Question 1

The time that is required for an enzyme to convert one substrate molecule into one product molecule is

Accepted Answer

A)  Km.  
B)  kcat.  
C)  1/Km.  
D)  1/kcat. 
A)  Km.  
B)  kcat.  
C)  1/Km.  
D)  1/kcat.

Question 2

The main difference between chemical and enzyme kinetics is that

Accepted Answer

A)  enzyme reactions are altered by pH. 
B)  enzyme reactions depend on the concentration of the substrate. 
C)  enzyme reactions depend on the concentration of the enzyme and its recycling. 
D)  the rate constant for the formation of products is k2. 
A)  enzyme reactions are altered by pH. 
B)  enzyme reactions depend on the concentration of the substrate. 
C)  enzyme reactions depend on the concentration of the enzyme and its recycling. 
D)  the rate constant for the formation of products is k2.

Question 3

Rational drug design involves the study of enzyme structure and the use of computers to generate structures of possible enzyme inhibitors.

Accepted Answer

A) True 
 B)False

Question 4

A noncompetitive inhibitor can bind to either the enzyme or the enzyme-substrate complex.

Accepted Answer

A) True 
 B)False

Question 5

At the beginning of an enzyme-catalyzed reaction the is negligible.

Accepted Answer

A)  formation of ES 
B)  formation of E + P 
C)  conversion of ES to E + S 
D)  disappearance of ES 
A)  formation of ES 
B)  formation of E + P 
C)  conversion of ES to E + S 
D)  disappearance of ES

Question 6

In a first order chemical reaction, the velocity of the reaction is proportional to the , while in a zero order reaction, the velocity of the reaction is proportional to the .

Accepted Answer

A)  amount of enzyme; concentration of substrate 
B)  concentration of substrate; amount of enzyme 
C)  concentration of substrate; speed of the reaction 
D)  speed of the reaction; concentration of substrate 
A)  amount of enzyme; concentration of substrate 
B)  concentration of substrate; amount of enzyme 
C)  concentration of substrate; speed of the reaction 
D)  speed of the reaction; concentration of substrate

Question 7

The reason to rewrite the Michaelis-Menten equation such as the Lineweaver-Burk plot) is to

Accepted Answer

A)  visualize reactions better. 
B)  form enzyme kinetic data as a hyperbolic curve. 
C)  calculate catalytic proficiency. 
D)  calculate Vmax and Km. 
A)  visualize reactions better. 
B)  form enzyme kinetic data as a hyperbolic curve. 
C)  calculate catalytic proficiency. 
D)  calculate Vmax and Km.

Question 8

The ratio of kcat/Km for each of two different substrates present in equal concentrations in an enzyme reaction will measure enzyme affinity because

Accepted Answer

A)  the rates of P formation are given by the values found for each substrate. 
B)  the rates of P formation are the same for each substrate. 
C)  it is an indication of the formation of ES for each substrate. 
D)  All of the above 
A)  the rates of P formation are given by the values found for each substrate. 
B)  the rates of P formation are the same for each substrate. 
C)  it is an indication of the formation of ES for each substrate. 
D)  All of the above

Question 9

The lower, higher) the value of Km, the less, more) tightly the enzyme is bound to the substrate.

Accepted Answer

A)  lower, less 
B)  lower, more 
C)  higher, less 
D)  higher, more 
E)  B and C 
A)  lower, less 
B)  lower, more 
C)  higher, less 
D)  higher, more 
E)  B and C

Question 10

The quaternary structure of hemoglobin changes from the T state to the R state .

Accepted Answer

A)  only after four molecules of O2 are bound 
B)  after the binding of one molecule of O2 causes a change in the primary structure 
C)  when hemoglobin is completely deoxygenated 
D)  when at least one subunit on each dimeric unit αβ dimer) is oxygenated 
A)  only after four molecules of O2 are bound 
B)  after the binding of one molecule of O2 causes a change in the primary structure 
C)  when hemoglobin is completely deoxygenated 
D)  when at least one subunit on each dimeric unit αβ dimer) is oxygenated

Question 11

The Michaelis constant, Km, is equal to the .

Accepted Answer

A)  maximum velocity that any given enzyme reaction can achieve 
B)  substrate concentration which gives the best enzyme assay for an enzyme reaction 
C)  substrate concentration when the rate is equal to half its maximal value 
D)  maximum velocity divided by two 
A)  maximum velocity that any given enzyme reaction can achieve 
B)  substrate concentration which gives the best enzyme assay for an enzyme reaction 
C)  substrate concentration when the rate is equal to half its maximal value 
D)  maximum velocity divided by two

Question 12

Select the correct class of enzyme for each of these reactions. A) isomerase
B) ligase
C) lyase
D) transferase
E) oxidoreductase
F) hydrolase
-Polypeptide + H2O → Amino acids

Accepted Answer

Question 13

Which might be a method used for distinguishing among several mechanistic possibilities in a multi-substrate reaction?

Accepted Answer

A)  Measure Km in the presence of one substrate at a time. 
B)  Measure the rate with respect to one substrate while varying the concentration of another substrate. 
C)  Measure the rate while adding inactivators for all but one substrate. 
D)  Any of the above 
A)  Measure Km in the presence of one substrate at a time. 
B)  Measure the rate with respect to one substrate while varying the concentration of another substrate. 
C)  Measure the rate while adding inactivators for all but one substrate. 
D)  Any of the above

Question 14

Which statement is false about the sequential theory?

Accepted Answer

A)  It treats the concerted theory as a limiting simple case. 
B)  It allows for a distribution of high and low affinity subunits in the same protein. 
C)  It assumes more than one conformation of a particular subunit can have high affinity for the ligand. 
D)  It is also called the ligand-induced theory and is more general than the concerted theory. 
A)  It treats the concerted theory as a limiting simple case. 
B)  It allows for a distribution of high and low affinity subunits in the same protein. 
C)  It assumes more than one conformation of a particular subunit can have high affinity for the ligand. 
D)  It is also called the ligand-induced theory and is more general than the concerted theory.

Question 15

Select the correct class of enzyme for each of these reactions. A) isomerase
B) ligase
C) lyase
D) transferase
E) oxidoreductase
F) hydrolase
-Glucose-6-phosphate →
Fructose-6-phosphate

Accepted Answer

The answer of Select the correct class of enzyme for...

Question 16

The initial velocity of an enzyme reaction v0) describes

Accepted Answer

A)  the concentration of the enzyme at maximal velocity. 
B)  the concentration of substrate at maximal velocity. 
C)  the concentration of both at the start of the reaction. 
D)  the rate of the reaction at when the substrate and enzyme are first mixed. 
A)  the concentration of the enzyme at maximal velocity. 
B)  the concentration of substrate at maximal velocity. 
C)  the concentration of both at the start of the reaction. 
D)  the rate of the reaction at when the substrate and enzyme are first mixed.

Question 17

In a multienzyme complex the process of directly transferring a product of one reaction to the next active site without allowing it to enter the bulk solvent is termed .

Accepted Answer

A)  a ping-pong reaction 
B)  metabolite channeling 
C)  the activity pathway 
D)  the sequential mode 
A)  a ping-pong reaction 
B)  metabolite channeling 
C)  the activity pathway 
D)  the sequential mode

Question 18

Interconvertible enzymes .

Accepted Answer

A)  are those controlled by covalent modification 
B)  follow a concerted mechanism to go back and forth between the T and R states 
C)  catalyze reactions to covalently modify another enzyme 
D)  are allosteric modulators 
A)  are those controlled by covalent modification 
B)  follow a concerted mechanism to go back and forth between the T and R states 
C)  catalyze reactions to covalently modify another enzyme 
D)  are allosteric modulators

Question 19

Very few catalytic proficiency values are known because many nonenzymatic reaction rates are so slow that they are difficult to measure.

