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
What kind of enzyme catalyzes the reaction shown?
A. an epimerase
B. an isomerase
C. a mutase
D. a dehydrogenase
D. a dehydrogenase
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.
B. the dehydration of 2-phosphoglycerate.
The nicotinamide-binding region in glyceraldehyde-3-phosphate dehydrogenase is similar to all other NAD binding domains.
A. True
During glycolysis, ATP is synthesized from ADP and a phosphate group transferred from an acid anhydride.
A. True
What is the name of the pictured glycolytic intermediate?
A. 1-phosphoglycerate
B. glyceraldehyde-3-phosphate
C. dihydroxyacetone phosphate
D. 3-phosphoglycerate
D. 3-phosphoglycerate
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.
C. The standard free energy of the hydrolysis reaction is more negative than that for hydrolysis of the new phosphate compound being formed.
Which enzyme catalyzes reaction the reaction shown?
A. enolase
B. pyruvate dehydrogenase
C. pyruvate kinase
D. phosphoglycerate mutase
C. pyruvate kinase
The amino acid cysteine is important in adding a second phosphate to glyceraldehyde phosphate in the glyceraldehyde-3-phosphate dehydrogenase reaction.
A. True
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.
C. Aldolase
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.
D. phosphoglycerate kinase.
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.
C. 3
Which of the following enzymes catalyzes a dehydration reaction?
A. Glyceraldehyde-3-phosphate dehydrogenase
B. Enolase
C. Phosphofructokinase
D. Aldolase
B. Enolase
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.
D. an aldehyde is oxidized to a carboxylic acid.
An enzyme not involved in the control of glycolysis is
A. hexokinase.
B. triose phosphate isomerase.
C. pyruvate kinase.
D. phosphofructokinase.
B. triose phosphate isomerase.
How many different reactions involve substrate-level phosphorylation during glycolysis?
A. 1
B. 2
C. 3
D. 4
E. 6
B. 2
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. allows for recycling of NAD+.
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.
E. Anaerobic metabolism can occur in all of these.
Which of the following enzymes of anaerobic metabolism is not tetrameric?
A. Hexokinase
B. Phosphofructokinase
C. Pyruvate kinase
D. Lactate Dehydrogenase
A. Hexokinase
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
C. The M4 version of lactate dehydrogenase predominates in heart tissue
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
D. both CO2 and ethanol.
Which of the following enzymes relies on thiamine pyrophosphate as a cofactor?
A. pyruvate decarboxylase
B. pyruvate kinase
C. lactate dehydrogenase
D. enolase
A. pyruvate decarboxylase
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
D. can be detected by measuring the level of acetaldehyde in the bloodstream of a pregnant woman
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.
C. lactic acid.
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.
C. uses NAD+ as a coenzyme.
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.
C. involved in transfers of two-carbon groups.
The fate of NADH from glycolysis depends on whether conditions are anaerobic or aerobic.
A. True
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
D. a dehydrogenase
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%.
B. 30%.
Consider the following information:
phosphoenolpyruvate ® pyruvate DG’ = -61.9 kJ/mol
ADP + Pi ® ATP DG’ = +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
B. 2
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
B. release more energy
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
B. conversion to acetaldehyde
How many ATP are produced in Glycolysis?
2
What is the function of Kinase?
Transfer Phosphate group from ATP
What is the function of Isomerase?
Converts isomers to another isomer
What is the function of Aldolase?
Cleaves
What is the function of Dehydrogenase?
Removes H+ by oxidation. (Usually NAD+)
What is the function of Mutases?
An enzyme of the isomerase class that catalyzes the shifting of a functional group from one position to another within the same molecule. (Moves phosphate group)
What is the unique property of Hexokinase?
An enzyme that phosphorylates hexoses (six-carbon sugars), forming hexose phosphate (substrate is not necessarily glucose; rather it can be any number of hexoses).
Hexokinase can transfer an inorganic phosphate group from ATP to a substrate.
What is the relationship between Hexokinase, Glucokinase, and blood sugar?
Hexokinases should not be confused with glucokinase, which is a specific isoform of hexokinase. While other hexokinases are capable of phosphorylating several hexoses, glucokinase acts with a 50-fold lower substrate affinity and its only hexose substrate is glucose.
Glucokinase has a higher Km than Hexokinase, resulting in lower affinity. Glucokinase is deployed after we eat a meal in order to limit the amount of sugar absorbed, resulting in a lower blood sugar.
(G 6-P inhibits the activity of hexokinase.)
What is the committed step in Glycolysis?
Fructose 6-phosphate phosphorylated again to generate fructose 1,6-bisphosphate
Why is this (Phosphorylation of Fructose 6-phosphate) the committed step?
Fructose 1,6-bisphosphate can ONLY undergoe the reactions of glycolysis. Components can have other metabolic fates up to this point. (NO TURNING BACK)
Ten steps of Glycolysis?
- Hexokinase
- Phosphoglucose Isomerase
- Phosphofructokinase
- Aldolase
- Triphosphate isomerase
- Glyceraldehyde-3-phosphate Dehydrogenase
- Phosphoglycerate Kinase
- Phosphoglycerate Mutase
- Enolase
- Pyruvate Kinase
Thiamine pyrophosphate (TPP)
TPP is a coenzyme in the transfer of two-carbon units. It is required for catalysis by pyruvate decarboxylase in alcoholic fermentation.
Important feature of TPP?
The important part of TPP is the five-membered ring, in which a carbon is found between nitrogen and a sulfur. This carbon forms a carbanion and is extremely reactive, making it able to perform a nucleophilic attack on carbonyl groups, leading to decarboxylation of several compounds in different pathways.
Fetal Alcohol Syndrome,
The variety of injuries to a fetus caused by maternal consumption of alcohol.
First step of catabolism of ethanol by the body,
In catabolism of ethanol by the body, the first is conversion to acetaldehyde.
How is Fetal Alcohol Syndrome detected,
The level of acetaldehyde in the blood of a pregnant woman is the key to detecting this syndrome.
Where does acetaldehyde accumulate in the fetus?
The acetaldehyde is transferred across the placenta and it accumulates in the liver of the fetus.
Three reactions exhibit particularly large decreases in free energy; the enzymes that catalyze these reactions are sites of allosteric control
Hexokinase
Phosphofructokinase
Pyruvate Kinase
The steps catalyzed by hexokinase, phosphofructokinase, and pyruvate kinase are irreversible.
A. True
