Question 1

The steady state of an enzyme reaction is the following:

Accepted Answer

A)  The rate observed just after mixing the enzyme and substrate. 
B)  The rate observed and Vmax. 
C)  The rate of product formation. 
D)  The state which exists when E-S complex is forming as fast as it is breaking down. 
E)  The state which exists when substrate concentration equals KM. 
A)  The rate observed just after mixing the enzyme and substrate. 
B)  The rate observed and Vmax. 
C)  The rate of product formation. 
D)  The state which exists when E-S complex is forming as fast as it is breaking down. 
E)  The state which exists when substrate concentration equals KM.

Question 2

If an inhibitor changes the slope of the Lineweaver-Burk graph,but not the x-intercept,it is this type of inhibition:

Accepted Answer

A)  Competitive. 
B)  Non-competitive. 
C)  Mixed Inhibition (uncompetitive inhibition). 
D)  You cannot tell from the data given. 
E)  More than one answer is correct. 
A)  Competitive. 
B)  Non-competitive. 
C)  Mixed Inhibition (uncompetitive inhibition). 
D)  You cannot tell from the data given. 
E)  More than one answer is correct.

Question 3

Competitive inhibitors have this effect:

Accepted Answer

A)  Modifying the KM value. 
B)  Changing the value for Vmax. 
C)  Interfering with substrate binding. 
D)  This type of inhibitor both changes the KM and interferes with substrate binding. 
E)  All of these are correct. 
A)  Modifying the KM value. 
B)  Changing the value for Vmax. 
C)  Interfering with substrate binding. 
D)  This type of inhibitor both changes the KM and interferes with substrate binding. 
E)  All of these are correct.

Question 4

All catalysts work by lowering the activation energy for a reaction.

Accepted Answer

A) True 
 B)False

Question 5

Non-competitive inhibitors have this effect:

Accepted Answer

A)  Modifying the KM value. 
B)  Changing the value for Vmax. 
C)  Interfering with substrate binding. 
D)  This type of inhibitor both changes the Vmax and interferes with substrate binding. 
E)  All of these are correct. 
A)  Modifying the KM value. 
B)  Changing the value for Vmax. 
C)  Interfering with substrate binding. 
D)  This type of inhibitor both changes the Vmax and interferes with substrate binding. 
E)  All of these are correct.

Question 6

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."Restrainin" is an inhibitor of triose phosphate isomerase.When it is added to cells at a concentration of 0.4 nM,the enzyme's apparent KM for the substrate is altered to 100 µM,but the Vmax is unchanged.

Accepted Answer

A)  This is a competitive inhibitor. 
B)  This is an uncompetitive inhibitor. 
C)  This is a noncompetitive inhibitor. 
D)  This is an irreversible inhibitor. 
A)  This is a competitive inhibitor. 
B)  This is an uncompetitive inhibitor. 
C)  This is a noncompetitive inhibitor. 
D)  This is an irreversible inhibitor.

Question 7

The KM of hexokinase for glucose = 0.15 mM and for fructose,KM = 1.5 mM.Which is the preferred substrate?

Accepted Answer

A)  Glucose. 
B)  Fructose. 
C)  Neither substrate is preferred over the other. 
D)  You cannot tell from the data given. 
E)  None of these answers is correct. 
A)  Glucose. 
B)  Fructose. 
C)  Neither substrate is preferred over the other. 
D)  You cannot tell from the data given. 
E)  None of these answers is correct.

Question 8

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 uncatalyzed 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 9

What effect is seen on a Lineweaver-Burk graph when a competitive 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.

Question 10

If the y-intercept of a Lineweaver-Burk plot = 1.91 (sec/millimole) and the slope = 75.3 L/sec,KM equals:

Accepted Answer

A)  0.0254 millimolar (mM). 
B)  0.523 millimolar (mM). 
C)  5.23 millimolar (mM). 
D)  39.4 millimolar (mM). 
E)  75.3 millimolar (mM). 
A)  0.0254 millimolar (mM). 
B)  0.523 millimolar (mM). 
C)  5.23 millimolar (mM). 
D)  39.4 millimolar (mM). 
E)  75.3 millimolar (mM).

Question 11

The substrate will only bind to the enzyme when the shapes fit together rigidly.

