Question 1

Of the following types of molecular interactions, which is NOT likely to be involved in the binding of an enzyme to a substrate?

Accepted Answer

A) covalent linkages 
B) hydrogen bonds 
C) van der Waals attractions 
D) polar-polar attractions 
E) ionic attractions 
A) covalent linkages 
B) hydrogen bonds 
C) van der Waals attractions 
D) polar-polar attractions 
E) ionic attractions A

Question 2

Which class of enzymes catalyzes reactions involving the formation of double bonds?

Accepted Answer

A) elastases 
B) oxidoreductases 
C) lyases 
D) catalases 
E) isomerases 
A) elastases 
B) oxidoreductases 
C) lyases 
D) catalases 
E) isomerases C

Question 3

Which of the following best describes the type of binding between an irreversible inhibitor and an enzyme?

Accepted Answer

A) weak 
B) non-covalent 
C) hydrogen bonding 
D) hydrophobic interactions 
E) very tight 
A) weak 
B) non-covalent 
C) hydrogen bonding 
D) hydrophobic interactions 
E) very tight E

Question 4

Phenylketonuria (PKU) is an inherited disease caused by the inability to produce a properly working form of the enzyme phenylalanine hydroxylase.This enzyme catalyzes the conversion of the amino acid phenylalanine to the amino acid tyrosine by adding a hydroxyl group to the para position on the ring.Based on this information, what is the structure of tyrosine (Tyr)?

Accepted Answer

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

Question 5

Some enzymes require an additional nonprotein prosthetic group in order to function.What is the protein part of this combination called?

Accepted Answer

A) substrate 
B) apoenzyme 
C) effector 
D) cofactor 
E) holoenzyme 
A) substrate 
B) apoenzyme 
C) effector 
D) cofactor 
E) holoenzyme

Question 6

Binding of a negative effector converts an active site on an enzyme into the active configuration.

Accepted Answer

A) True 
 B)False

Question 7

What is the term for a molecule that is similar in structure and charge distribution to the substrate in an enzyme-catalyzed reaction?

Accepted Answer

A) effector 
B) transition state 
C) structural analog 
D) irreversible inhibitor 
E) noncompetitive inhibitor 
A) effector 
B) transition state 
C) structural analog 
D) irreversible inhibitor 
E) noncompetitive inhibitor

Question 8

What three structurally similar pancreatic serine proteases function to cleave certain peptide bonds in proteins?

Accepted Answer

A) pepsinogen, zymogen, and acetylcholinesterase 
B) pepsinogen, trypsin, and pepsin 
C) tryptophan, trypsin, and chymotrypsin 
D) trypsin, chymotrypsin, and elastase 
E) choline, tryptophan, and proline 
A) pepsinogen, zymogen, and acetylcholinesterase 
B) pepsinogen, trypsin, and pepsin 
C) tryptophan, trypsin, and chymotrypsin 
D) trypsin, chymotrypsin, and elastase 
E) choline, tryptophan, and proline

Question 9

Carboxypetidase A is a highly folded, globular protein that functions as a protease enzyme.Which of the following is a likely assumption about the amino acid residues that exist on the exterior of this folded protein?

Accepted Answer

A) The majority of these amino acids have disulfide bonds between cysteine residues. 
B) The majority of these amino acids are hydrophilic in nature. 
C) The majority of these residues are glycine. 
D) None of these residues is serine. 
E) The majority of these residues are nonpolar in nature. 
A) The majority of these amino acids have disulfide bonds between cysteine residues. 
B) The majority of these amino acids are hydrophilic in nature. 
C) The majority of these residues are glycine. 
D) None of these residues is serine. 
E) The majority of these residues are nonpolar in nature.

Question 10

What type of enzyme regulation occurs when the final product of a pathway shuts off the entire pathway for its own synthesis?

Accepted Answer

A) irreversible inhibition 
B) competitive inhibition 
C) feedback inhibition 
D) poisoning 
E) noncompetitive inhibition 
A) irreversible inhibition 
B) competitive inhibition 
C) feedback inhibition 
D) poisoning 
E) noncompetitive inhibition

Question 11

What portion of an enzyme is in direct contact with the substrate?

Accepted Answer

A) the inert site 
B) the alpha site 
C) the beta site 
D) the delta site 
E) the active site 
A) the inert site 
B) the alpha site 
C) the beta site 
D) the delta site 
E) the active site

Question 12

Sucrase is an example of an enzyme that displays absolute specificity.What does the term "absolute specificity" indicate about an enzyme?

Accepted Answer

A) It catalyzes the reaction of only a single substrate. 
B) It catalyzes the reaction of only one class of compounds. 
C) It catalyzes one type of reaction for the same class of compounds. 
D) It catalyzes the reaction of only a single enantiomer of a compound. 
E) It catalyzes the reaction of only a single type of bond. 
A) It catalyzes the reaction of only a single substrate. 
B) It catalyzes the reaction of only one class of compounds. 
C) It catalyzes one type of reaction for the same class of compounds. 
D) It catalyzes the reaction of only a single enantiomer of a compound. 
E) It catalyzes the reaction of only a single type of bond.

Question 13

What parameter of a reaction does an enzyme alter?

Accepted Answer

A) product structure 
B) activation energy 
C) pH 
D) temperature 
E) concentration 
A) product structure 
B) activation energy 
C) pH 
D) temperature 
E) concentration

Question 14

The rate of an enzyme-catalyzed reaction initially increases with an increase in the substrate concentration, but eventually reaches a maximum value, even though the concentration of substrate continues to increase.Which of the following best explains why?

Accepted Answer

A) As substrate concentration increases, the substrates preferentially bind with each other instead of the active site of the enzyme, and no additional catalysis occurs. 
B) As substrate concentration increases, the active sites of all the enzyme molecules become occupied with substrate molecules, and no additional binding can occur. 
C) An increase in substrate concentration eventually increases the temperature of the reaction mixture, and the enzyme becomes denatured. 
D) An increase in substrate concentration allows for greater competition between substrate and inhibitor binding, and enzyme activity ceases. 
E) When substrate concentrations become too high, local variations of pH occur that cause the enzyme to become denatured. 
A) As substrate concentration increases, the substrates preferentially bind with each other instead of the active site of the enzyme, and no additional catalysis occurs. 
B) As substrate concentration increases, the active sites of all the enzyme molecules become occupied with substrate molecules, and no additional binding can occur. 
C) An increase in substrate concentration eventually increases the temperature of the reaction mixture, and the enzyme becomes denatured. 
D) An increase in substrate concentration allows for greater competition between substrate and inhibitor binding, and enzyme activity ceases. 
E) When substrate concentrations become too high, local variations of pH occur that cause the enzyme to become denatured.

Question 15

Chymotrypsin catalyzes the hydrolysis of dietary carbohydrates.

Accepted Answer

A) True 
 B)False

Question 16

Which of the following correctly describes pepsinogen?

Accepted Answer

A) It is the inactive form of the enzyme pepsin. 
B) It is the cofactor for the enzyme pepsin. 
C) It is the inhibitor of the enzyme pepsin. 
D) It is an isoenzyme of pepsin. 
E) It is the name of the reaction catalyzed by pepsin. 
A) It is the inactive form of the enzyme pepsin. 
B) It is the cofactor for the enzyme pepsin. 
C) It is the inhibitor of the enzyme pepsin. 
D) It is an isoenzyme of pepsin. 
E) It is the name of the reaction catalyzed by pepsin.

Question 17

Hydrochloric acid in the stomach is partially responsible for activating pepsinogen.

Accepted Answer

A) True 
 B)False

Question 18

What is the effect of an enzyme on the equilibrium constant for the reaction it catalyzes?

