MCC111 CHAPTER 17: GLYCOLYSIS Flashcards
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. does not require O2 to generate energy.
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.
B. molecular oxygen.
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. Pyruvate loses carbon dioxide, and the remaining two carbon atoms become linked to coenzyme A.
In humans, pyruvate can be converted to
A. acetyl-CoA only.
B. lactate only.
C. ethanol only.
D. acetyl-CoA and lactate.
D. acetyl-CoA and lactate.
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
D. fructose
What is the net ATP yield per glucose during glycolysis?
A. 1
B. 2
C. 3
D. 4
E. 6
B. 2
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
B. 1
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.
C. Fructose-6-phosphate, fructose-bisphosphate, 1,3-phosphoglyceric acid, 3-phosphoglyceric acid, PEP.
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. Corn is the only source of biofuels
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. kinase
The DG values for glycolytic reactions at physiological conditions may be exergonic, even though the DG’ at “standard” conditions, may be endergonic.
A. True
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
E. all of these
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.
C. is an endergonic reaction that takes place because it is coupled to the exergonic hydrolysis of ATP.
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.
B. specifically phosphorylates glucose rather than other sugars.
Which enzyme catalyzes the reaction shown?
A. an epimerase
B. an isomerase
C. a mutase
D. a dehydrogenase
B. an isomerase
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.
B. is an example of induced-fit binding of a substrate to the active site of an enzyme.
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.
C. fructose 1,6-bisphosphate can undergo no other reactions than those of glycolysis.
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
D. all of these
Which of the following enzymes interconverts an aldose and a ketose?
A. kinase
B. isomerase
C. mutase
D. dehydrogenase
E. phosphorylase
B. isomerase
Which enzyme is the key regulatory enzyme in glycolysis?
A. Glyceraldehyde-3-phosphate dehydrogenase
B. Enolase
C. Phosphofructokinase
D. Aldolase
C. Phosphofructokinase
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
C. both of these
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 reverse aldol condensation.
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
B. glyceraldehyde-3-phosphate is being continuously drained off for the subsequent reaction in the glycolytic pathway
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. is catalyzed by the enzyme triose phosphate isomerase.
The step that commits the cell to metabolize glucose is catalyzed by
A. hexokinase.
B. phosphoglucomutase.
C. aldolase.
D. phosphofructokinase.
D. phosphofructokinase.
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
B. having the product of the reaction continuously consumed.
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. Aldolase
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
A. Every reaction in a metabolic pathway must have a negative DG, or the pathway cannot run.
Which of the following terms describes an enzyme that catalyzes electron transfer reactions?
A. dehydrogenase
B. isomerase
C. kinase
D. phosphatase
A. dehydrogenase
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
C. glyceraldehyde-3-phosphate dehydrogenase
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. substrate-level phosphorylation.
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
D. IV
a b c
IV. NAD+ NADH Pi