Accepted Answer

A) True 
 B)False

Question 12

A noncompetitive inhibitor

Accepted Answer

A)  binds to the enzyme at a site other than the active site 
B)  is structurally related to the substrate 
C)  does not affect the value of Vmax 
D)  decreases the value of KM 
A)  binds to the enzyme at a site other than the active site 
B)  is structurally related to the substrate 
C)  does not affect the value of Vmax 
D)  decreases the value of KM

Question 13

Most enzyme reactions display first order kinetics for the individual substrates when the substrate concentration is low.

Accepted Answer

A) True 
 B)False

Question 14

When an enzyme is saturated with substrates,

Accepted Answer

A)  it will display zero-order kinetics. 
B)  it will display first-order kinetics. 
C)  it will display second-order kinetics. 
D)  it will denature and cease to function. 
A)  it will display zero-order kinetics. 
B)  it will display first-order kinetics. 
C)  it will display second-order kinetics. 
D)  it will denature and cease to function.

Question 15

According to the steady-state assumption

Accepted Answer

A)  the product concentration does not change significantly 
B)  the substrate concentration is large and does not change significantly 
C)  the concentration of enzyme-substrate complex remains constant with time 
D)  the free enzyme concentration is always in great excess to the concentration of enzyme-substrate complex 
A)  the product concentration does not change significantly 
B)  the substrate concentration is large and does not change significantly 
C)  the concentration of enzyme-substrate complex remains constant with time 
D)  the free enzyme concentration is always in great excess to the concentration of enzyme-substrate complex

Question 16

The E-S complex often shows as a slight depression in the energy profile for the reaction.

Accepted Answer

A) True 
 B)False

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."Hindrate" is an inhibitor of triose phosphate isomerase.When it is added to cells at a concentration of 0.1 nM,the enzyme's KM for the substrate is unchanged,but the apparent Vmax is altered to 50 nM/sec.
In the following graph,which line best represents the Lineweaver-Burk plot obtained in the presence of hindrate?

Accepted Answer

A)  A 
B)  B 
C)  C 
D)  D 
E)  E 
A)  A 
B)  B 
C)  C 
D)  D 
E)  E

Question 18

Thermodynamically favorable reactions all release energy.

Accepted Answer

A) True 
 B)False

Question 19

The rate of a reaction depends on

Accepted Answer

A)  the free energy change 
B)  the activation energy 
C)  the enthalpy change 
D)  the entropy change 
A)  the free energy change 
B)  the activation energy 
C)  the enthalpy change 
D)  the entropy change

Question 20

The drug acetazolamide:

Accepted Answer

A)  Is used to help fight altitude sickness 
B)  Was found to ruin the taste of carbonated beverages 
C)  Does not affect the taste of non-carbonated liquors 
D)  Causes its effect on taste by inhibiting carbonic anhydrase 4 
E)  All of these 
A)  Is used to help fight altitude sickness 
B)  Was found to ruin the taste of carbonated beverages 
C)  Does not affect the taste of non-carbonated liquors 
D)  Causes its effect on taste by inhibiting carbonic anhydrase 4 
E)  All of these

Exam 6: The Behavior of Proteins: Enzymes

The steady state of an enzyme reaction is the following:

If an inhibitor changes the slope of the Lineweaver-Burk graph,but not the x-intercept,it is this type of inhibition:

Competitive inhibitors have this effect:

All catalysts work by lowering the activation energy for a reaction.

Non-competitive inhibitors have this effect:

The KM of hexokinase for glucose = 0.15 mM and for fructose,KM = 1.5 mM.Which is the preferred substrate?

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

If the y-intercept of a Lineweaver-Burk plot = 1.91 (sec/millimole) and the slope = 75.3 L/sec,KM equals:

The substrate will only bind to the enzyme when the shapes fit together rigidly.

A noncompetitive inhibitor

Most enzyme reactions display first order kinetics for the individual substrates when the substrate concentration is low.

When an enzyme is saturated with substrates,

According to the steady-state assumption

The E-S complex often shows as a slight depression in the energy profile for the reaction.

Thermodynamically favorable reactions all release energy.

The rate of a reaction depends on

The drug acetazolamide:

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 K_M of hexokinase for glucose = 0.15 mM and for fructose,K_M = 1.5 mM.Which is the preferred substrate?

If the y-intercept of a Lineweaver-Burk plot = 1.91 (sec/millimole) and the slope = 75.3 L/sec,K_M equals: