Deck 9: Chemotrophic Energy Metabolism: Glycolysis and Fermentation

Question 1

Which of the following glycolytic enzymes associates with mitochondria to coordinate glycolysis and respiration?

A)hexokinase
B)aldolase
C)phosphoglycerokinase
D)pyruvate kinase
E)None of the above are correct.

Answer 1

A

Question 2

Consider the three phases of glycolysis:
(1)preparation and cleavage (Gly-1 to Gly-5)
(2)oxidation (Gly-6 to Gly-7)
(3)pyruvate formation (Gly-8 to Gly-10)
Which of these phases produces ATP?

A)1
B)2
C)3
D)1 and 2
E)2 and 3

Answer 2

2 and 3

Question 3

Which of the following is a coenzyme?

A)NAD
B)NADP
C)FAD
D)CoA
E)All are coenzymes.

Answer 3

E

Question 4

NAD⁺

A)is derived from vitamin E.
B)is an electron source for biological oxidation reactions.
C)is a coenzyme acceptor of electrons and a hydrogen ion.
D)releases a phosphate to become NADH.
E)is the reduced form of the B vitamin niacin.

Question 5

During glycolysis,aldolase catalyzes the breakdown of fructose-1,6 bisphosphate to produce

A)phosphoenolpyruvate.
B)dihydroxyacetone phosphate.
C)fructose-6-phosphate.
D)A and B.
E)B and C.

Question 6

Anabolic pathways

A)increase molecular order.
B)are endergonic.
C)decrease entropy.
D)can be stimulated by anabolic hormones.
E)All of the above are correct.

Question 7

Which of the following statements best describes the role of NAD⁺/NADH in glycolysis?

A)NADH is used to directly create the phosphoanhydride bonds in ATP.
B)NAD⁺ accepts electrons.
C)NADH accepts electrons during fermentation.
D)NADH is used primarily in substrate-level phosphorylation.
E)All of the above are correct.

Question 8

Oxygen is toxic to

A)obligate anaerobes.
B)obligate aerobes.
C)cancer cells.
D)facultative organisms.
E)All of the above.

Question 9

A phosphoanhydride bond

A)is a high-energy bond.
B)has a standard free energy of hydrolysis of −7.3 kcal/mol.
C)is broken by hydrolysis.
D)links two phosphate groups.
E)All of the above are correct.

Question 10

During the process of glycolysis,which of the following substrates donates electrons to NAD⁺ and adds P_i to form 1,3-bisphosphoglycerate?

A)3-phosphoglycerate
B)2-phosphoglycerate
C)glyceraldehyde-3-phosphate
D)glucose
E)glucose-6-phosphate

Question 11

Oxidation reactions in biological systems generally involve

A)addition of electrons and hydrogen ions.
B)loss of electrons and hydrogen ions.
C)addition of electrons and loss of hydrogen ions.
D)loss of electrons and addition of hydrogen ions.
E)loss of electrons and either addition or loss of hydrogen ions.

Question 12

The gross output of ATP from glycolysis is ________,whereas the net output of ATP is ________.

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

Question 13

Consider the following list of phosphorylated compounds with their free energies of phosphate hydrolysis:
Glucose-1-phosphate: -5.0 kcal/mol
PEP: -14.8 kcal/mole
ATP: -7.3 kcal/mol
Which of these molecules could phosphorylate an unknown compound whose free energy of phosphate hydrolysis is -10.3kcal/mol?

A)Glucose-1-phosphate only
B)PEP only
C)ATP only
D)ATP and PEP
E)All three could phosphorylate the unknown compound.

Question 14

The negatively charged phosphates of ATP influence one another by

A)positron emission.
B)charge repulsion.
C)resonance destabilization.
D)standard free energy.
E)All of the above are correct.

Question 15

The breakdown of glucose to pyruvate by a cell is an example of what type of reaction?

A)anabolic
B)aerobic
C)catabolic
D)apoptotic
E)synthetic

Question 16

How many enzymes are involved in glycolysis of glucose to pyruvate?

A)3
B)6
C)8
D)10
E)12

Question 17

During the first phase of glycolysis,phosphate forms what type of bond with glucose?

A)phosphoester
B)phosphoanhydride
C)hydrogen
D)ionic
E)diphosphate

Question 18

Aldolase breaks down fructose-1,6-bisphosphate into two trioses that are

A)identical.
B)each doubly phosphorylated.
C)identical and each doubly phosphorylated.
D)different and each doubly phosphorylated.
E)different and each singly phosphorylated.

Question 19

The ATP "high-energy" or "energy-rich" bonds are which of the following types of bond?

A)phosphoester
B)phosphoanhydride
C)hydrogen
D)ionic
E)monophosphate

Question 20

An anabolic reaction usually

A)yields energy.
B)requires energy.
C)involves no change in energy.
D)is degradative,regardless of energy change.
E)decreases molecular order.

Question 21

Glycolytic enzymes are known to function in each of the following processes except

A)transcriptional regulation.
B)gluconeogenesis.
C)apoptosis regulation.
D)oxygen reduction to form water.
E)coordination of glycolysis and mitochondrial respiration.

Question 22

Although pyruvate is the end product of glycolysis and no more ATP is generated by fermentation of pyruvate to ethanol,yeast produce ethanol under anaerobic conditions because

A)pyruvate export requires more energy than ethanol export.
B)electrons (and protons)are then added to ethanol to make lactate.
C)transfer of electrons from NADH to pyruvate to make ethanol regenerates NAD⁺,which is necessary for new rounds of glycolysis to proceed.
D)glycolysis substrate-level phosphorylation changes pyruvate to ethanol.
E)pyruvate to ethanol fermentation decreases deleterious CO₂ levels.

Question 23

A temporary oxygen deficit during strenuous exercise causes a muscle to

A)synthesize muscle proteins in response to steroid hormone stimulation.
B)synthesize glycogen.
C)ferment pyruvate to lactate.
D)switch to aerobic glycolysis.
E)synthesize more NAD⁺.

Question 24

Glycolytic enzymes have been found to have roles in all of the following except

A)transcriptional repression.
B)apoptosis inhibition.
C)transcriptional activator.
D)GTP hydrolysis.
E)stimulation of cell migration.

Question 25

Pyruvate can be a substrate or product involved in each of the following except

A)fermentation.
B)aerobic glycolysis.
C)gluconeogenesis.
D)amino acid biosynthesis.
E)Pyruvate can be involved in all of the above.

Question 26

Allosteric regulation of key enzymes in glycolytic and gluconeogenesis pathways may involve each of the following except

A)activating the enzyme activity.
B)inhibiting the enzyme activity.
C)binding of the allosteric regulator molecule to directly compete with substrate binding in the enzyme active site.
D)binding of the allosteric regulator molecule to a site on the enzyme other than the active site.
E)Any of the above may be involved.

Question 27

Which glycolytic enzyme uses ATP to phosphorylate glucose?

A)alcohol dehydrogenase
B)phosphoglucoisomerase
C)aldolase
D)hexokinase
E)pyruvate kinase

Question 28

The phosphate group that is removed from PEP when it becomes pyruvate

A)is added to NAD⁺ to make NADP.
B)is released as Pi.
C)is added to ADP to make ATP.
D)is added to glyceraldehyde-3-phosphate to make 1,3-bisphosphoglycerate.
E)is added to fructose-6-phosphate to make fructose-1,6-bisphosphate.

Question 29

During the conversion of 1,3-bisphosphoglycerate to 3-phosphoglycerate and phosphoenolpyruvate,a phosphate group is added to ATP to generate ATP.The mechanism for ATP production in this reaction is

A)substrate-level phosphorylation.
B)product-level phosphorylation.
C)oxidative phosphorylation.
D)anabolic phosphorylation.
E)aerobic phosphorylation.

Question 30

Fermentation directly

A)generates ATP.
B)regenerates NAD⁺ from NADH.
C)regenerates NADH from NAD⁺.
D)produces acetyl CoA.
E)initiates gluconeogenesis.

Question 31

Positron emission tomography (PET)of a patient who has consumed the radiotracer fluorodeoxyglucose reveals tumors because

A)any radioisotope accumulates in tumor cells.
B)cancer cells accumulate fluorodeoxyglucose because they consume excessive amounts of glucose through aerobic glycolysis.
C)the fluorodeoxyglucose labels cells killed by the PET treatment.
D)the fluorodeoxyglucose labels only the normal tissue because cancer cells cannot metabolize glucose.
E)the fluorodeoxyglucose associates with the anti-tumor drugs being used for treatment.

Question 32

In animal cells,glycolysis and gluconeogenesis are regulated to ensure that both processes are reciprocally active.This regulation involves each of the following compounds except

A)NADH.
B)fructose-2,6-bisphosphate.
C)AMP.
D)acetyl CoA.
E)cAMP.

Question 33

Cells can store energy in each of the following molecules except

A)ATP.
B)GTP.
C)creatine phosphate.
D)NADH.
E)Cells can store energy in all of the above molecules.

Question 34

Each of the following can be the final electron acceptor in bacterial aerobic or anaerobic respiration except

A)sulfur.
B)hydrogen ions.
C)Fe³⁺.
D)oxygen.
E)pyruvate.

Question 35

Each of the following is a substrate for glycolysis except

A)galactose.
B)mannose.
C)lactose.
D)fructose.
E)All are substrates for glycolysis.

Question 36

Which of the following is not a product of fermentation?

A)lactate
B)CO₂
C)ethanol
D)NAD⁺
E)glycogen

Question 37

Glucose transported into human cells can be transformed into all of the following except

A)sucrose for energy production.
B)carbon dioxide and water by aerobic respiration.
C)lactate in the absence of oxygen.
D)glycogen for energy storage.
E)acetyl CoA to make body fat.

