Question 1

The binding of aspartate to different subunits of ATCase is an example of

Accepted Answer

A)  enzyme inhibition 
B)  a heterotropic effect 
C)  a homotropic effect 
D)  negative cooperativity 
E)  none of these 
A)  enzyme inhibition 
B)  a heterotropic effect 
C)  a homotropic effect 
D)  negative cooperativity 
E)  none of these

Question 2

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 3

The critical serine residue in the active site of chymotrypsin functions as

Accepted Answer

A)  a nucleophile. 
B)  an electrophile. 
C)  a base. 
D)  a methyl donor. 
E)  none of these 
A)  a nucleophile. 
B)  an electrophile. 
C)  a base. 
D)  a methyl donor. 
E)  none of these

Question 4

Nicotinamide adenine dinucleotide is

Accepted Answer

A)  an enzyme inhibitor used in smoking cessation programs. 
B)  an inhibitor of ATP production. 
C)  a coenzyme in reactions that transfer acyl groups. 
D)  a coenzyme in oxidation-reduction reactions. 
A)  an enzyme inhibitor used in smoking cessation programs. 
B)  an inhibitor of ATP production. 
C)  a coenzyme in reactions that transfer acyl groups. 
D)  a coenzyme in oxidation-reduction reactions.

Question 5

An important step in elucidating the behavior of an enzyme is

Accepted Answer

A)  obtaining a crystalline sample of the enzyme. 
B)  insuring that metal ions are always excluded from the enzyme sample. 
C)  determining the active site residues. 
D)  none of these 
A)  obtaining a crystalline sample of the enzyme. 
B)  insuring that metal ions are always excluded from the enzyme sample. 
C)  determining the active site residues. 
D)  none of these

Question 6

The term K0.5 is analogous to the KM

Accepted Answer

A) True 
 B)False

Question 7

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 8

How do K systems and V systems of enzymes differ from each other?

Accepted Answer

There are two types of enzyme systems, c

Question 9

The main distinguishing feature of the concerted model for the behavior of allosteric enzymes is that

Accepted Answer

A)  the conformation of all subunits changes simultaneously. 
B)  it applies only to dimeric enzymes. 
C)  it involves three possible conformations for all subunits. 
D)  the T and R conformations exist in roughly equal amounts. 
A)  the conformation of all subunits changes simultaneously. 
B)  it applies only to dimeric enzymes. 
C)  it involves three possible conformations for all subunits. 
D)  the T and R conformations exist in roughly equal amounts.

Question 10

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 11

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 12

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 13

B vitamins are often stored in the body.

Accepted Answer

A) True 
 B)False

Question 14

The vitamin biotin 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

Question 15

CTP is a known inhibitor of ATCase, the enzyme that catalyzes the first reaction in the pathway for the synthesis of this compound. This is an example of

Accepted Answer

A)  irreversible inhibition 
B)  feedback inhibition 
C)  zymogenic inhibition 
D)  negative cooperativity 
A)  irreversible inhibition 
B)  feedback inhibition 
C)  zymogenic inhibition 
D)  negative cooperativity

Question 16

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 17

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 18

In the concerted model the most active enzyme form will be when

Accepted Answer

A)  all subunits are in the R state. 
B)  all subunits are in the T state. 
C)  there is a 50:50 mix of R & T states. 
D)  none of these 
A)  all subunits are in the R state. 
B)  all subunits are in the T state. 
C)  there is a 50:50 mix of R & T states. 
D)  none of these

Question 19

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 20

​ The process by which the final product of a series of reactions inhibits the first reaction in the series is called _____.

Accepted Answer

A)  competitive inhibition 
B)  feedback inhibition 
C)  mixed inhibition 
D)  slow-tight inhibition 
A)  competitive inhibition 
B)  feedback inhibition 
C)  mixed inhibition 
D)  slow-tight inhibition

Exam 7: The Behavior of Proteins Enzymes Mechanisms and Control

The binding of aspartate to different subunits of ATCase is an example of

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

The critical serine residue in the active site of chymotrypsin functions as

Nicotinamide adenine dinucleotide is

An important step in elucidating the behavior of an enzyme is

The term K0.5 is analogous to the KM

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?

How do K systems and V systems of enzymes differ from each other?

The main distinguishing feature of the concerted model for the behavior of allosteric enzymes is that

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

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

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

B vitamins are often stored in the body.

The vitamin biotin is involved in this type of reaction:

CTP is a known inhibitor of ATCase, the enzyme that catalyzes the first reaction in the pathway for the synthesis of this compound. This is an example of

The sequential model for allosteric behavior

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

In the concerted model the most active enzyme form will be when

Which of the following can function as coenzymes?

​ The process by which the final product of a series of reactions inhibits the first reaction in the series is called _____.

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 the 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 term K_0.5 is analogous to the K_M

The process by which the final product of a series of reactions inhibits the first reaction in the series is called _____.