Question 1

Which of the following diseases has not been successfully treated using the principles of enzyme inhibition?

Accepted Answer

A)  AIDS. 
B)  Lactose intolerance 
C)  Virus infection 
D)  Neither AIDS nor virus infection. 
E)  All of these have been successfully treated using enzyme inhibitors. 
A)  AIDS. 
B)  Lactose intolerance 
C)  Virus infection 
D)  Neither AIDS nor virus infection. 
E)  All of these have been successfully treated using enzyme inhibitors.

Question 2

First order kinetics means:

Accepted Answer

A)  The rate of a reaction is independent of the amount of reactant measured. 
B)  The rate of the reaction varies directly with the amount of reactant measured. 
C)  The rate of the reaction varies with the square of the amount of the reactant measured. 
D)  More information is needed to answer this question. 
E)  None of these is correct. 
A)  The rate of a reaction is independent of the amount of reactant measured. 
B)  The rate of the reaction varies directly with the amount of reactant measured. 
C)  The rate of the reaction varies with the square of the amount of the reactant measured. 
D)  More information is needed to answer this question. 
E)  None of these is correct.

Question 3

The Michaelis constant is

Accepted Answer

A)  the rate constant for the formation of the substrate-enzyme (E-S) complex. 
B)  the rate constant for the breakdown of the substrate-enzyme (E-S) complex to form free enzyme and substrate. 
C)  the rate constant for the breakdown of the substrate-enzyme (E-S) complex to form free enzyme and product. 
D)  a compilation of several rate constants for the reaction. 
A)  the rate constant for the formation of the substrate-enzyme (E-S) complex. 
B)  the rate constant for the breakdown of the substrate-enzyme (E-S) complex to form free enzyme and substrate. 
C)  the rate constant for the breakdown of the substrate-enzyme (E-S) complex to form free enzyme and product. 
D)  a compilation of several rate constants for the reaction.

Question 4

The kinetic order of a reaction

Accepted Answer

A)  can be determined by inspection from the coefficients of the balanced equation 
B)  must be determined experimentally 
C)  always depends on the concentration of enzyme 
D)  never depends on concentrations of reactants 
A)  can be determined by inspection from the coefficients of the balanced equation 
B)  must be determined experimentally 
C)  always depends on the concentration of enzyme 
D)  never depends on concentrations of reactants

Question 5

The Michaelis constant is

Accepted Answer

A)  related to the molecular weight of the enzyme 
B)  a measure of the resistance of the enzyme to denaturation 
C)  a reflection of the percentage of polar amino acids in the enzyme 
D)  a measure of how tightly the substrate is bound to the enzyme 
A)  related to the molecular weight of the enzyme 
B)  a measure of the resistance of the enzyme to denaturation 
C)  a reflection of the percentage of polar amino acids in the enzyme 
D)  a measure of how tightly the substrate is bound to the enzyme

Question 6

The reaction catalyzed by aspartate transcarbamoylase is

Accepted Answer

A)  the first step in the synthesis of amino acids. 
B)  the first step in the synthesis of fatty acids. 
C)  the first step in the synthesis of CTP and UTP. 
D)  is part of glycolysis. 
A)  the first step in the synthesis of amino acids. 
B)  the first step in the synthesis of fatty acids. 
C)  the first step in the synthesis of CTP and UTP. 
D)  is part of glycolysis.

Question 7

Which of the following are related for a given enzyme?

Accepted Answer

A)  Vmax, KM, and percentage of a-helix 
B)  Vmax, kcat, and percentage of b-sheet 
C)  Vmax, kcat, and turnover number 
D)  Vmax, KM, and molecular weight 
A)  Vmax, KM, and percentage of a-helix 
B)  Vmax, kcat, and percentage of b-sheet 
C)  Vmax, kcat, and turnover number 
D)  Vmax, KM, and molecular weight

Question 8

Which of the following is implied by induced fit between the enzyme's active site and the substrate?

Accepted Answer

A)  The enzyme is a flexible molecule. 
B)  An enzyme will work equally well with different substrates. 
C)  An active site can bind to different substrates. 
D)  The enzyme is a flexible molecule so different substrates can bind. 
E)  All of these 
A)  The enzyme is a flexible molecule. 
B)  An enzyme will work equally well with different substrates. 
C)  An active site can bind to different substrates. 
D)  The enzyme is a flexible molecule so different substrates can bind. 
E)  All of these

Question 9

The Michaelis constant determines the Vmax of an enzymatic reaction.

Accepted Answer

A) True 
 B)False

Question 10

Irreversible inhibitors of enzymatic reactions

Accepted Answer

A)  bind to the enzyme only at low temperatures. 
B)  affect only serine side chains. 
C)  react with the enzyme to produce a protein that is not enzymatically active and from which the original enzyme cannot be regenerated. 
D)  are bound to the enzyme by the lock-and-key mechanism. 
A)  bind to the enzyme only at low temperatures. 
B)  affect only serine side chains. 
C)  react with the enzyme to produce a protein that is not enzymatically active and from which the original enzyme cannot be regenerated. 
D)  are bound to the enzyme by the lock-and-key mechanism.

Question 11

Given the rate law,rate = k[A][B],the overall reaction order is

Accepted Answer

A)  zero 
B)  one 
C)  two 
D)  cannot be determined 
A)  zero 
B)  one 
C)  two 
D)  cannot be determined

Question 12

The fundamental difference between competitive and noncompetitive inhibition is

Accepted Answer

A)  the degree of cooperativity of the reaction 
B)  the size of the active site of the enzyme 
C)  the manner of binding of substrate to the enzyme 
D)  the manner of binding of inhibitor to the enzyme 
A)  the degree of cooperativity of the reaction 
B)  the size of the active site of the enzyme 
C)  the manner of binding of substrate to the enzyme 
D)  the manner of binding of inhibitor to the enzyme

Question 13

It is important that at physiological conditions,enzymes work at Vmax.

Accepted Answer

A) True 
 B)False

Question 14

The sign of Gibb's Free Energy is positive ("+") when energy is released.

Accepted Answer

A) True 
 B)False

Question 15

To study the nature of an enzyme,Vmax is not as good a measurement as the catalytic rate constant kcat because:

Accepted Answer

A)  The Vmax is not a true constant since it depends on the concentration of enzyme 
B)  The Vmax cannot be measured 
C)  The Vmax is only valid for allosteric enzymes 
D)  none of these 
A)  The Vmax is not a true constant since it depends on the concentration of enzyme 
B)  The Vmax cannot be measured 
C)  The Vmax is only valid for allosteric enzymes 
D)  none of these

Question 16

Which of the following is most directly related to the speed of a reaction?

Accepted Answer

A)  The temperature 
B)  The DG0 of the reaction 
C)  The DG of the reaction 
D)  The DG0‡ of the reaction 
E)  None of these is correct. 
A)  The temperature 
B)  The DG0 of the reaction 
C)  The DG of the reaction 
D)  The DG0‡ of the reaction 
E)  None of these is correct.

Question 17

Exhibit 6A This is a reaction going on in your muscle cells right this very minute:
  The enzyme triose phosphate isomerase catalyzes this reaction in the forward direction as part of the glycolytic pathway.It follows simple Michaelis-Menten kinetics:
  Typical cellular concentrations: triose phosphate isomerase = 0.1 nM
Dihydroxyacetone phosphate = 5 µM glyceraldehyde-3-phosphate = 2 µM
Refer to Exhibit 6A.What is the equilibrium constant for the enzyme-catalyzed reaction?

Accepted Answer

A)  0.9 
B)  1.1 
C)  2.5 
D)  Cannot be determined from the information provided. 
A)  0.9 
B)  1.1 
C)  2.5 
D)  Cannot be determined from the information provided.

Question 18

What effect is seen on a Lineweaver-Burk graph when a mixed-type inhibitor is added?

Accepted Answer

A)  The y-intercept is changed, but not change the slope of the line. 
B)  The slope of the line is changed, but not the y-intercept. 
C)  Both the y-intercept and the slope of the line are changed. 
D)  Neither the y-intercept not the slope of the line is changed. 
A)  The y-intercept is changed, but not change the slope of the line. 
B)  The slope of the line is changed, but not the y-intercept. 
C)  Both the y-intercept and the slope of the line are changed. 
D)  Neither the y-intercept not the slope of the line is changed.

Exam 6: The Behavior of Proteins: Enzymes

Which of the following diseases has not been successfully treated using the principles of enzyme inhibition?

First order kinetics means:

The Michaelis constant is

The kinetic order of a reaction

The Michaelis constant is

The reaction catalyzed by aspartate transcarbamoylase is

Which of the following are related for a given enzyme?

Which of the following is implied by induced fit between the enzyme's active site and the substrate?

The Michaelis constant determines the Vmax of an enzymatic reaction.

Irreversible inhibitors of enzymatic reactions

Given the rate law,rate = k[A][B],the overall reaction order is

The fundamental difference between competitive and noncompetitive inhibition is

It is important that at physiological conditions,enzymes work at Vmax.

The sign of Gibb's Free Energy is positive ("+") when energy is released.

To study the nature of an enzyme,Vmax is not as good a measurement as the catalytic rate constant kcat because:

Which of the following is most directly related to the speed of a reaction?

What effect is seen on a Lineweaver-Burk graph when a mixed-type inhibitor is added?

Biochemistry and the Organization of Cells

Water: The Solvent for Biochemical Reactions

Amino Acids and Peptides

The Three-Dimensional Structure of Proteins

Protein Purification and Characterization Techniques

The Behavior of Proteins: Enzymes, Mechanisms, and Control

Lipids and Proteins Are Associated in Biological Membranes

Nucleic Acids: How Structure Conveys Information

Biosynthesis of Nucleic Acids: Replication

Transcription of the Genetic Code: Biosynthesis of Rna

Protein Synthesis: Translation of the Genetic Message

Nucleic Acid Biotechnology Techniques

Viruses, Cancer, and Immunology

The Importance of Energy Changes and Electron Transfer in Metabolism

Carbohydrates

Glycolysis

Storage Mechanisms and Control in Carbohydrate Metabolism

The Citric Acid Cycle

Electron Transport and Oxidative Phosphorylation

Lipid Metabolism

Photosynthesis

The Metabolism of Nitrogen

Integration of Metabolism: Cellular Signaling

Filters

The Michaelis constant determines the V_max of an enzymatic reaction.

It is important that at physiological conditions,enzymes work at V_max.

To study the nature of an enzyme,V_max is not as good a measurement as the catalytic rate constant k_cat because: