Deck 17: Glycolysis

Question 1

The DG values for glycolytic reactions at physiological conditions may be exergonic,even though the DG' at "standard" conditions,may be endergonic.

Answer 1

True

Question 2

In aerobic metabolism,what is the fate of pyruvate produced by glycolysis?
A)

A) Pyruvate loses carbon dioxide, and the remaining two carbon atoms become linked to coenzyme
B) Pyruvate loses carbon dioxide, producing acetaldehyde, which, in turn, is reduced to ethanol.
C) Pyruvate is reduced to lactate.
D) None of these

Answer 2

A

Question 3

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.

Answer 3

A

Question 4

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.

Question 5

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.

Question 6

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

Question 7

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.

Question 8

Which of the following enzymes interconverts an aldose and a ketose?

A) kinase
B) isomerase
C) mutase
D) dehydrogenase
E) phosphorylase

Question 9

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

Question 10

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.

Question 11

In humans,pyruvate can be converted to

A) acetyl-CoA only.
B) lactate only.
C) ethanol only.
D) acetyl-CoA and lactate.

Question 12

Which enzyme is the key regulatory enzyme in glycolysis?

A) Glyceraldehyde-3-phosphate dehydrogenase
B) Enolase
C) Phosphofructokinase
D) Aldolase

Question 13

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

Question 14

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

Question 15

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

Question 16

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.

Question 17

Which enzyme catalyzes the reaction shown?

A) an epimerase
B) an isomerase
C) a mutase
D) a dehydrogenase

Question 18

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.

Question 19

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

Question 20

What is the net ATP yield per glucose during glycolysis?

A) 1
B) 2
C) 3
D) 4
E) 6

Question 21

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.

Question 22

Which enzyme catalyzes reaction the reaction shown?

A) enolase
B) pyruvate dehydrogenase
C) pyruvate kinase
D) phosphoglycerate mutase

Question 23

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

Question 24

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.

Question 25

What kind of enzyme catalyzes the reaction shown?

A) an epimerase
B) an isomerase
C) a mutase
D) a dehydrogenase

Question 26

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.

Question 27

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

Question 28

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

Question 29

Which of the following terms describes an enzyme that catalyzes electron transfer reactions?

A) dehydrogenase
B) isomerase
C) kinase
D) phosphatase

Question 30

The step that commits the cell to metabolize glucose is catalyzed by

A) hexokinase.
B) phosphoglucomutase.
C) aldolase.
D) phosphofructokinase.

Question 31

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

Question 32

What is the name of the pictured glycolytic intermediate?

A) 1-phosphoglycerate
B) glyceraldehyde-3-phosphate
C) dihydroxyacetone phosphate
D) 3-phosphoglycerate

Question 33

Which of the following is not true?

A) Every reaction in a metabolic pathway must have a negative DG, 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

Question 34

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

Question 35

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.

Question 36

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

Question 37

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

Question 38

Which group of small molecules best fit the boxes associated with the reaction shown?

A) I
B) II
C) III
D) IV

Question 39

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.

Question 40

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.

Question 41

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.

Question 42

Which of the following enzymes catalyzes a dehydration reaction?

A) Glyceraldehyde-3-phosphate dehydrogenase
B) Enolase
C) Phosphofructokinase
D) Aldolase

Question 43

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.

Question 44

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

Question 45

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

Question 46

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.

Question 47

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.

Question 48

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.

Question 49

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.

Question 50

Which of the following enzymes of anaerobic metabolism is not tetrameric?

A) Hexokinase
B) Phosphofructokinase
C) Pyruvate kinase
D) Lactate Dehydrogenase

Question 51

Which of the following enzymes relies on thiamine pyrophosphate as a cofactor?

A) pyruvate decarboxylase
B) pyruvate kinase
C) lactate dehydrogenase
D) enolase

Question 52

The fate of NADH from glycolysis depends on whether conditions are anaerobic or aerobic.

Question 53

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.

Question 54

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

Question 55

An enzyme not involved in the control of glycolysis is

A) hexokinase.
B) triose phosphate isomerase.
C) pyruvate kinase.
D) phosphofructokinase.

Question 56

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

Question 57

How many different reactions involve substrate-level phosphorylation during glycolysis?

A) 1
B) 2
C) 3
D) 4
E) 6

Question 58

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%.

Question 59

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.

Question 60

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.

Question 61

Consider the following information: 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

Question 62

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

Question 63

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