Accepted Answer

A) True 
 B)False

Question 20

Which statement is false about allosteric regulation?

Accepted Answer

A)  It is usually the mode of regulation for the last step in reaction pathways since this step produces the final product. 
B)  Cellular response is faster with allosteric control than by controlling enzyme concentration in the cell. 
C)  The regulation usually is important to the conservation of energy and materials in cells. 
D)  Allosteric modulators bind non-covalently at sites other than the active site and induce conformational changes in the enzyme. 
A)  It is usually the mode of regulation for the last step in reaction pathways since this step produces the final product. 
B)  Cellular response is faster with allosteric control than by controlling enzyme concentration in the cell. 
C)  The regulation usually is important to the conservation of energy and materials in cells. 
D)  Allosteric modulators bind non-covalently at sites other than the active site and induce conformational changes in the enzyme.

Exam 5: Properties of Enzymes

The time that is required for an enzyme to convert one substrate molecule into one product molecule is

The main difference between chemical and enzyme kinetics is that

Rational drug design involves the study of enzyme structure and the use of computers to generate structures of possible enzyme inhibitors.

A noncompetitive inhibitor can bind to either the enzyme or the enzyme-substrate complex.

At the beginning of an enzyme-catalyzed reaction the is negligible.

In a first order chemical reaction, the velocity of the reaction is proportional to the , while in a zero order reaction, the velocity of the reaction is proportional to the .

The reason to rewrite the Michaelis-Menten equation such as the Lineweaver-Burk plot) is to

The ratio of kcat/Km for each of two different substrates present in equal concentrations in an enzyme reaction will measure enzyme affinity because

The lower, higher) the value of Km, the less, more) tightly the enzyme is bound to the substrate.

The quaternary structure of hemoglobin changes from the T state to the R state .

The Michaelis constant, Km, is equal to the .

Select the correct class of enzyme for each of these reactions. A) isomerase B) ligase C) lyase D) transferase E) oxidoreductase F) hydrolase -Polypeptide + H2O → Amino acids

Which might be a method used for distinguishing among several mechanistic possibilities in a multi-substrate reaction?

Which statement is false about the sequential theory?

Select the correct class of enzyme for each of these reactions. A) isomerase B) ligase C) lyase D) transferase E) oxidoreductase F) hydrolase -Glucose-6-phosphate → Fructose-6-phosphate

The initial velocity of an enzyme reaction v0) describes

In a multienzyme complex the process of directly transferring a product of one reaction to the next active site without allowing it to enter the bulk solvent is termed .

Interconvertible enzymes .

Very few catalytic proficiency values are known because many nonenzymatic reaction rates are so slow that they are difficult to measure.

Which statement is false about allosteric regulation?

Introduction to Biochemistry

Water

Amino Acids and the Primary Structures of Proteins

Proteins: Three-Dimensional Structure and Function

Mechanisms of Enzymes

Coenzymes and Vitamins

Carbohydrates

Lipids and Membranes

Introduction to Metabolism

Glycolysis

Gluconeogenesis, the Pentose Phosphate Pathway, and Glycogen Metabolism

The Citric Acid Cycle

Electron Transport and Oxidative Phosphorylation

Photosynthesis

Lipid Metabolism

Amino Acid Metabolism

Nucleotide Metabolism

Nucleic Acids

Dna Replication, Repair, and Recombination

Transcription and Rna Processing

Protein Synthesis

Recombinant Dna Technology

Filters

The ratio of k_cat/K_mfor each of two different substrates present in equal concentrations in an enzyme reaction will measure enzyme affinity because

The lower, higher) the value of K_m, the less, more) tightly the enzyme is bound to the substrate.

The Michaelis constant, K_m, is equal to the .

Select the correct class of enzyme for each of these reactions. A) isomerase B) ligase C) lyase D) transferase E) oxidoreductase F) hydrolase -Polypeptide + H₂O → Amino acids

The initial velocity of an enzyme reaction v₀) describes