Question 1

Which statement is false about the Entner-Doudoroff pathway?

Accepted Answer

A)  It produces less ATP per glucose molecule than glycolysis. 
B)  Organisms that have this pathway use it only under conditions of low glyceraldehyde 3-phosphate isomerase concentrations. 
C)  It is useful for bacteria that do not have PFK-1. 
D)  The pathway produces pyruvate and glyceraldehyde 3-phosphate. 
E)  It enables some bacteria to survive on gluconate and other organic acids that cannot be metabolized via glycolysis. 
A)  It produces less ATP per glucose molecule than glycolysis. 
B)  Organisms that have this pathway use it only under conditions of low glyceraldehyde 3-phosphate isomerase concentrations. 
C)  It is useful for bacteria that do not have PFK-1. 
D)  The pathway produces pyruvate and glyceraldehyde 3-phosphate. 
E)  It enables some bacteria to survive on gluconate and other organic acids that cannot be metabolized via glycolysis. B

Question 2

The enzyme that catalyzes the conversion of pyruvate to lactate is .

Accepted Answer

A)  lactate reductase 
B)  pyruvate kinase 
C)  lactoenolpyruvate 
D)  lactate dehydrogenase 
A)  lactate reductase 
B)  pyruvate kinase 
C)  lactoenolpyruvate 
D)  lactate dehydrogenase D

Question 3

There are four enzymes that can catalyze the first step of glycolysis. They are hexokinases I, II and III and glucokinase hexokinase IV). Hexokinases I, II and III have Km values near 0.1 mM. Glucokinase has a Km range of 2-5 mM. If after a heavy meal the blood glucose level rises to 8 mM which statement will be true?

Accepted Answer

A)  At this high blood glucose level all four hexokinases are saturated with substrate. 
B)  Hexokinases I, II and III are catalyzing at their maximum rate, but glucokinase can still respond to increases in blood glucose levels. 
C)  None of the enzymes is saturated. All of them help to increase the rate of glycolysis. 
D)  The flux through glucokinase will be extremely low. The only significant catalysis is done by hexokinases I, II and III. 
A)  At this high blood glucose level all four hexokinases are saturated with substrate. 
B)  Hexokinases I, II and III are catalyzing at their maximum rate, but glucokinase can still respond to increases in blood glucose levels. 
C)  None of the enzymes is saturated. All of them help to increase the rate of glycolysis. 
D)  The flux through glucokinase will be extremely low. The only significant catalysis is done by hexokinases I, II and III. B

Question 4

A patient is found to be deficient in the enzyme galactose 1-phosphate uridylyltransferase. Specifically due to this deficiency what might a doctor recommend?

Accepted Answer

A)  avoid all strenuous exercise 
B)  eat a fat-free diet 
C)  increase intake of vitamin C 
D)  avoid ingestion of milk and milk products 
A)  avoid all strenuous exercise 
B)  eat a fat-free diet 
C)  increase intake of vitamin C 
D)  avoid ingestion of milk and milk products

Question 5

Arsenate

Accepted Answer

A)  competes with NAD+ for the binding site in 1,3-bisphosphoglycerate. 
B)  competes with phosphate for its binding site in glyceraldehyde 3-phosphate dehydrogenase. 
C)  produces a stable analog of 1,3-bisphosphoglycerate. 
D)  All of the above 
A)  competes with NAD+ for the binding site in 1,3-bisphosphoglycerate. 
B)  competes with phosphate for its binding site in glyceraldehyde 3-phosphate dehydrogenase. 
C)  produces a stable analog of 1,3-bisphosphoglycerate. 
D)  All of the above

Question 6

Glyceraldehyde 3-phosphate and dihydroxyacetone phosphate are substrates in an oxidation and phosphorylation reaction, which yields a high energy mixed anhydride.

Accepted Answer

A) True 
 B)False

Question 7

The slowing of glycolysis in the presence of oxygen is called the effect.

Accepted Answer

A)  Bohr 
B)  Michaelis-Menton 
C)  Pastuer 
D)  Pauling 
A)  Bohr 
B)  Michaelis-Menton 
C)  Pastuer 
D)  Pauling

Question 8

In strenuously working muscle the pH decreases. This inhibits the activity of PFK-1 and glycolysis slows. Why would it be desirable to slow glycolysis when the demand for ATP is high?

Accepted Answer

A)  Inhibition of PFK-1 allows for the complete oxidation of pyruvate via the citric acid cycle. 
B)  Slowing glycolysis slows the rate of decrease in pH. A low pH can be harmful and potentially fatal. 
C)  The less active form of PFK-1 is a potent allosteric activator of creatine, so even though glycolysis is slowed, ATP production is actually increased by the activation of creatine. 
D)  As PFK-1 is inhibited, its isozyme, PFK-2 is activated. PFK-2 is functional at a much lower pH than PFK-1. 
A)  Inhibition of PFK-1 allows for the complete oxidation of pyruvate via the citric acid cycle. 
B)  Slowing glycolysis slows the rate of decrease in pH. A low pH can be harmful and potentially fatal. 
C)  The less active form of PFK-1 is a potent allosteric activator of creatine, so even though glycolysis is slowed, ATP production is actually increased by the activation of creatine. 
D)  As PFK-1 is inhibited, its isozyme, PFK-2 is activated. PFK-2 is functional at a much lower pH than PFK-1.

Question 9

Which of the following is not a metabolically irreversible enzymatic reaction of glycolysis?

Accepted Answer

A)  pyruvate kinase reaction 
B)  PFK-1 reaction 
C)  hexokinase/Glucokinase reaction 
D)  None of the above 
A)  pyruvate kinase reaction 
B)  PFK-1 reaction 
C)  hexokinase/Glucokinase reaction 
D)  None of the above

Question 10

More than one step in the glycolytic pathway is subject to regulation. It might seem most efficient to regulate only the first step of a pathway to avoid buildup of intermediates and to conserve materials and energy. Why is the first step of glycolysis not the only regulated step?

Accepted Answer

A)  Some sugars can enter the glycolytic pathway beyond the first step. If steps other than step one were not regulated, the breakdown of these sugars would be essentially uncontrolled. 
B)  Having more than one regulated step in the pathway allows for feedback inhibition. 
C)  Control of a single step in a reaction pathway is difficult because the concentrations of enzymes in cells are very low. Itʹs easier to control more than one enzyme. 
D)  All the ATP in a cell would be depleted very quickly if only the first step of glycolysis were regulated. 
A)  Some sugars can enter the glycolytic pathway beyond the first step. If steps other than step one were not regulated, the breakdown of these sugars would be essentially uncontrolled. 
B)  Having more than one regulated step in the pathway allows for feedback inhibition. 
C)  Control of a single step in a reaction pathway is difficult because the concentrations of enzymes in cells are very low. Itʹs easier to control more than one enzyme. 
D)  All the ATP in a cell would be depleted very quickly if only the first step of glycolysis were regulated.

Question 11

The genetic disorder galactosemia can cause in infants.

Accepted Answer

A)  inability to properly digest milk due to its galactose content 
B)  jaundice 
C)  damage to the nervous system 
D)  liver damage 
E)  All of the above 
A)  inability to properly digest milk due to its galactose content 
B)  jaundice 
C)  damage to the nervous system 
D)  liver damage 
E)  All of the above

Question 12

PFK-2 and fructose 2,6-bisphosphatase are two names for the same enzyme. The name PFK-2 is used for the enzymeʹs catalysis of the phosphorylation of fructose 6-phosphate to fructose 2,6-bisphosphate. The name fructose 2,6-bisphosphatase is used for its catalysis of the reverse reaction. What is unique about this enzyme that makes it logical to use two names?

Accepted Answer

A)  It is one of very few enzymes that can catalyze both the forward and reverse reactions. 
B)  The enzyme is a monomer when catalyzing the phosphorylation reaction and a dimer when catalyzing the reverse reaction. 
C)  The forward and reverse reactions occur in different compartments within the cell, so a different name is used for each activity. 
D)  The enzyme is bifunctional. The forward and reverse reactions are catalyzed by different sites on the same enzyme. 
A)  It is one of very few enzymes that can catalyze both the forward and reverse reactions. 
B)  The enzyme is a monomer when catalyzing the phosphorylation reaction and a dimer when catalyzing the reverse reaction. 
C)  The forward and reverse reactions occur in different compartments within the cell, so a different name is used for each activity. 
D)  The enzyme is bifunctional. The forward and reverse reactions are catalyzed by different sites on the same enzyme.

Question 13

Lactic acid produced by certain bacteria is used to curdle milk during cheese-making.

Accepted Answer

A) True 
 B)False

Question 14

Under aerobic conditions yeast cells convert pyruvate to ethanol and carbon dioxide.

Accepted Answer

A) True 
 B)False

Question 15

An increase in blood insulin concentration increases the rate of glucose uptake in adipose tissue and striated muscle cells.

Accepted Answer

A) True 
 B)False

Question 16

Substrate level phosphorylation

Accepted Answer

A)  describes the conversion of ADP into ATP with the addition of inorganic phosphate every place throughout the cell. 
B)  describes the formation of ADP by phosphoryl group transfer from 1,3 bisphosphoglycerate. 
C)  is the formation of ATP by phosphoryl group transfer from a higher energy compound. 
D)  Both A and C 
A)  describes the conversion of ADP into ATP with the addition of inorganic phosphate every place throughout the cell. 
B)  describes the formation of ADP by phosphoryl group transfer from 1,3 bisphosphoglycerate. 
C)  is the formation of ATP by phosphoryl group transfer from a higher energy compound. 
D)  Both A and C

Question 17

In the presence of arsenate poisoning

Accepted Answer

A)  ATP production proceeds via a reaction that involves 1,3-bisphosphoglycerate. 
B)  glycolysis is interrupted. 
C)  a net production of 2 molecules of ATP occurs. 
D)  All of the above 
E)  None of the above 
A)  ATP production proceeds via a reaction that involves 1,3-bisphosphoglycerate. 
B)  glycolysis is interrupted. 
C)  a net production of 2 molecules of ATP occurs. 
D)  All of the above 
E)  None of the above

Question 18

Which of the following enzymatic reactions are control points for glycolysis?

Accepted Answer

A)  glucose 6-phosphate isomerase 
B)  aldolase 
C)  Both A and B 
D)  Neither A nor B 
A)  glucose 6-phosphate isomerase 
B)  aldolase 
C)  Both A and B 
D)  Neither A nor B

Question 19

Which substance causes muscles to ache during strenuous exercise?

Accepted Answer

A)  pyruvic acid 
B)  lactose dehydrogenase 
C)  lactate ion 
D)  lactic acid 
A)  pyruvic acid 
B)  lactose dehydrogenase 
C)  lactate ion 
D)  lactic acid

Question 20

Glucagon is a pancreatic hormone that is produced in response to low blood sugar levels. At high glucagon concentrations glycolysis is slowed.

Accepted Answer

A) True 
 B)False

Exam 11: Glycolysis

Which statement is false about the Entner-Doudoroff pathway?

The enzyme that catalyzes the conversion of pyruvate to lactate is .

A patient is found to be deficient in the enzyme galactose 1-phosphate uridylyltransferase. Specifically due to this deficiency what might a doctor recommend?

Arsenate

Glyceraldehyde 3-phosphate and dihydroxyacetone phosphate are substrates in an oxidation and phosphorylation reaction, which yields a high energy mixed anhydride.

The slowing of glycolysis in the presence of oxygen is called the effect.

In strenuously working muscle the pH decreases. This inhibits the activity of PFK-1 and glycolysis slows. Why would it be desirable to slow glycolysis when the demand for ATP is high?

Which of the following is not a metabolically irreversible enzymatic reaction of glycolysis?

More than one step in the glycolytic pathway is subject to regulation. It might seem most efficient to regulate only the first step of a pathway to avoid buildup of intermediates and to conserve materials and energy. Why is the first step of glycolysis not the only regulated step?

The genetic disorder galactosemia can cause in infants.

Lactic acid produced by certain bacteria is used to curdle milk during cheese-making.

Under aerobic conditions yeast cells convert pyruvate to ethanol and carbon dioxide.

An increase in blood insulin concentration increases the rate of glucose uptake in adipose tissue and striated muscle cells.

Substrate level phosphorylation

In the presence of arsenate poisoning

Which of the following enzymatic reactions are control points for glycolysis?

Which substance causes muscles to ache during strenuous exercise?

Glucagon is a pancreatic hormone that is produced in response to low blood sugar levels. At high glucagon concentrations glycolysis is slowed.

Introduction to Biochemistry

Water

Amino Acids and the Primary Structures of Proteins

Proteins: Three-Dimensional Structure and Function

Properties of Enzymes

Mechanisms of Enzymes

Coenzymes and Vitamins

Carbohydrates

Lipids and Membranes

Introduction to Metabolism

Gluconeogenesis, the Pentose Phosphate Pathway, and Glycogen Metabolism

The Citric Acid Cycle

Electron Transport and Oxidative Phosphorylation

Photosynthesis

Lipid Metabolism

Amino Acid Metabolism

Nucleotide Metabolism

Nucleic Acids

Dna Replication, Repair, and Recombination

Transcription and Rna Processing

Protein Synthesis

Recombinant Dna Technology

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