Question 1

The induced- fit model

Accepted Answer

A) proposes that very strong covalent bonds are formed upon substrate binding. 
B) is also called the lock- and- key model. 
C) was proposed by Hans Buchner. 
D) states that substrate- enzyme interactions are rigid. 
E) involves a conformational change in the shape of the enzyme. 
A) proposes that very strong covalent bonds are formed upon substrate binding. 
B) is also called the lock- and- key model. 
C) was proposed by Hans Buchner. 
D) states that substrate- enzyme interactions are rigid. 
E) involves a conformational change in the shape of the enzyme. E

Question 2

The site on an enzyme that is designed for the substrate to bind is called the _.

Accepted Answer

active site

Question 3

Of the following, which is used in the treatment of many bacterial and viral diseases to inhibit specific enzymes?

Accepted Answer

A) substrate analogs 
B) nitrous oxide 
C) noncompetitive inhibitors 
D) intercalating agents 
E) X- rays 
A) substrate analogs 
B) nitrous oxide 
C) noncompetitive inhibitors 
D) intercalating agents 
E) X- rays A

Question 4

Which of the following is an example of a prosthetic group?

Accepted Answer

A) a glycine residue 
B) a polypeptide chain 
C) carboxypeptidase A 
D) a zinc ion 
E) a nickel catalyst 
A) a glycine residue 
B) a polypeptide chain 
C) carboxypeptidase A 
D) a zinc ion 
E) a nickel catalyst

Question 5

Which of the following is an enzyme?

Accepted Answer

A) carboxypeptidase A 
B) iron 
C) histidine 
D) ATP 
E) N- acetylmuramic acid 
A) carboxypeptidase A 
B) iron 
C) histidine 
D) ATP 
E) N- acetylmuramic acid

Question 6

The equation AB + H2O -A + B would be catalyzed by which of the following classes of enzymes?

Accepted Answer

A) hydrolases 
B) oxidoreductases 
C) ligases 
D) isomerases 
E) transferases 
A) hydrolases 
B) oxidoreductases 
C) ligases 
D) isomerases 
E) transferases

Question 7

The Michaelis constant

Accepted Answer

A) can be determined using the Lineweaver- Burk plot. 
B) is equal to twice the Vmax. 
C) is equal to the substrate concentration at Vmax/2. 
D) choices A, B, and C 
E) both A and C 
A) can be determined using the Lineweaver- Burk plot. 
B) is equal to twice the Vmax. 
C) is equal to the substrate concentration at Vmax/2. 
D) choices A, B, and C 
E) both A and C

Question 8

Saturation can be defined as

Accepted Answer

A) denaturation of an enzyme. 
B) inhibition of enzyme function by blocking the active site. 
C) the substrate concentration at which velocity reaches one- half maximum velocity. 
D) the inability to increase reaction velocity beyond a finite upper limit. 
E) a characteristic of all uncatalyzed reactions. 
A) denaturation of an enzyme. 
B) inhibition of enzyme function by blocking the active site. 
C) the substrate concentration at which velocity reaches one- half maximum velocity. 
D) the inability to increase reaction velocity beyond a finite upper limit. 
E) a characteristic of all uncatalyzed reactions.

Question 9

The work of James B. Sumner was to

Accepted Answer

A) crystallize urease, the first enzyme isolated. 
B) originate the term ferments to describe enzymes. 
C) isolate the insulin hormone. 
D) prove that enzymes were carbohydrates. 
E) discover ribozymes. 
A) crystallize urease, the first enzyme isolated. 
B) originate the term ferments to describe enzymes. 
C) isolate the insulin hormone. 
D) prove that enzymes were carbohydrates. 
E) discover ribozymes.

Question 10

The site on an enzyme that will bind the substrate is called the

Accepted Answer

A) activation site. 
B) metastable site. 
C) active site. 
D) catalyst. 
E) prosthetic group. 
A) activation site. 
B) metastable site. 
C) active site. 
D) catalyst. 
E) prosthetic group.

Question 11

An enzyme is active in the stomach of an animal, but quickly loses its activity when it leaves the stomach. This example illustrates that enzymes are

Accepted Answer

A) specific to the organs in which they are produced. 
B) inactivated by inhibitors in the small intestine. 
C) sensitive to changes in pH. 
D) inactivated by movement. 
E) consumed by the quantities of substrate in the small intestine. 
A) specific to the organs in which they are produced. 
B) inactivated by inhibitors in the small intestine. 
C) sensitive to changes in pH. 
D) inactivated by movement. 
E) consumed by the quantities of substrate in the small intestine.

Question 12

An enzyme

Accepted Answer

A) binds substrates in a manner that facilitates the formation of product. 
B) does not change the rate at which the equilibrium is achieved. 
C) is always a protein. 
D) decreases the rate of a reaction. 
E) changes the position of the equilibrium of the reaction. 
A) binds substrates in a manner that facilitates the formation of product. 
B) does not change the rate at which the equilibrium is achieved. 
C) is always a protein. 
D) decreases the rate of a reaction. 
E) changes the position of the equilibrium of the reaction.

Question 13

A competitive inhibitor

Accepted Answer

A) binds at a site other than the active site. 
B) does not inhibit enzyme activity, but lowers substrate concentration. 
C) irreversibly binds and inactivates the enzyme. 
D) binds to and inactivates the substrate. 
E) cannot be processed by the enzyme. 
A) binds at a site other than the active site. 
B) does not inhibit enzyme activity, but lowers substrate concentration. 
C) irreversibly binds and inactivates the enzyme. 
D) binds to and inactivates the substrate. 
E) cannot be processed by the enzyme.

Question 14

As new enzymes are discovered, the EC system for naming enzymes is to be used. The names are to be based on which of the following criteria?

Accepted Answer

A) the six major classes of enzyme function 
B) the size of the enzyme 
C) the name of the substrate 
D) an indication of the size of the substrate 
E) a description of substrate function 
A) the six major classes of enzyme function 
B) the size of the enzyme 
C) the name of the substrate 
D) an indication of the size of the substrate 
E) a description of substrate function

Question 15

The Eadie- Hofstee plot

Accepted Answer

A) has the y intercept as Vmax. 
B) has the x axis as substrate concentration. 
C) slope can be used to determine Km. 
D) has the y axis as v/[S]. 
E) both C and D 
A) has the y intercept as Vmax. 
B) has the x axis as substrate concentration. 
C) slope can be used to determine Km. 
D) has the y axis as v/[S]. 
E) both C and D

Question 16

Enzyme regulation may occur by several methods. Which of the following is NOT a means of enzyme regulation?

Accepted Answer

A) allosteric regulation 
B) substrate- level phosphorylation 
C) saturation 
D) feedback inhibition 
E) covalent modification 
A) allosteric regulation 
B) substrate- level phosphorylation 
C) saturation 
D) feedback inhibition 
E) covalent modification

Question 17

inhibitors bind reversibly at the active site of an enzyme.

Accepted Answer

The answer of inhibitors bind reversibly at the active site...

Question 18

Which of the following best describes a metastable state?

Accepted Answer

A) This state is composed of the difference in activation energy of a catalyzed versus an uncatalyzed reaction. 
B) This state changes the position of the equilibrium, but not the rate. 
C) The metastable state is formed by transient complexes with the substrate. 
D) The metastable state is created by the prosthetic group of the enzyme. 
E) The metastable state is a state of the substrate in which the reaction can proceed, but usually will not proceed, without a catalyst. 
A) This state is composed of the difference in activation energy of a catalyzed versus an uncatalyzed reaction. 
B) This state changes the position of the equilibrium, but not the rate. 
C) The metastable state is formed by transient complexes with the substrate. 
D) The metastable state is created by the prosthetic group of the enzyme. 
E) The metastable state is a state of the substrate in which the reaction can proceed, but usually will not proceed, without a catalyst.

Question 19

Covalent modification

Accepted Answer

A) produces modifications that can sometimes be reversed. 
B) affects the activity of an enzyme by adding or removing a chemical group. 
C) can involve the addition of phosphate groups. 
D) can activate an enzyme. 
E) all of the above 
A) produces modifications that can sometimes be reversed. 
B) affects the activity of an enzyme by adding or removing a chemical group. 
C) can involve the addition of phosphate groups. 
D) can activate an enzyme. 
E) all of the above

Question 20

Which of the following does NOT accurately describe the Lineweaver- Burk plot?

Accepted Answer

A) The y intercept is equal to 1/Vmax. 
B) It is a linear plot. 
C) The x intercept is - 1/Km. 
D) Its slope is the same as the Eadie- Hofstee plot. 
E) It is a double reciprocal plot. 
A) The y intercept is equal to 1/Vmax. 
B) It is a linear plot. 
C) The x intercept is - 1/Km. 
D) Its slope is the same as the Eadie- Hofstee plot. 
E) It is a double reciprocal plot.

Exam 6: Enzymes: The Catalysts of Life

The induced- fit model

The site on an enzyme that is designed for the substrate to bind is called the _.

Of the following, which is used in the treatment of many bacterial and viral diseases to inhibit specific enzymes?

Which of the following is an example of a prosthetic group?

Which of the following is an enzyme?

The equation AB + H2O -A + B would be catalyzed by which of the following classes of enzymes?

The Michaelis constant

Saturation can be defined as

The work of James B. Sumner was to

The site on an enzyme that will bind the substrate is called the

An enzyme is active in the stomach of an animal, but quickly loses its activity when it leaves the stomach. This example illustrates that enzymes are

An enzyme

A competitive inhibitor

As new enzymes are discovered, the EC system for naming enzymes is to be used. The names are to be based on which of the following criteria?

The Eadie- Hofstee plot

Enzyme regulation may occur by several methods. Which of the following is NOT a means of enzyme regulation?

inhibitors bind reversibly at the active site of an enzyme.

Which of the following best describes a metastable state?

Covalent modification

Which of the following does NOT accurately describe the Lineweaver- Burk plot?

A Preview of the Cell

The Chemistry of the Cell

The Macromolecules of the Cell

Cells and Organelles

Bioenergetics: The Flow of Energy in the Cell

Membranes: Their Structure, Function, and Chemistry

Transport Across Membranes: Overcoming the Permeability Barrier

Chemotrophic Energy Metabolism: Glycolysis and Fermentation

Chemotrophic Energy Metabolism: Aerobic Respiration

Phototrophic Energy Metabolism: Photosynthesis

The Endomembrane System and Peroxisomes

Signal Transduction Mechanisms: I Electrical and Synaptic Signaling in Neurons

Signal Transduction Mechanisms: Ii Messengers and Receptors

Cytoskeletal Systems

Cellular Movement: Motility and Contractility

Beyond the Cell: Cell Adhesion, Cell Junctions, and Extracellular Structures

The Structural Basis of Cellular Information: DNA, Chromosomes, and the Nucleus

The Cell Cycle, Dna Replication, and Mitosis

Sexual Reproduction, Meiosis, and Genetic Recombination

Gene Expression: I the Genetic Code and Transcription

Gene Expression: II Protein Synthesis and Sorting

The Regulation of Gene Expression

Cancer Cells

Filters