Chapter 18—Glycolysis
MULTIPLE CHOICE
1. All are characteristic of the conversion of glucose to lactate EXCEPT:
a.
anaerobic pathway with no net oxidation.
b.
“primed” by ATP phosphorylation.
c.
located in the cytosol.
d.
approximately 50% efficient in erythrocytes.
e.
net production of four ATP per glucose.
2. -D-Glucose + ATP → ____ + ____ + H+
a.
-D-fructose; ADP
b.
-D-glucose-1-phosphate; AMP
c.
-D-glucose-1-phosphate; ADP
d.
-D-glucose-6-phosphate; ADP
e.
D-glucose-1,6-bisphosphate; AMP
3. For the first five steps of glycolysis, the appropriate sequence of enzymes is:
A.
phosphofructokinase-1 (PFK-1).
B.
hexokinase / glucokinase.
C.
fructose bisphosphate aldolase.
D.
Phosphoglucoisomerase.
E.
triose phosphate isomerase (TPI).
a.
A, C, B, E, D
b.
B, C, D, E, A
c.
B, D, C, A, E
d.
D, B, A, C, E
e.
B, D, E, C, A
4. All are important reasons to phosphorylate glucose in the first step of glycolysis EXCEPT:
a.
the large positive free energy is important in getting the pathway started.
b.
glucose-6-phosphate has a negative charge preventing transport out of the cell.
c.
the concentration of free glucose in the cell is lowered favoring influx of glucose.
d.
phosphorylation keeps the glucose in the cell.
e.
regulatory control can be imposed only at a reaction not at equilibrium.
5. Hexokinase and glucokinase belong to the kinase subclass of what class of enzymes?
a.
oxidoreductase
b.
isomerase
c.
transferase
d.
hydrolase
e.
lyase
6. Glucokinase has a Km value of 10.0 mM, whereas hexokinase has a Km value of 0.1 mM. This is
consistent with which of the following?
a.
glucokinase acts on glucose at low concentrations.
b.
glucokinase acts on glucose only at high glucose concentrations.
c.
glucokinase phosphorylates most of the glucose at low glucose levels.
d.
hexokinase acts on glucose only at high levels of glucose.
e.
hexokinase acts at about half-maximal velocity at glucose concentrations of 4-5 mM.
7. All are characteristics of Type 1 diabetes mellitus EXCEPT:
a.
low levels of glucokinase.
b.
glucokinase is induced.
c.
insufficient insulin is produced.
d.
production of little liver glycogen.
e.
all are true.
8. All are true for the isomerase reaction of glucose-6-phosphate to fructose-6-phosphate EXCEPT:
a.
Mg2+ is required for activity.
b.
it is an aldose to ketose isomerization.
c.
“moving” the carbonyl from C-1 to C-2 creates a new primary alcohol group at C-1.
d.
the reaction is irreversible with a large negative G.
e.
the enzyme belongs to the isomerase class of enzymes.
9. Which of the following pathways is NOT properly paired with its precursor?
a.
glycogen synthesis: glucose-1-phosphate
b.
pentose phosphate pathway: glucose-6-phosphate
c.
glucosamine-6-phosphate: glucose-6-phosphate
d.
glucuronic acid: glucose-6-phosphate
e.
all are correctly paired
10. The step that commits glucose to glycolysis is catalyzed by:
a.
hexokinase.
b.
pyruvate kinase
c.
phosphofructokinase-1 (PFK-1).
d.
glucokinase.
e.
phosphofructokinase-2 (PFK-2)
11. All are characteristics of the phosphofructokinase-1 catalyzed reaction EXCEPT:
a.
exergonic.
b.
“priming reaction“.
c.
“valve” controlling the rate of glycolysis.
d.
commits the cell to metabolize glucose.
e.
all are true.
12. For phosphofructokinase-1:
a.
Low ATP stimulates the enzyme, but fructose-2,6-bisphosphate inhibits
b.
High ATP stimulates the enzyme, and fructose-2,6-bisphosphate activates
c.
High ATP stimulates the enzyme, but fructose-2,6-bisphosphate inhibits
d.
Low ATP stimulates the enzyme, and fructose-2,6-bisphosphate activates
e.
