Question 1

What is the initial step in the mechanism of fructose-1,6-bisphosphate aldolase when the substrate is fructose-1,6-bisphosphate in its open-chain form?

Accepted Answer

A)  attack of C-2 carbonyl group by the amine of lysine
B)  deprotonation of C-3 hydroxyl by aspartate
C)  protonation of C-2 carbonyl oxygen by histidine
D)  attack of C-2 carbonyl group by the thiol of cysteine
E)  none of the above

Question 2

Which of the following glycolytic reactions is freely reversible?

Accepted Answer

A)  hexokinase
B)  phosphofructokinase
C)  triose phosphate isomerase
D)  pyruvate kinase
E)  none of the above

Question 3

If unregulated, which of the following pairs of enzymes would represent a futile cycle?

Accepted Answer

A)  pyruvate kinase and pyruvate carboxylase
B)  pyruvate carboxylase and phosphoenolpyruvate carboxykinase
C)  pyruvate kinase and fructose-1,6-bisphosphatase
D)  fructose-1,6-bisphosphatase and phosphofructokinase
E)  glucose-6-phosphatase and phosphofructokinase

Question 4

Conversion of pyruvate to acetaldehyde requires _______ while conversion of acetaldehyde to ethanol requires _______.

Accepted Answer

A)  thiamine pyrophosphate; NAD+
B)  pyridoxal phosphate; FADH2
C)  biotin; NADH
D)  biotin; FAD
E)  thiamine pyrophosphate; NADH

Question 5

Which of the following pairs of phosphorylated molecules contains an intermediate of glycolysis with high phosphate transfer potential and one with low phosphate transfer potential?

Accepted Answer

A)  fructose-1,6-bisphosphate and fructose-6-phosphate
B)  phosphoenolpyruvate and glyceraldehyde-3-phosphate
C)  fructose-1,6-bisphosphate and 3-phosphoglycerate
D)  1,3-bisphosphoglycerate and phosphoenolpyruvate
E)  1,3-bisphosphoglycerate and pyruvate

Question 6

For the interconversion of an aldose and ketose, show the intermediate of the reaction.

Accepted Answer

The answer of For the interconversion of an aldose and...

Question 7

Fill in the missing two intermediates of glycolysis:

Accepted Answer

The answer of Fill in the missing two intermediates of...

Question 8

In the mammalian liver, hexokinase IV is sequestered in _______ when glucose concentrations are low. When glucose concentrations are high, it is found in the cytosol bound to the enzyme ________.

Accepted Answer

A)  nucleus; PFK-2
B)  Golgi apparatus; PFK-2
C)  endoplasmic reticulum; PFK-2
D)  nucleus; PFK-1
E)  Golgi apparatus; PFK-1

Question 9

The conversion of 3-phosphoglycerate to phosphoenolpyruvate requires two reactions. Which of the following correctly identifies the types of reactions in the proper order of glycolysis?

Accepted Answer

A)  isomerization, hydration
B)  hydration, isomerization
C)  dehydration, isomerization
D)  isomerization, dehydration
E)  mutation, dehydration

Question 10

When glucagon binds to receptors on mammalian liver cells, which of the following occurs due to enzyme phosphorylation?

Accepted Answer

A)  activation of PFK-2 followed by activation of glycolysis
B)  activation of FBPase-2 followed by inhibition of gluconeogenesis
C)  activation of PFK-2 followed by activation of gluconeogenesis
D)  activation of FBPase-2 followed by activation of gluconeogenesis
E)  activation of PFK-2 followed by inhibition of glycolysis

Question 11

Which isoform of hexokinase is found in the vertebrate liver?

Accepted Answer

A)  hexokinase I
B)  hexokinase II
C)  hexokinase III
D)  hexokinase IV
E)  all of the above

Question 12

In its non-phosphorylated state, glycogen phosphorylase can be activated by which of the following molecules?

Accepted Answer

A)  ATP
B)  glucose-6-phosphate
C)  glucose
D)  AMP
E)  none of the above

Question 13

During the energy investment phase of glycolysis, _____ reaction(s) use ATP as a substrate while during the energy generation phase, _____ reactions produce ATP as a product.

Accepted Answer

A)  2; 2
B)  2; 4
C)  1; 2
D)  1; 4
E)  0; 2

Question 14

Which of the following enzymes is activated when acted on by phosphoprotein phosphatase 1?

Accepted Answer

A)  glycogen synthase
B)  glycogen phosphorylase
C)  phosphorylase kinase
D)  phosphoprotein phosphatase inhibitor 1
E)  protein kinase A A

Question 15

The conversion of ribulose-5-phosphate to xylulose-5-phosphate requires what enzyme?

Accepted Answer

A)  phosphopentose isomerase
B)  phosphopentose epimerase
C)  transketolase
D)  transaldolase
E)  lactonase

Question 16

A transketolase enzyme transfers a _____ carbon fragment from a(n) ________ to a(n) ________.

Accepted Answer

A)  2; aldose; ketose
B)  2; ketose; aldose
C)  2; ketose; ketose
D)  3; aldose; ketose
E)  3; ketose; aldose

Question 17

Experiments that investigated the Pasteur effect showed that when oxygen is introduced to cells where glycolysis is occurring, all intermediates beginning with ________ become depleted due to inhibition of the enzyme _________.

