Question 1

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 C

Question 2

Thermodynamically favorable reactions all release energy.

Accepted Answer

A) True 
 B)False  True

Question 3

When the substrate concentration is low, an enzyme reaction

Accepted Answer

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

Question 4

The order of a reaction can be determined from the balanced equation for the reaction.

Accepted Answer

A) True 
 B)False

Question 5

What effect does a catalyst have on the ΔG° of a reaction?

Accepted Answer

A)  A catalyst lowers the ΔG°. 
B)  A catalyst raises the ΔG°. 
C)  A catalyst has no effect on the ΔG°. 
D)  It depend on the specific catalyst. 
A)  A catalyst lowers the ΔG°. 
B)  A catalyst raises the ΔG°. 
C)  A catalyst has no effect on the ΔG°. 
D)  It depend on the specific catalyst.

Question 6

The KM expression is equal to

Accepted Answer

A)  (k1 + k2) / k−1 
B)  (k−1 + k2) / k1 
C)  (k1 + k−1) / k2 
D)  k−1 / k1 
A)  (k1 + k2) / k−1 
B)  (k−1 + k2) / k1 
C)  (k1 + k−1) / k2 
D)  k−1 / k1

Question 7

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

$k_{1}=10^{8} \mathrm{M}^{-1} \mathrm{~s}^{-1}, k_{-1}=100 \mathrm{~s}^{-1}, k_{2}=900 \mathrm{~s}^{-1}$
-Refer to Exhibit 6A. What is the Vmax of the enzyme?

Accepted Answer

A)  90 nM/s 
B)  4500 µM/s 
C)  200 µM/s 
D)  0.5 M/s 
A)  90 nM/s 
B)  4500 µM/s 
C)  200 µM/s 
D)  0.5 M/s

Question 8

Which of the following statements regarding the Michaelis constant is false?

Accepted Answer

A)  It is similar to the affinity constant between the enzyme and substrate. 
B)  The dimension for the Michaelis constant is concentration, such as molarity. 
C)  The Michaelis constant determines the Vmax. 
D)  It is the substrate concentration necessary to reach 1/2 Vmax. 
A)  It is similar to the affinity constant between the enzyme and substrate. 
B)  The dimension for the Michaelis constant is concentration, such as molarity. 
C)  The Michaelis constant determines the Vmax. 
D)  It is the substrate concentration necessary to reach 1/2 Vmax.

Question 9

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 10

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

Accepted Answer

A) True 
 B)False

Question 11

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

$k_{1}=10^{8} \mathrm{M}^{-1} \mathrm{~s}^{-1}, k_{-1}=100 \mathrm{~s}^{-1}, k_{2}=900 \mathrm{~s}^{-1}$
-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 12

In the reaction catalyzed by aspartate transcarbamoylase, a graph in which the rate is plotted against the concentration of substrate

Accepted Answer

A)  is sigmoidal, characteristic of an allosteric enzyme 
B)  shows that noncooperative kinetics are observed 
C)  shows that the reaction is zero order 
D)  is hyperbolic, characteristic of a nonallosteric enzyme 
A)  is sigmoidal, characteristic of an allosteric enzyme 
B)  shows that noncooperative kinetics are observed 
C)  shows that the reaction is zero order 
D)  is hyperbolic, characteristic of a nonallosteric enzyme

Question 13

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 14

Which of the following inhibitors binds to the enzyme at a site other than the active site?

Accepted Answer

A)  competitive inhibitor 
B)  noncompetitive inhibitor 
C)  irreversible inhibitor 
D)  all of these 
E)  none of these 
A)  competitive inhibitor 
B)  noncompetitive inhibitor 
C)  irreversible inhibitor 
D)  all of these 
E)  none of these

Question 15

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 are correct 
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 are correct

Question 16

The substrate-enzyme (E-S) complex

Accepted Answer

A)  always proceeds to form the products rapidly. 
B)  always breaks down to form free enzyme and substrate. 
C)  always breaks down to form free enzyme and product. 
D)  may break down to form free enzyme and substrate, or free enzyme and product. 
A)  always proceeds to form the products rapidly. 
B)  always breaks down to form free enzyme and substrate. 
C)  always breaks down to form free enzyme and product. 
D)  may break down to form free enzyme and substrate, or free enzyme and product.

Question 17

When an enzyme-catalyzed reaction has two substrates and substrate A must bind before substrate B, the mechanism is called

Accepted Answer

A)  a ping-pong mechanism 
B)  a random mechanism 
C)  an ordered mechanism 
D)  a suicide mechanism 
E)  none of these is true 
A)  a ping-pong mechanism 
B)  a random mechanism 
C)  an ordered mechanism 
D)  a suicide mechanism 
E)  none of these is true

Question 18

In the reaction catalyzed by chymotrypsin, a graph in which the rate is plotted against the concentration of substrate

Accepted Answer

A)  is sigmoidal, characteristic of an allosteric enzyme 
B)  shows that cooperative kinetics are observed 
C)  shows that the reaction is zero order 
D)  is hyperbolic, characteristic of a nonallosteric enzyme 
A)  is sigmoidal, characteristic of an allosteric enzyme 
B)  shows that cooperative kinetics are observed 
C)  shows that the reaction is zero order 
D)  is hyperbolic, characteristic of a nonallosteric enzyme

Question 19

Which of the following is not related to the others?

Accepted Answer

A)  Suicide Substrate 
B)  Irreversible Inhibitor 
C)  Trojan Horse substrate 
D)  Competitive Inhibitor 
E)  All of these are related 
A)  Suicide Substrate 
B)  Irreversible Inhibitor 
C)  Trojan Horse substrate 
D)  Competitive Inhibitor 
E)  All of these are related

Question 20

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

Accepted Answer

A)  0.0254 millimoles per second. 
B)  0.523 millimoles per second. 
C)  5.23 millimoles per second. 
D)  39.4 millimoles per second. 
E)  75.3 millimoles per second. 
A)  0.0254 millimoles per second. 
B)  0.523 millimoles per second. 
C)  5.23 millimoles per second. 
D)  39.4 millimoles per second. 
E)  75.3 millimoles per second.

Exam 6: The Behavior of Proteins: Enzymes

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

Thermodynamically favorable reactions all release energy.

When the substrate concentration is low, an enzyme reaction

The order of a reaction can be determined from the balanced equation for the reaction.

What effect does a catalyst have on the ΔG° of a reaction?

The KM expression is equal to

Which of the following statements regarding the Michaelis constant is false?

The reaction catalyzed by aspartate transcarbamoylase is

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

In the reaction catalyzed by aspartate transcarbamoylase, a graph in which the rate is plotted against the concentration of substrate

Competitive inhibitors have this effect:

Which of the following inhibitors binds to the enzyme at a site other than the active site?

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

The substrate-enzyme (E-S) complex

When an enzyme-catalyzed reaction has two substrates and substrate A must bind before substrate B, the mechanism is called

In the reaction catalyzed by chymotrypsin, a graph in which the rate is plotted against the concentration of substrate

Which of the following is not related to the others?

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

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 expression is equal to

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