ATP and fructose-2,6-bisphosphate both inhibit the enzyme
13. When phosphoglucoisomerase is secreted by T-cells it:
a.
phosphorylates galactose.
b.
isomerizes galactose-6-phosphate to glucose-6-phosphate.
c.
promotes the survival of certain spinal neurons and sensory nerves.
d.
glycosylates sphingolipids surrounding nerves.
e.
none of the above.
14. All of the following characterize phosphofructokinase-1 (PFK-1) EXCEPT:
a.
the most important regulatory site in glycolysis.
b.
ATP increases the affinity of the enzyme for fructose-6-phosphate.
c.
PFK-1 activity is a function of the energy charge of the cell.
d.
AMP decreases the Km of PFK-1 for fructose-6-phosphate.
e.
the subunits of PFK-1 behave cooperatively.
15. All are allosteric regulators of phosphofructokinase-1 EXCEPT:
a.
glucose-6-phosphate by inhibition.
b.
ATP by inhibition.
c.
AMP by stimulation.
d.
citrate by inhibition.
e.
-D-fructose-2,6-bisphosphate by stimulation.
16. Adenylate kinase catalyzes the reaction:
ADP + ____ ____ + AMP
a.
AMP; Pi
b.
ADP; ADP
c.
ADP; ATP
d.
ATP; ADP
e.
AMP; ATP
Garrett/Grisham 5e Test Bank 4
17. All of the following are characteristic of the coupling between glycolysis and the citric acid cycle
EXCEPT:
a.
glycolysis feeds acetyl CoA, via pyruvate, to the citric acid cycle.
b.
citrate inhibits glucokinase to regulate glycolysis.
c.
citrate builds up when citric acid cycle reaches saturation.
d.
citric acid cycle directs electrons into electron transport chain for the purpose of ATP
production.
e.
ATP production via citric acid cycle, electron transport, and oxidative phosphorylation
inhibits glycolysis.
18. All are characteristic of fructose bisphosphate aldolase in animal tissues EXCEPT:
a.
It belongs to the lyase class of enzymes.
b.
The reaction is reversible in erythrocytes (G is very small).
c.
It is a Class II aldolase.
d.
The mechanism involves formation of a Schiff base with an active-site lysine side-chain.
e.
The products are an aldotriose phosphate and a ketotriose phosphate.
19. Class I aldolases are characterized by:
a.
an endiol intermediate.
b.
a requirement for biotin.
c.
a Schiff base intermediate.
d.
inhibition by EDTA due to a metal ion requirement.
e.
coenzyme requirement for thiamin pyrophosphate (TPP).
20. Dihydroxyacetone phosphate is:
a.
an aldotriose.
b.
an enantiomer of glyceraldehyde-3-phosphate.
c.
derived from C4-C6 of fructose-1,6-bisphosphate.
d.
isomerized to glyceraldehyde-3-phosphate by triose phosphate isomerase (TPI).
e.
the least abundant component of the TPI reaction at equilibrium.
21. The mechanism of triose phosphate isomerase is very similar in function to:
a.
hexokinase.
b.
phosphoglucoisomerase.
c.
phosphofructokinase.
d.
fructose-1,6-bisphosphate aldolase.
e.
none of the above.
22. In the second half of the glycolytic pathway, ____ ATP molecules are produced and with the offset of
____ ATPs consumed in the first half, the net yield is ____ ATPs per glucose.
a.
four; four; zero
b.
four; two; two
c.
two; two; four
d.
two; one; one
e.
four; one; three
Garrett/Grisham 5e Test Bank 5
23. The first intermediate of glycolysis with free energy of hydrolysis more negative than that of ATP is:
a.
glucose-6-phosphate.
b.
fructose-6-phosphate.
c.
fructose-1,6-bisphosphate.
d.
dihydroxyacetone phosphate.
e.
1,3-bisphosphoglycerate.
24. Glyceraldehyde-3-phosphate dehydrogenase belongs to what class of enzymes?
a.
oxidoreductases
b.
isomerases
c.
transferases
d.
hydrolases
e.
ligases
25. The reaction mechanism for glyceraldehyde-3-phosphate dehydrogenase involves ____ attack by a
cysteine -SH group on the ____ carbon of the substrate to form a hemithioacetal.
a.
electrophilic; carbonyl
b.
electrophilic; acidic
c.
nucleophilic; amino
d.
nucleophilic; carbonyl
e.
SN2 ; amino
26. Substrate-level phosphorylation occurs in glycolysis in the reaction catalyzed by ____ and belongs to
____ class of enzymes.
a.
phosphoglycerate kinase; transferase
b.
hexokinase; transferase
c.
phosphofructokinase; transferase
d.
glucokinase; transferase
e.
glyceraldehyde-3-phosphate dehydrogenase; oxidoreductase
27. The reaction, 1,3-bisphosphoglycerate → 2,3-bisphosphoglycerate, is catalyzed by:
a.
bisphosphoglycerate phosphatase.
b.
bisphosphoglycerate mutase.
c.
2,3-bisphosphoglycerate synthetases.
d.
3-phosphoglycerate isomerase.
e.
1,3-bisphosphoglycerate hydrolase.
28. A mutase catalyzes which of the reactions, and belongs to which class of enzymes?
a.
2-phosphoglycerate phosphoenolpyruvate + H2O; lyase
b.
pyruvate + NADH + H+ lactate + NAD+; oxidoreductase
c.
3-phosphoglycerate 2-phosphoglycerate; isomerase
d.
dihydroxyacetone phosphate glyceraldehyde-3-phosphate; isomerase
e.
glucose-6-phosphate fructose-6-phosphate; isomerase
29. All are true for 2,3-bisphosphoglycerate (2,3-BPG) EXCEPT:
a.
erythrocytes typically have high levels of 2,3-BPG.
b.
2,3-BPG is synthesized from 1,3-BPG.
c.
a kinase converts 2,3-BPG to 3-phosphoglycerate.
d.
2,3-BPG is involved in unloading oxygen from hemoglobin.
e.
bisphosphoglycerate mutase is an isomerase.
30. Which of the following amino acids provides the nucleophile in the reaction of class I aldolase?
a.
Lys
b.
Cys
c.
Ser
d.
Glu
e.
His
31. Which of the following has the most highly exergonic hydrolysis (considering that only the highest
energy bond is hydrolyzed)?
a.
phosphoenolpyruvate
b.
fructose-6-phosphate
c.
1,3-bisphoshpoglycerate
d.
2,3-bisphoshpoglycerate
e.
fructose-1,6-bisphosphate
32. Addition of water across a double bond, or removal of water to form a double bond, is catalyzed by a
subclass of the lyase class of enzymes. Which of these enzymes would be a lyase?
a.
glyceraldehyde-3-phosphate dehydrogenase
b.
triose phosphate isomerase (TPI)
c.
phosphoglycerate mutase
d.
hexokinase
e.
enolase
33. PEP and 2-PG have similar amounts of potential metabolic energy with respect to decomposition to Pi,
CO2 and H2O, but the enolase reaction:
a.
creates a much more unstable reactive intermediate.
b.
rearranges 2-PG into a form from which more potential energy can be released by
hydrolysis.
c.
rearranges 2-PG to a form with greater binding potential to the enzyme.
d.
changes the G of the reaction to increase the potential energy.
e.
none are true.
34. The high free energy change for the conversion of PEP to pyruvate is due largely to the ____
conversion of the relatively unstable ____ tautomer of pyruvate to the more stable ____ form
following the phosphoryl group transfer step.
a.
unfavorable; enol; keto
b.
unfavorable; keto; aldol
c.
favorable; keto; enol
d.
favorable; enol; keto
e.
favorable; enol; aldol
35. All are allosteric effectors of pyruvate kinase EXCEPT:
a.
pyruvate.
b.
AMP.
c.
ATP.
d.
acetyl-CoA.
e.
fructose-1,6-bisphosphate.
36. All of the following enzymes of glycolysis are allosterically regulated EXCEPT:
a.
phosphofructokinase-1.
b.
glyceraldehyde-3-phosphate dehydrogenase.
c.
hexokinase.
d.
pyruvate kinase.
e.
none of the above.
