate dehydrogenase
c. pyruvate kinase
d. phosphoglycerate mutase

A

c. pyruvate kinase

64
Q

Which of the following is true about phosphofructokinase?
a. It is a tetramer composed of different combinations of the M and L subunits
b. there are two isozymes, M4 and L4
c. there are a total of 6 isozyme types in the body
d. It is a dimer composed of M and L subunits
e. none of these

A

a. It is a tetramer composed of different combinations of the M and L subunits

65
Q

The ”G values for glycolytic reactions at physiological conditions
may be exergonic, even though the ”G°’ at “standard” conditions,
may be endergonic.
a. True
b. False

A

a. True

66
Q

How many different reactions involve substrate-level phosphorylation
during glycolysis?
a. 1
b. 2
c. 3
d. 4
e. 6

A

b. 2

67
Q

Which group of small molecules best fit the boxes associated with the reaction shown?
a b c
I. ATP ADP H2O
II. NADH NAD+ Pi
III. NAD+ NADH H2O
IV. NAD+ NADH Pi
a. I
b. II
c. III
d. IV

A

d. IV

Biochemistry (14 decks)

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