Question 1

The main difference between a catalyzed and an uncatalyzed reaction is that

Accepted Answer

A)  the activation energy of the catalyzed reaction is lower. 
B)  the catalyzed reaction has a more favorable free energy change. 
C)  the catalyzed reaction has a more favorable enthalpy change. 
D)  the catalyzed reaction has a more favorable entropy change. 
A)  the activation energy of the catalyzed reaction is lower. 
B)  the catalyzed reaction has a more favorable free energy change. 
C)  the catalyzed reaction has a more favorable enthalpy change. 
D)  the catalyzed reaction has a more favorable entropy change.

Question 2

A transition state analogue

Accepted Answer

A)  binds tightly to the enzyme 
B)  enhances the activity of the enzyme when bound to it 
C)  forms a complex with the enzyme that is energetically stable compared to the enzyme-substrate complex 
D)  will bind to the enzyme by the lock-and-key mechanism rather than the induced-fit mechanism 
A)  binds tightly to the enzyme 
B)  enhances the activity of the enzyme when bound to it 
C)  forms a complex with the enzyme that is energetically stable compared to the enzyme-substrate complex 
D)  will bind to the enzyme by the lock-and-key mechanism rather than the induced-fit mechanism

Question 3

Exhibit 6A This is a reaction going on in your muscle cells right this very minute:
  The enzyme triose phosphate isomerase catalyzes this reaction in the forward direction as part of the glycolytic pathway.It follows simple Michaelis-Menten kinetics:
  Typical cellular concentrations: triose phosphate isomerase = 0.1 nM
Dihydroxyacetone phosphate = 5 µM glyceraldehyde-3-phosphate = 2 µM
Refer to Exhibit 6A."Restrainin" is an inhibitor of triose phosphate isomerase.When it is added to cells at a concentration of 0.4 nM,the enzyme's apparent KM for the substrate is altered to 100 µM,but the Vmax is unchanged.
In the following graph,which line best represents the Lineweaver-Burk plot obtained in the presence of restrainin?

Accepted Answer

A)  A 
B)  B 
C)  C 
D)  D 
E)  E 
A)  A 
B)  B 
C)  C 
D)  D 
E)  E

Question 4

The initial rate of an enzymatic reaction is usually determined in order to assure that

Accepted Answer

A)  the enzyme is active 
B)  there is no reverse reaction of product to the enzyme-substrate complex 
C)  the substrate is not used up 
D)  the experiment can be completed quickly 
A)  the enzyme is active 
B)  there is no reverse reaction of product to the enzyme-substrate complex 
C)  the substrate is not used up 
D)  the experiment can be completed quickly

Question 5

What effect does a catalyst have on the DG° of a reaction?

Accepted Answer

A)  A catalyst lowers the DG°. 
B)  A catalyst raises the DG°. 
C)  A catalyst has no effect on the DG°. 
D)  It depend on the specific catalyst. 
A)  A catalyst lowers the DG°. 
B)  A catalyst raises the DG°. 
C)  A catalyst has no effect on the DG°. 
D)  It depend on the specific catalyst.

Question 6

In the reaction catalyzed by aspartate transcarbamoylase,a graph in which the rate is plotted against the concentration of substrate

Accepted Answer

A)  is sigmoidal, characteristic of an allosteric enzyme 
B)  shows that noncooperative kinetics are observed 
C)  shows that the reaction is zero order 
D)  is hyperbolic, characteristic of a nonallosteric enzyme 
A)  is sigmoidal, characteristic of an allosteric enzyme 
B)  shows that noncooperative kinetics are observed 
C)  shows that the reaction is zero order 
D)  is hyperbolic, characteristic of a nonallosteric enzyme

Question 7

The substrate-enzyme (E-S) complex

Accepted Answer

A)  always proceeds to form the products rapidly. 
B)  always breaks down to form free enzyme and substrate. 
C)  always breaks down to form free enzyme and product. 
D)  may break down to form free enzyme and substrate, or free enzyme and product. 
A)  always proceeds to form the products rapidly. 
B)  always breaks down to form free enzyme and substrate. 
C)  always breaks down to form free enzyme and product. 
D)  may break down to form free enzyme and substrate, or free enzyme and product.

Question 8

Exhibit 6A This is a reaction going on in your muscle cells right this very minute:
  The enzyme triose phosphate isomerase catalyzes this reaction in the forward direction as part of the glycolytic pathway.It follows simple Michaelis-Menten kinetics:
  Typical cellular concentrations: triose phosphate isomerase = 0.1 nM
Dihydroxyacetone phosphate = 5 µM glyceraldehyde-3-phosphate = 2 µM
Refer to Exhibit 6A.What is the KM of the enzyme?