37. Which of the following enzymes catalyzes a reversible reaction that is an equilibrium controlled step
of glycolysis?
a.
phosphofructokinase-1
b.
aldolase
c.
pyruvate kinase
d.
glucokinase
e.
none of the above
38. Hormones such as glucagon ____ glycolysis by activating cAMP-dependent protein kinase that will
____ pyruvate kinase to ____ the enzyme.
a.
activate; carboxylate; activate
b.
activate; phosphorylate; activate
c.
activate; phosphorylate; inhibit
d.
inhibit; phosphorylate; inhibit
e.
inhibit; phosphorylate; activate
39. NADH, ____ and ____ are products of glycolysis, and the NADH must be recycled to ____ before it
becomes limiting in glycolysis.
a.
ATP; pyruvate; NAD+
b.
NAD+; ATP; pyruvate
c.
ATP; NAD+; ATP
d.
ATP; pyruvate; lactate
e.
None are true
40. The most common form of hemolytic anemia can be the result of a genetic defect in:
a.
hexokinase.
b.
PFK-1.
c.
pyruvate kinase
d.
phosphoglycerate mutase.
e.
TPI.
41. The oxidation of one mole of glucose by anaerobic glycolysis yields a net of:
a.
two moles of lactate and two moles of ATP.
b.
two moles of lactate, two moles of NADH, and two moles of ATP.
c.
two moles of lactate and six moles of ATP.
d.
two moles of pyruvate and two moles of ATP.
e.
two moles of pyruvate, two moles of NADH, and four moles of ATP.
42. In alcohol fermentation from glucose, the two oxidation-reduction reactions are catalyzed by:
a.
glyceraldehyde-3-phosphate dehydrogenase and alcohol dehydrogenase
b.
glyceraldehyde-3-phosphate dehydrogenase and pyruvate decarboxylase
c.
alcohol dehydrogenase and pyruvate decarboxylase
d.
lactate dehydrogenase and pyruvate decarboxylase
e.
glyceraldehyde-3-phosphate dehydrogenase and lactate dehydrogenase
43. Under anaerobic conditions, skeletal muscle generates lactate from pyruvate to:
a.
lower the pH.
b.
promote release of oxygen from hemoglobin.
c.
generate additional ATP.
d.
be warning of muscle fatigue.
e.
regenerate NAD+ for further glycolysis.
44. Lactate produced by anaerobic muscle tissue is:
a.
stored in muscle until oxygen is available.
b.
carried by the blood to the liver for gluconeogenesis and converted to glucose.
c.
further reduced to glycerol in muscle.
d.
transferred to erythrocytes to release oxygen from hemoglobin.
e.
none of the above.
45. Seven of the ten reactions of glycolysis are reversible (G near zero) and can be used in reverse of
glycolysis for gluconeogenesis. The three irreversible reactions are catalyzed by:
a.
hexokinase, phosphoglycerate kinase, pyruvate kinase.
b.
triose phosphate isomerase, phosphoglycerate mutase, pyruvate kinase.
c.
enolase, phosphoglycerate kinase, phosphofructokinase-1.
d.
hexokinase, phosphoglucoisomerase, glyceraldehyde-3-phosphate dehydrogenase.
e.
hexokinase, phosphofructokinase-1, pyruvate kinase.
46. In the liver, ____ is used to phosphorylate fructose to ____.
a.
phosphofructokinase-1; fructose-6-phosphate
b.
phosphofructokinase-1; fructose-1-phosphate
c.
fructokinase; fructose-6-phosphate
d.
fructokinase; fructose-1-phosphate
e.
hexokinase; fructose-1-phosphate
47. Which of the following enzymes is NOT used when fructose is metabolized to pyruvate in the liver?
a.
triose phosphate isomerase
b.
glyceraldehyde-3-phospate dehydrogenase
c.
glucokinase
d.
phosphofructokinase-1
e.
pyruvate kinase
48. Fructose in the diet or fructose from sucrose in the diet can be a source of calories for fat synthesis in
the liver because:
a.
ketoses are fattening
b.
fructose enters glycolysis after the primary regulation point, PFK-1
c.
fructose provides a net of four ATP from glycolysis
d.
fructose enters the branch of glycolysis that forms fat
e.
glycerol (the “backbone” of triacylglycerols) comes specifically from fructose
49. Which of the following statements is correct regarding sugar metabolism?
a.
lactase, a -galactosidase type enzyme, cleaves the (1,4) glycosidic bond observed in
lactose
b.
in the liver, fructose is converted to fructose-1-P, then to dihydroxyacetone and
glyceraldehyde-3-phosphate, thus skipping normal glycolytic regulation
c.
in the muscle, fructose is converted into fructose-1-P by hexokinase
d.
galactose enters glycolysis as galactose-6-P since the stereochemistry at C-4 is not critical
for the first few enzymes of glycolysis
e.