Accepted Answer

A) It increases the equilibrium constant. 
B) It decreases the equilibrium constant. 
C) It may increase or decrease the equilibrium constant, depending upon the specific reaction. 
D) It makes the equilibrium constant numerically equal to the reaction rate. 
E) It has no effect on the equilibrium constant. 
A) It increases the equilibrium constant. 
B) It decreases the equilibrium constant. 
C) It may increase or decrease the equilibrium constant, depending upon the specific reaction. 
D) It makes the equilibrium constant numerically equal to the reaction rate. 
E) It has no effect on the equilibrium constant.

Question 19

Trypsin is a protease enzyme that cleaves peptide bonds on the carbonyl side of basic amino acids.Which labeled bond(s) in the peptide below would be cleaved by trypsin?

Accepted Answer

A) A 
B) B 
C) C 
D) D 
E) A, C, and D 
A) A 
B) B 
C) C 
D) D 
E) A, C, and D

Question 20

The rates of enzyme-catalyzed reactions increase with increasing pH.

Accepted Answer

A) True 
 B)False

Exam 19: Enzymes

Of the following types of molecular interactions, which is NOT likely to be involved in the binding of an enzyme to a substrate?

Which class of enzymes catalyzes reactions involving the formation of double bonds?

Which of the following best describes the type of binding between an irreversible inhibitor and an enzyme?

Some enzymes require an additional nonprotein prosthetic group in order to function.What is the protein part of this combination called?

Binding of a negative effector converts an active site on an enzyme into the active configuration.

What is the term for a molecule that is similar in structure and charge distribution to the substrate in an enzyme-catalyzed reaction?

What three structurally similar pancreatic serine proteases function to cleave certain peptide bonds in proteins?

Carboxypetidase A is a highly folded, globular protein that functions as a protease enzyme.Which of the following is a likely assumption about the amino acid residues that exist on the exterior of this folded protein?

What type of enzyme regulation occurs when the final product of a pathway shuts off the entire pathway for its own synthesis?

What portion of an enzyme is in direct contact with the substrate?

Sucrase is an example of an enzyme that displays absolute specificity.What does the term "absolute specificity" indicate about an enzyme?

What parameter of a reaction does an enzyme alter?

The rate of an enzyme-catalyzed reaction initially increases with an increase in the substrate concentration, but eventually reaches a maximum value, even though the concentration of substrate continues to increase.Which of the following best explains why?

Chymotrypsin catalyzes the hydrolysis of dietary carbohydrates.

Which of the following correctly describes pepsinogen?

Hydrochloric acid in the stomach is partially responsible for activating pepsinogen.

What is the effect of an enzyme on the equilibrium constant for the reaction it catalyzes?

Trypsin is a protease enzyme that cleaves peptide bonds on the carbonyl side of basic amino acids.Which labeled bond(s) in the peptide below would be cleaved by trypsin?

The rates of enzyme-catalyzed reactions increase with increasing pH.

Chemistry:methods and Measurement

The Structure of the Atom and the Periodic Table

Structure and Properties of Ionic and Covalent Compounds

Calculations, Chemical Changes, and the Chemical Equation

States of Matter- Gases, Liquids, and Solids

Solutions

Energy, Rate and Equilibrium

Acids and Bases

The Nucleus, Radioactivity, and Nuclear Medicine

An Introduction to Organic Chemistry- the Saturated Hydrocarbons

The Unsaturated Hydrocarbons- Alkenes, Alkynes, and Aromatics

Alcohols, Phenols, Thiols, and Ethers

Aldehydes and Ketones

Carboxylic Acids and Carboxylic Acid Derivatives

Amines and Amides

Carbohydrates

Lipids and Their Functions in Biochemical Systems

Protein Structure and Function

Introduction to Molecular Genetics

Carbohydrate Metabolism

Aerobic Respiration and Energy Production

Fatty Acid Metabolism

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