Question 38

The process of gluconeogenesis converts pyruvate or lactate into

A)sucrose.
B)fructose.
C)mannose.
D)glucose.
E)gluconate.

Question 39

In the first step of glycolysis,glucose can be phosphorylated to glucose-6-phosphate,because

A)a phosphoanhydride bond has higher energy of hydrolysis than is required for formation of a phosphoester bond.
B)transfer of a phosphate from ATP to glucose is endergonic.
C)the reaction does not require an enzyme.
D)the reaction is highly reversible.
E)All of the above are correct.

Question 40

Each of the following is fermentation products except

A)ethanol.
B)lactate.
C)propionate.
D)acetyl CoA.
E)butyrate.

Question 41

Three of the ten glycolysis enzyme reactions are not simply reversed in gluconeogenesis and require different enzymes because

A)these three glycolytic enzymes cannot catalyze the reaction in the reverse direction under any circumstances.
B)these three glycolytic steps are the most highly exergonic and thermodynamically difficult to reverse.
C)NAD⁺ needs to be generated from NADH at each of these three steps.
D)all three steps require hydrolysis of ATP for gluconeogenesis.
E)these three glycolytic enzymes are not present in the cells performing gluconeogenesis.

Question 42

Isotopic labeling of a specific substrate carbon with ¹³C,which has an extra neutron,is particularly useful for investigating biochemical pathways because

A)the presence of the radioisotope greatly accelerates the pathway,which makes it easier to study.
B)the position of the labeled carbon can be traced through products of the pathway to characterize the pathway reactions.
C)the radioisotope blocks each pathway at a specific step.
D)the radioisotope readily exchanges neutrons so that all neighboring carbons become labeled and easier to detect with NMR.
E)radiolabels generally are easier to track in cells than fluorescent labels.

Question 43

Mammalian tumor cells that increase glycolysis even in the presence of oxygen increase expression of one isoform of the glycolytic enzyme ________,the first enzyme in the glycolytic pathway.

Question 44

________ organisms can function in an aerobic or anaerobic environment.

Question 45

Oxidation is the removal of ________,which usually is accompanied by removal of protons in a process called ________ in biological systems.

Question 46

Glycolysis is a ________-step reaction sequence that converts glucose into ________ and generates a net total of ________ ATPs.

Question 47

Galactosemia is a disease caused by a genetic defect that affects an individual's ability to correctly metabolize galactose for use in the glycolytic pathway,but has no effect on metabolism of starch and glycogen,or on glycolysis.Galactosemia results in high galactose levels in the blood and accumulation of galactose-1-phosphate in the tissues.
a)If you were a physician treating a person with this genetic disorder,in addition to galactose,what other dietary sugar would you recommend the patient not consume to avoid high galactose levels in the blood?
b)Why would infants be more likely than adults to have high blood galactose levels associated with galactosemia?
c)Suggest a reason for the observation that galactosemia is more common than fructosemia?
d)Propose possible candidates for the defective enzyme that causes galactosemia.

Question 48

Reduction is the addition of ________,which usually is accompanied by addition of protons in a process called ________ in biological systems.

Question 49

The loss of a(n)________ increases entropy during hydrolysis of ATP.

Question 50

The coenzyme ________ donates ________ to ferment pyruvate into lactate or ethanol.

Question 51

________ is the most common coenzyme involved in energy metabolism.

Question 52

The ________ links lactate produced by fermentation in muscle cells with gluconeogenesis in liver cells.

Question 53

Individuals with diabetes (diabetes mellitus),in which blood glucose levels can be toxically high,are often recommended to avoid consuming sucrose (table sugar).
a)Why is sucrose not recommended for diabetics?
b)Why would diabetics be urged to avoid foods that are high in starch?

Question 54

When studying carbohydrate metabolism in a newly identified bacterial species,you find the bacteria grow exclusively on the carbohydrate sucrose.
a)Hypothesize whether the bacteria use glycolysis or a novel pathway for harnessing energy.
b)For what enzyme would you assay the bacteria to test your hypothesis?

Question 55

Compare and contrast ethanol and lactic acid fermentation pathways.

Question 56

________ stabilization lowers free energy,because extra electrons are delocalized over all possible bonds.

Question 57

The three reasons that phosphoanhydride bond hydrolysis is highly exergonic are: ________ between the bonded phosphate groups and increased ________ and ________ of both products of hydrolysis.

Question 58

________ is the enzyme that hydrolyzes ________ in dairy products into glucose and galactose.Absence of the enzyme may cause cramps and diarrhea in a condition called ________.

Question 59

Human erythrocytes have no mitochondria.The rare inherited metabolic disorder that results from pyruvate kinase deficiency is particularly destructive to erythrocytes and causes hemolytic anemia.
a)Suggest a reason for increased erythrocyte death in the presence of pyruvate kinase deficiency.
b)Suggest a reason for the low incidence of mutations in human glycolytic enzymes.

Question 60

________ is the mechanism by which a phosphate is directly transferred to ADP to form ATP.