None of the above are correct
50. The rare hereditary galactosemia involves defects in:
a.
galactokinase.
b.
galactose-1-phosphate uridylyltransferase.
c.
phosphoglucomutase.
d.
UDP-glucose-4-epimerase.
e.
UDP-glucose pyrophosphorylase.
51. UDP–galactose is converted to UDP-glucose by the enzyme:
a.
galactokinase.
b.
galactose-uridylyltransferase.
c.
Phosphoglucomutase.
d.
UDP-glucose-4-epimerase.
e.
UDP-galactose-2-epimerase.
52. Lactose synthase is a dimeric complex of:
a.
lactose and -galactosidase.
b.
galactosyl transferase and lactase.
c.
-lactalbumin and galactosyl transferase.
d.
galactosyl transferase and -galactosidase.
e.
-lactalbumin and -galactosidase.
53. Galactosemic individuals can be treated by ____ and the abnormality may disappear in adults due to
metabolism of galactose-1-phosphate by:
a.
medication; UDP-glucose pyrophosphorylase.
b.
medication; UDP-glucose-4-epimerase.
c.
restrictive diet; phosphoglucomutase.
d.
restrictive diet; UDP-glucose pyrophosphorylase.
e.
all of the above.
54. Glycerol from hydrolysis of triacylglycerols enters glycolysis at:
a.
glyceraldehyde-3-phosphate.
b.
3-phosphoglycerate.
c.
2-phosphoglycerate.
d.
dihydroxyacetone phosphate.
e.
1,3-bisphosphoglycerate.
55. Lactose intolerance is a deficiency of the enzyme ____ that results in the metabolism of lactose by
____.
a.
lactose synthase; intestinal enzymes
b.
lactase; intestinal bacteria
c.
lactase; intestinal viruses
d.
-galactosidase; -amylase
e.
none of the above
56. If glucose was labeled with 14C at carbon #6, what carbon of pyruvate would have the 14C?
a.
carboxyl carbon
b.
ketone carbon
c.
methyl carbon
d.
the 14C would be lost as CO2
e.
the 14C could be present at any of the carbons of pyruvate
57. If yeast cells were given glucose that was labeled with 14C at carbon 3, where would the 14C by found
after glycolysis under anaerobic conditions?
a.
CO2
b.
Ethanol, C1
c.
Ethanol, C2
d.
Lactic acid, C1
e.
Lactic acid, C3
58. AMP is often used in the cytosol as an indicator of low cellular energy. Which of the following
enzymes would be activated by AMP?
a.
hexokinase
b.
phosphoglycerate kinase
c.
phosphofructokinase-1
d.
glyceraldehyde-3-phosphate dehydrogenase
e.
both A and C are correct
59. Which of the following enzymes is correctly paired with an activator?
a.
hexokinase: ATP
b.
phosphofructokinase-1: fructose-2,6-bisphosphate
c.
pyruvate kinase: ADP
d.
glyceraldehyde-3-phosphate dehydrogenase: NAD+
e.
glucokinase: glucose
60. Which of the following enzymes is correctly paired with an inhibitor?
a.
hexokinase: ATP
b.
phosphofructokinase-1: AMP
c.
pyruvate kinase: ATP
d.
phosphofructokinase-2: citrate
e.
glyceraldehyde-3-phosphate dehydrogenase: 1,3-bisphosphoglycerate
61. Which of the following enzymes is inhibited by phosphorylation?
a.
hexokinase
b.
glucokinase
c.
phosphofructokinase-1
d.
phosphoglycerate kinase
e.
pyruvate kinase
62. Which of the following enzymes has two different binding sites for ATP, one a regulatory site and the
other a substrate site?
a.
hexokinase
b.
glucokinase
c.
phosphofructokinase-1
d.
phosphoglycerate kinase
e.
pyruvate kinase