Question 1

In a comparison of allosteric and non-allosteric enzymes

Accepted Answer

A)  it is always possible to define a KM 
B)  it is always possible to define a Vmax 
C)  competitive inhibition is always a possibility 
D)  much of the terminology is completely unchanged 
A)  it is always possible to define a KM 
B)  it is always possible to define a Vmax 
C)  competitive inhibition is always a possibility 
D)  much of the terminology is completely unchanged

Question 2

Kinase reactions describe enzymes which

Accepted Answer

A)  add phosphate groups to another molecule. 
B)  oxidize alcohols to aldehydes. 
C)  use NAD+/NADH in their reactions. 
D)  transfer groups from one part of a molecule to another. 
E)  add or remove double bonds in molecules. 
A)  add phosphate groups to another molecule. 
B)  oxidize alcohols to aldehydes. 
C)  use NAD+/NADH in their reactions. 
D)  transfer groups from one part of a molecule to another. 
E)  add or remove double bonds in molecules.

Question 3

Inhibitors which bind covalently to specific amino acids are useful in determining which amino acids are in the active site of an enzyme.

Accepted Answer

A) True 
 B)False

Question 4

The sequential model for allosteric behavior

Accepted Answer

A)  cannot account for reactions that display negative cooperativity. 
B)  postulates binding of substrates and inhibitors by the induced-fit model. 
C)  requires that the conformation of all subunits change simultaneously. 
D)  is mathematically simpler than the concerted model. 
A)  cannot account for reactions that display negative cooperativity. 
B)  postulates binding of substrates and inhibitors by the induced-fit model. 
C)  requires that the conformation of all subunits change simultaneously. 
D)  is mathematically simpler than the concerted model.

Question 5

The initial bond formation in the covalent intermediate in the reaction catalyzed by chymotrypsin is between

Accepted Answer

A)  serine and the carbonyl carbon in the peptide backbone 
B)  serine and the nitrogen in the peptide backbone 
C)  histidine and the carbonyl carbon in the peptide backbone 
D)  histidine and the nitrogen in the peptide backbone 
A)  serine and the carbonyl carbon in the peptide backbone 
B)  serine and the nitrogen in the peptide backbone 
C)  histidine and the carbonyl carbon in the peptide backbone 
D)  histidine and the nitrogen in the peptide backbone

Question 6

Which of the following does not apply to the concerted model for subunit behavior:

Accepted Answer

A)  Each subunit can exist in a relaxed (R) and taut (T) conformation. 
B)  All subunits will be in either the R or the T conformation at the same time. 
C)  Some subunits can be in the R state while others are in the T state. 
D)  The presence of inhibitors will lead to more of the enzyme being in the T form 
E)  the presence of activators will lead to more of the enzyme being in the R form 
A)  Each subunit can exist in a relaxed (R) and taut (T) conformation. 
B)  All subunits will be in either the R or the T conformation at the same time. 
C)  Some subunits can be in the R state while others are in the T state. 
D)  The presence of inhibitors will lead to more of the enzyme being in the T form 
E)  the presence of activators will lead to more of the enzyme being in the R form

Question 7

A transition-state analog is likely to bind to an enzyme

Accepted Answer

A)  more tightly than the substrate. 
B)  less tightly than the substrate. 
C)  about as tightly as the substrate. 
D)  at a site other than the catalytic site. 
A)  more tightly than the substrate. 
B)  less tightly than the substrate. 
C)  about as tightly as the substrate. 
D)  at a site other than the catalytic site.

Question 8

Kinases usually transfer phosphates from

Accepted Answer

A)  ATP. 
B)  inorganic phosphate. 
C)  NADP+/NADPH. 
D)  amino acids. 
A)  ATP. 
B)  inorganic phosphate. 
C)  NADP+/NADPH. 
D)  amino acids.

Question 9

The sequential model for allosteric enzymes was proposed by:

Accepted Answer

A)  Koshland 
B)  Pauling 
C)  Pasteur 
D)  Monod, Wyman and Changeux 
E)  All of these 
A)  Koshland 
B)  Pauling 
C)  Pasteur 
D)  Monod, Wyman and Changeux 
E)  All of these

Question 10

Which of the following is unlikely to occur in binding of a substrate to an enzyme?

Accepted Answer

A)  stereospecific interactions. 
B)  hydrogen bonding. 
C)  adsorption to surfaces of metallic catalysts. 
D)  interactions with metal-ions. 
A)  stereospecific interactions. 
B)  hydrogen bonding. 
C)  adsorption to surfaces of metallic catalysts. 
D)  interactions with metal-ions.

Question 11

Which of the following can function as coenzymes?

Accepted Answer

A)  lead ion, biotin, and lipoic acid. 
B)  copper ion, p-hydroxymercuribenzoate, diisopropylphophofluoridate. 
C)  zinc ion, pyridoxal phosphate, and nicotinamide adenine nucleotides. 
D)  lead ion, p-hydroxymercuribenzoate, diisopropylphophofluoridate. 
A)  lead ion, biotin, and lipoic acid. 
B)  copper ion, p-hydroxymercuribenzoate, diisopropylphophofluoridate. 
C)  zinc ion, pyridoxal phosphate, and nicotinamide adenine nucleotides. 
D)  lead ion, p-hydroxymercuribenzoate, diisopropylphophofluoridate.

Question 12

What happens when a K-acting inhibitor is added to an allosteric enzyme system?

Accepted Answer

A)  The apparent KM for the substrate increases. 
B)  The apparent KM for the substrate decreases. 
C)  The apparent Vmax for the substrate increases. 
D)  The apparent Vmax for the substrate decreases. 
A)  The apparent KM for the substrate increases. 
B)  The apparent KM for the substrate decreases. 
C)  The apparent Vmax for the substrate increases. 
D)  The apparent Vmax for the substrate decreases.

Question 13

In the concerted model, which state binds the substrate more tightly?

Accepted Answer

A)  the relaxed (R) state 
B)  the taut (T) state 
C)  Both states bind equally well. 
A)  the relaxed (R) state 
B)  the taut (T) state 
C)  Both states bind equally well.

Question 14

How do each of these compounds affect the function of ATCase?

Accepted Answer

A)  ATP is a K effector and CTP is a V effector. 
B)  ATP is a V effector and CTP is a K effector. 
C)  Both ATP and CTP are K effectors. 
D)  Both ATP and CTP are V effectors. 
E)  none of these 
A)  ATP is a K effector and CTP is a V effector. 
B)  ATP is a V effector and CTP is a K effector. 
C)  Both ATP and CTP are K effectors. 
D)  Both ATP and CTP are V effectors. 
E)  none of these

Question 15

The serine in the active site of chymotrypsin functions as

Accepted Answer

A)  a Lewis acid. 
B)  a metal ion. 
C)  an electrophile. 
D)  a nucleophile. 
A)  a Lewis acid. 
B)  a metal ion. 
C)  an electrophile. 
D)  a nucleophile.

Question 16

Which of the following enzymes is not a serine protease?

Accepted Answer

A)  trypsin 
B)  chymotrypsin 
C)  thrombin 
D)  aspartyl transcarbamylase (ATCase) 
A)  trypsin 
B)  chymotrypsin 
C)  thrombin 
D)  aspartyl transcarbamylase (ATCase)

Question 17

In the concerted model for allosteric enzymes

Accepted Answer

A)  the relative affinities of substrate for the T and R conformations plays an important role in the cooperativity of the reaction. 
B)  the equilibrium between the T and R conformations plays a minor role. 
C)  the enzymatic activity of the T conformation is considerably higher than that of the R form. 
D)  it is possible to describe the reactions of all allosteric enzymes accurately. 
A)  the relative affinities of substrate for the T and R conformations plays an important role in the cooperativity of the reaction. 
B)  the equilibrium between the T and R conformations plays a minor role. 
C)  the enzymatic activity of the T conformation is considerably higher than that of the R form. 
D)  it is possible to describe the reactions of all allosteric enzymes accurately.

Question 18

$\text { Exhibit 7A }$

-Refer to Exhibit 7A. Which two enzymes would be the most likely ones to regulate if this pathway is dedicated to the formation of only one product?

Accepted Answer

A)  1 and 2 
B)  1 and 3 
C)  1 and 5 
D)  2 and 4 
E)  4 and 5 
A)  1 and 2 
B)  1 and 3 
C)  1 and 5 
D)  2 and 4 
E)  4 and 5

Question 19

The amino acids in the active site can be involved in all of these processes, except:

Accepted Answer

A)  Binding of the substrate. 
B)  Becoming part of the product of the reaction. 
C)  The actual chemical mechanism for the reaction. 
D)  Binding of some necessary cofactor for the reaction. 
E)  All of these can be functions of the amino acids in the active site 
A)  Binding of the substrate. 
B)  Becoming part of the product of the reaction. 
C)  The actual chemical mechanism for the reaction. 
D)  Binding of some necessary cofactor for the reaction. 
E)  All of these can be functions of the amino acids in the active site

Question 20

The vitamin pantothenic acid is involved in this type of reaction:

Accepted Answer

A)  Carboxylation reactions 
B)  Decarboxylation reactions 
C)  Redox reactions 
D)  Acyl transfer reactions 
E)  Transamination reactions 
A)  Carboxylation reactions 
B)  Decarboxylation reactions 
C)  Redox reactions 
D)  Acyl transfer reactions 
E)  Transamination reactions

Exam 7: The Behavior of Proteins: Enzymes, Mechanisms, and Control

In a comparison of allosteric and non-allosteric enzymes

Kinase reactions describe enzymes which

Inhibitors which bind covalently to specific amino acids are useful in determining which amino acids are in the active site of an enzyme.

The sequential model for allosteric behavior

The initial bond formation in the covalent intermediate in the reaction catalyzed by chymotrypsin is between

Which of the following does not apply to the concerted model for subunit behavior:

A transition-state analog is likely to bind to an enzyme

Kinases usually transfer phosphates from

The sequential model for allosteric enzymes was proposed by:

Which of the following is unlikely to occur in binding of a substrate to an enzyme?

Which of the following can function as coenzymes?

What happens when a K-acting inhibitor is added to an allosteric enzyme system?

In the concerted model, which state binds the substrate more tightly?

How do each of these compounds affect the function of ATCase?

The serine in the active site of chymotrypsin functions as

Which of the following enzymes is not a serine protease?

In the concerted model for allosteric enzymes

Exhibit 7A \text { Exhibit 7A } Exhibit 7A -Refer to Exhibit 7A. Which two enzymes would be the most likely ones to regulate if this pathway is dedicated to the formation of only one product?

The amino acids in the active site can be involved in all of these processes, except:

The vitamin pantothenic acid is involved in this type of reaction:

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

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

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