Question 1

In the concerted model the binding of the first substrate molecule will achieve all except

Accepted Answer

A)  facilitation of the binding of other substrate molecules. 
B)  facilitation of the conversion of other subunits to the active state. 
C)  facilitation of the binding of inhibitors to the enzyme. 
D)  All of these are facilitated by the binding of the first substrate molecule. 
E)  None of these answers is correct. 
A)  facilitation of the binding of other substrate molecules. 
B)  facilitation of the conversion of other subunits to the active state. 
C)  facilitation of the binding of inhibitors to the enzyme. 
D)  All of these are facilitated by the binding of the first substrate molecule. 
E)  None of these answers is correct. C

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. A

Question 3

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. A

Question 4

In the concerted model for allosteric enzymes, if the taut form of the enzyme cannot bind substrate then

Accepted Answer

A)  KT 
B)  L = R\T 
C)  c = 0 
D)  an inhibitor must be present 
E)  none of these 
A)  KT 
B)  L = R\T 
C)  c = 0 
D)  an inhibitor must be present 
E)  none of these

Question 5

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 6

Where do allosteric inhibitors bind on an enzyme?

Accepted Answer

A)  They always bind at a site different from the active site. 
B)  They always bind at the active site. 
C)  They can bind at either active site or another site. 
D)  They always bind directly to the substrate 
E)  none of these 
A)  They always bind at a site different from the active site. 
B)  They always bind at the active site. 
C)  They can bind at either active site or another site. 
D)  They always bind directly to the substrate 
E)  none of these

Question 7

The saturation curve for aspartyl transcarbamylase has a similar shape to the curve for:

Accepted Answer

A)  Myoglobin 
B)  Hemoglobin 
C)  Chymotrypsin 
D)  Both hemoglobin and chymotrypsin. 
E)  All of these. 
A)  Myoglobin 
B)  Hemoglobin 
C)  Chymotrypsin 
D)  Both hemoglobin and chymotrypsin. 
E)  All of these.

Question 8

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 9

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 10

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 11

Explain how an active site affects the specificity of enzymes.

Accepted Answer

The nature of the active site plays an i

Question 12

Generally speaking, enzymes involved in pathways which generate ATP will be activated by addition of phosphate groups to the enzyme.

Accepted Answer

A) True 
 B)False

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

Which of the following amino acid side chains would best serve as a general acid, assuming the protein functions at a pH of 7?

Accepted Answer

A)  alanine 
B)  aspartic acid 
C)  lysine 
D)  asparagine 
A)  alanine 
B)  aspartic acid 
C)  lysine 
D)  asparagine

Question 15

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.

Question 16

Which of the following is true?

Accepted Answer

A)  Phosphorylation always increases enzyme activity 
B)  Kinases often use AMP as a co-substrate in their phosphorylation reactions 
C)  Some enzymes are activated by phosphorylation while others are inhibited 
D)  ADP is the most common substrate for a kinase reaction 
A)  Phosphorylation always increases enzyme activity 
B)  Kinases often use AMP as a co-substrate in their phosphorylation reactions 
C)  Some enzymes are activated by phosphorylation while others are inhibited 
D)  ADP is the most common substrate for a kinase reaction

Question 17

Enzyme kinetics falls into two general categories, simple saturation and cooperative kinetics.

Accepted Answer

A) True 
 B)False

Question 18

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 19

Enzymes that catalyze similar functions will invariably have

Accepted Answer

A)  similar overall structures. 
B)  serine in their active sites. 
C)  histidine in their active sites. 
D)  active sites that can catalyze the reactions in question. 
A)  similar overall structures. 
B)  serine in their active sites. 
C)  histidine in their active sites. 
D)  active sites that can catalyze the reactions in question.

Question 20

Which of the following is true about salicylate?

Accepted Answer

A)  it is a natural compound from the bark of a tree 
B)  it is structurally similar to aspirin 
C)  it stimulates the protein kinase, AMPK 
D)  it has therapeutic effects in lowering the risk of heart disease 
E)  all of these 
A)  it is a natural compound from the bark of a tree 
B)  it is structurally similar to aspirin 
C)  it stimulates the protein kinase, AMPK 
D)  it has therapeutic effects in lowering the risk of heart disease 
E)  all of these

Exam 7: The Behavior of Proteins Enzymes Mechanisms and Control

In the concerted model the binding of the first substrate molecule will achieve all except

Kinase reactions describe enzymes which

Kinases usually transfer phosphates from

In the concerted model for allosteric enzymes, if the taut form of the enzyme cannot bind substrate then

In the concerted model for allosteric enzymes

Where do allosteric inhibitors bind on an enzyme?

The saturation curve for aspartyl transcarbamylase has a similar shape to the curve for:

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

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

Abzymes

Explain how an active site affects the specificity of enzymes.

Generally speaking, enzymes involved in pathways which generate ATP will be activated by addition of phosphate groups to the enzyme.

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

Which of the following amino acid side chains would best serve as a general acid, assuming the protein functions at a pH of 7?

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

Which of the following is true?

Enzyme kinetics falls into two general categories, simple saturation and cooperative kinetics.

Pyridoxal phosphate is required for transfer of

Enzymes that catalyze similar functions will invariably have

Which of the following is true about salicylate?

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