Accepted Answer

A)  fructose-1,6-bisphosphate; phosphofructokinase
B)  glucose-6-phosphate: hexokinase
C)  fructose-6-phosphate; phosphofructokinase
D)  fructose-1,6-bisphosphate; fructose-1,6-bisphosphate aldolase
E)  phosphoenolpyruvate; pyruvate kinase

Question 18

Which of the following is correctly paired with the glycolytic intermediate that serves as its precursor?

Accepted Answer

A)  ribulose-5-phosphate: fructose-6-phosphate
B)  serine: phosphoenolpyruvate
C)  glycogen: glucose-6-phosphate
D)  glycerol-3-phosphate: glyceraldehyde-3-phosphate
E)  glucosamine: fructose-1,6-bisphosphate

Question 19

With respect to carbons 1 and 2 of the intermediate in the conversion of glucose-6-phosphate to fructose-6-phosphate, which of the following would best describe this intermediate?

Accepted Answer

A)  vicinal diol
B)  enediol
C)  aldehyde
D)  ketone
E)  enol

Question 20

Under conditions of strenuous exercise, gluconeogenesis occurs primarily in the _______ using _______ formed in the skeletal muscle

Accepted Answer

A)  kidney; alanine
B)  muscle; glycerol
C)  liver; propionate
D)  kidney; acetyl-CoA
E)  liver; lactate E

Exam 13: Carbohydrate Metabolism: Glycolysis, Gluconeogenesis, Glycogen Metabolism, and the Pentose Phosphate Pathway

What is the initial step in the mechanism of fructose-1,6-bisphosphate aldolase when the substrate is fructose-1,6-bisphosphate in its open-chain form?

Correct AnswerverifiedShow Answer

Which of the following glycolytic reactions is freely reversible?

Correct AnswerverifiedShow Answer

If unregulated, which of the following pairs of enzymes would represent a futile cycle?

Correct AnswerverifiedShow Answer

Conversion of pyruvate to acetaldehyde requires _______ while conversion of acetaldehyde to ethanol requires _______.

Correct AnswerverifiedShow Answer

Which of the following pairs of phosphorylated molecules contains an intermediate of glycolysis with high phosphate transfer potential and one with low phosphate transfer potential?

Correct AnswerverifiedShow Answer

For the interconversion of an aldose and ketose, show the intermediate of the reaction.

Correct AnswerverifiedShow Answer

Fill in the missing two intermediates of glycolysis:

Correct Answerverified11ea7cd4_c4b1_82c4_a2ab_9b802765ee08_TB2679_00

In the mammalian liver, hexokinase IV is sequestered in _______ when glucose concentrations are low. When glucose concentrations are high, it is found in the cytosol bound to the enzyme ________.

Correct AnswerverifiedShow Answer

The conversion of 3-phosphoglycerate to phosphoenolpyruvate requires two reactions. Which of the following correctly identifies the types of reactions in the proper order of glycolysis?

Correct AnswerverifiedShow Answer

When glucagon binds to receptors on mammalian liver cells, which of the following occurs due to enzyme phosphorylation?

Correct AnswerverifiedShow Answer

Which isoform of hexokinase is found in the vertebrate liver?

Correct AnswerverifiedShow Answer

In its non-phosphorylated state, glycogen phosphorylase can be activated by which of the following molecules?

Correct AnswerverifiedShow Answer

During the energy investment phase of glycolysis, _____ reaction(s) use ATP as a substrate while during the energy generation phase, _____ reactions produce ATP as a product.

Correct AnswerverifiedShow Answer

Which of the following enzymes is activated when acted on by phosphoprotein phosphatase 1?

Correct AnswerverifiedA

The conversion of ribulose-5-phosphate to xylulose-5-phosphate requires what enzyme?

Correct AnswerverifiedShow Answer

A transketolase enzyme transfers a _____ carbon fragment from a(n) ________ to a(n) ________.

Correct AnswerverifiedShow Answer

Experiments that investigated the Pasteur effect showed that when oxygen is introduced to cells where glycolysis is occurring, all intermediates beginning with ________ become depleted due to inhibition of the enzyme _________.

Correct AnswerverifiedShow Answer

Which of the following is correctly paired with the glycolytic intermediate that serves as its precursor?

Correct AnswerverifiedShow Answer

With respect to carbons 1 and 2 of the intermediate in the conversion of glucose-6-phosphate to fructose-6-phosphate, which of the following would best describe this intermediate?

Correct AnswerverifiedShow Answer

Under conditions of strenuous exercise, gluconeogenesis occurs primarily in the _______ using _______ formed in the skeletal muscle

Correct AnswerverifiedE

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Conversion of pyruvate to acetaldehyde requires _ while conversion of acetaldehyde to ethanol requires _.

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In the mammalian liver, hexokinase IV is sequestered in _ when glucose concentrations are low. When glucose concentrations are high, it is found in the cytosol bound to the enzyme __.

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During the energy investment phase of glycolysis, _ reaction(s) use ATP as a substrate while during the energy generation phase, _ reactions produce ATP as a product.

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A

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A transketolase enzyme transfers a _ carbon fragment from a(n) to a(n) ____.

Correct Answer
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Experiments that investigated the Pasteur effect showed that when oxygen is introduced to cells where glycolysis is occurring, all intermediates beginning with become depleted due to inhibition of the enzyme _.

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Under conditions of strenuous exercise, gluconeogenesis occurs primarily in the _ using _ formed in the skeletal muscle

Correct Answer
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