Question 1

Labeling the amino acid residues in the active site of an enzyme requires

Accepted Answer

A)  a reagent structurally similar to the substrate. 
B)  a highly polar reagent. 
C)  a reagent that contains an aromatic group. 
D)  a reagent that contains a halogen atom. 
A)  a reagent structurally similar to the substrate. 
B)  a highly polar reagent. 
C)  a reagent that contains an aromatic group. 
D)  a reagent that contains a halogen atom. A

Question 2

Exhibit 7A   Refer to Exhibit 7A.Which two enzymes would be the most likely ones to regulate if this pathway is freely reversible and can go both ways?

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 C

Question 3

Homotrophic effects for allosteric enzymes involve

Accepted Answer

A)  the same molecule binding to different sites in the enzyme. 
B)  different molecules binding to the same site in an enzyme. 
C)  different molecules binding to different sites in the same enzyme. 
D)  All of these are homotrophic effects. 
A)  the same molecule binding to different sites in the enzyme. 
B)  different molecules binding to the same site in an enzyme. 
C)  different molecules binding to different sites in the same enzyme. 
D)  All of these are homotrophic effects. A

Question 4

The pH profile of an enzyme can help identify specific amino acids in the active site because:

Accepted Answer

A)  all enzymes have a pH optimum 
B)  only the active site amino acids can detect changes in pH 
C)  acidic and basic amino acids are often involved in the active site and pH changes can change their ability to catalyze a reaction 
D)  the pH optimum is always the pI of the most critical amino acid in the active site 
A)  all enzymes have a pH optimum 
B)  only the active site amino acids can detect changes in pH 
C)  acidic and basic amino acids are often involved in the active site and pH changes can change their ability to catalyze a reaction 
D)  the pH optimum is always the pI of the most critical amino acid in the active site

Question 5

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 6

B vitamins are often stored in the body.

Accepted Answer

A) True 
 B)False

Question 7

Abzymes

Accepted Answer

A)  invariably bind to pyridoxal phosphate. 
B)  are antibodies with catalytic activity. 
C)  differ markedly from transition states in enzymatic reactions. 
D)  have proline as part of their structure. 
A)  invariably bind to pyridoxal phosphate. 
B)  are antibodies with catalytic activity. 
C)  differ markedly from transition states in enzymatic reactions. 
D)  have proline as part of their structure.

Question 8

Important mechanisms of enzymatic catalysis include

Accepted Answer

A)  nucleophilic reactions 
B)  general acid-base catalysis 
C)  Lewis acid-base catalysis 
D)  all of these 
A)  nucleophilic reactions 
B)  general acid-base catalysis 
C)  Lewis acid-base catalysis 
D)  all of these

Question 9

In zymogen activation

Accepted Answer

A)  only digestive enzymes are involved. 
B)  a conformational change takes place with no alteration of primary structure. 
C)  an inactive protein is converted to an active one by bond cleavage. 
D)  there is aggregation of several enzyme molecules when the substrate binds. 
A)  only digestive enzymes are involved. 
B)  a conformational change takes place with no alteration of primary structure. 
C)  an inactive protein is converted to an active one by bond cleavage. 
D)  there is aggregation of several enzyme molecules when the substrate binds.

Question 10

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 V effector and CTP K effector. 
C)  Both ATP and CTP are K effectors. 
D)  Both ATP and CTP are V effectors. 
A)  ATP is a K effector and CTP is a V effector. 
B)  ATP V effector and CTP K effector. 
C)  Both ATP and CTP are K effectors. 
D)  Both ATP and CTP are V effectors.

Question 11

Which of the following is true?

Accepted Answer

A)  Caspases are a class of proteases 
B)  Caspases are involved in apoptosis 
C)  Caspases are initially produced as inactive procaspases 
D)  all of these 
A)  Caspases are a class of proteases 
B)  Caspases are involved in apoptosis 
C)  Caspases are initially produced as inactive procaspases 
D)  all of these

Question 12

The term K0.5 is analogous to the KM

Accepted Answer

A) True 
 B)False

Question 13

The concerted model for allosteric behavior 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 14

ATP is a negative allosteric effector for glycogen phosporylase.This is an example of

Accepted Answer

A)  feedback inhibition. 
B)  positive cooperativity. 
C)  negative cooperativity. 
D)  competitive inhibition. 
A)  feedback inhibition. 
B)  positive cooperativity. 
C)  negative cooperativity. 
D)  competitive inhibition.

Question 15

Pyridoxal phosphate is required for transfer of

Accepted Answer

A)  one-carbon groups 
B)  amino groups 
C)  acyl groups 
D)  aldehyde groups 
A)  one-carbon groups 
B)  amino groups 
C)  acyl groups 
D)  aldehyde groups

Question 16

A velocity curve (V vs.[S]) for a typical allosteric enzyme will be

Accepted Answer

A)  a rectangular hyperbola. 
B)  a sigmoid curve. 
C)  a straight line. 
D)  a parabola. 
A)  a rectangular hyperbola. 
B)  a sigmoid curve. 
C)  a straight line. 
D)  a parabola.

Question 17

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 18

Which of the following is not required in order for an enzyme to display cooperative kinetics?

Accepted Answer

A)  Multiple subunits. 
B)  A value for the Michaelis constant, KM. 
C)  Allosteric sites which affect the binding of substrate to the active site. 
D)  Ability to display a Vmax. 
E)  All of these are characteristic of cooperative enzymes. 
A)  Multiple subunits. 
B)  A value for the Michaelis constant, KM. 
C)  Allosteric sites which affect the binding of substrate to the active site. 
D)  Ability to display a Vmax. 
E)  All of these are characteristic of cooperative enzymes.

Question 19

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 20

According to the concerted model of allosteric behavior,an allosteric activator

Accepted Answer

A)  favors the taut (tight) form of the enzyme. 
B)  favors the relaxed form of the enzyme. 
C)  can only bind to the enzyme if the substrate is already bound. 
D)  can only bind to the enzyme if the substrate has not already bound. 
A)  favors the taut (tight) form of the enzyme. 
B)  favors the relaxed form of the enzyme. 
C)  can only bind to the enzyme if the substrate is already bound. 
D)  can only bind to the enzyme if the substrate has not already bound.

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

Labeling the amino acid residues in the active site of an enzyme requires

Exhibit 7A Refer to Exhibit 7A.Which two enzymes would be the most likely ones to regulate if this pathway is freely reversible and can go both ways?

Homotrophic effects for allosteric enzymes involve

The pH profile of an enzyme can help identify specific amino acids in the active site because:

The vitamin biotin is involved in this type of reaction:

B vitamins are often stored in the body.

Abzymes

Important mechanisms of enzymatic catalysis include

In zymogen activation

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

Which of the following is true?

The term K0.5 is analogous to the KM

The concerted model for allosteric behavior was proposed by:

ATP is a negative allosteric effector for glycogen phosporylase.This is an example of

Pyridoxal phosphate is required for transfer of

A velocity curve (V vs.[S]) for a typical allosteric enzyme will be

Which of the following can function as coenzymes?

Which of the following is not required in order for an enzyme to display cooperative kinetics?

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

According to the concerted model of allosteric behavior,an allosteric activator

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

Filters

The term K_0.5 is analogous to the K_M