Accepted Answer

A)  10 nM 
B)  0.1 µM 
C)  1 µM 
D)  10 µM 
A)  10 nM 
B)  0.1 µM 
C)  1 µM 
D)  10 µM

Question 9

If an inhibitor changes the slope of the Lineweaver-Burk graph,but not the y-intercept,it is this type of inhibition:

Accepted Answer

A)  Competitive. 
B)  Non-competitive. 
C)  Mixed Inhibition (uncompetitive inhibition). 
D)  You cannot tell from the data given. 
E)  More than one answer is correct. 
A)  Competitive. 
B)  Non-competitive. 
C)  Mixed Inhibition (uncompetitive inhibition). 
D)  You cannot tell from the data given. 
E)  More than one answer is correct.

Question 10

What effect is seen on a Lineweaver-Burk graph when a non-competitive inhibitor is added?

Accepted Answer

A)  The y-intercept is changed, but not change the slope of the line. 
B)  The slope of the line is changed, but not the y-intercept. 
C)  Both the y-intercept and the slope of the line are changed. 
D)  Neither the y-intercept not the slope of the line is changed. 
A)  The y-intercept is changed, but not change the slope of the line. 
B)  The slope of the line is changed, but not the y-intercept. 
C)  Both the y-intercept and the slope of the line are changed. 
D)  Neither the y-intercept not the slope of the line is changed.

Question 11

Which of the following describes the unique importance of protein Kinase Mæ (PKMæ)?

Accepted Answer

A)  It is a protein kinase 
B)  It uses ATP to phosphorylate a substrate 
C)  It is an allosteric enzyme 
D)  It has been implicated in the formation of long-term memories 
A)  It is a protein kinase 
B)  It uses ATP to phosphorylate a substrate 
C)  It is an allosteric enzyme 
D)  It has been implicated in the formation of long-term memories

Question 12

Exhibit 6A This is a reaction going on in your muscle cells right this very minute:
  The enzyme triose phosphate isomerase catalyzes this reaction in the forward direction as part of the glycolytic pathway.It follows simple Michaelis-Menten kinetics:
  Typical cellular concentrations: triose phosphate isomerase = 0.1 nM
Dihydroxyacetone phosphate = 5 µM glyceraldehyde-3-phosphate = 2 µM
Refer to Exhibit 6A.What is the Vmax of the enzyme?

Accepted Answer

A)  90 nM/s 
B)  4500 µM/s 
C)  200 µM/s 
D)  0.5 M/s 
A)  90 nM/s 
B)  4500 µM/s 
C)  200 µM/s 
D)  0.5 M/s

Question 13

The Michaelis-Menten approach to describing the kinetics of an enzyme-catalyzed reaction makes which of the following assumptions about the conversion of product into substrate?

Accepted Answer

A)  The product binds reversibly to the enzyme in order to be converted into the substrate. 
B)  The product is not converted to substrate to any appreciable extent. 
C)  The product is converted to substrate following simple first order kinetics. 
D)  The product is converted to substrate following simple second order kinetics. 
A)  The product binds reversibly to the enzyme in order to be converted into the substrate. 
B)  The product is not converted to substrate to any appreciable extent. 
C)  The product is converted to substrate following simple first order kinetics. 
D)  The product is converted to substrate following simple second order kinetics.

Question 14

The order of a reaction can be determined from the balanced equation for the reaction.

Accepted Answer

A) True 
 B)False

Question 15

Which of the following is true about the enzyme chymotrypsin?

Accepted Answer

A)  The enzyme can cleave peptides. 
B)  The enzyme can cleave esters. 
C)  The enzyme only binds to aromatic substrates. 
D)  The enzyme can cleave substrates which are not naturally occurring. 
E)  All of these are true. 
A)  The enzyme can cleave peptides. 
B)  The enzyme can cleave esters. 
C)  The enzyme only binds to aromatic substrates. 
D)  The enzyme can cleave substrates which are not naturally occurring. 
E)  All of these are true.

Question 16

Exhibit 6A This is a reaction going on in your muscle cells right this very minute:
  The enzyme triose phosphate isomerase catalyzes this reaction in the forward direction as part of the glycolytic pathway.It follows simple Michaelis-Menten kinetics:
  Typical cellular concentrations: triose phosphate isomerase = 0.1 nM
Dihydroxyacetone phosphate = 5 µM glyceraldehyde-3-phosphate = 2 µM
Refer to Exhibit 6A.What is the actual velocity of the forward reaction under physiologic conditions?

Accepted Answer

A)  2 nM/s 
B)  45 nM/s 
C)  500 nM/s 
D)  30 nM/s 
A)  2 nM/s 
B)  45 nM/s 
C)  500 nM/s 
D)  30 nM/s

Question 17

When the substrate concentration is low,an enzyme reaction

Accepted Answer

A)  will display zero-order kinetics. 
B)  will display first-order kinetics. 
C)  will display second-order kinetics. 
D)  will denature and cease to function. 
A)  will display zero-order kinetics. 
B)  will display first-order kinetics. 
C)  will display second-order kinetics. 
D)  will denature and cease to function.

Question 18

For competitive inhibition

Accepted Answer

A)  the value of KM decreases 
B)  the value of Vmax decreases 
C)  it is possible to overcome the effect of the inhibitor by increasing the concentration of substrate 
D)  none of the above 
A)  the value of KM decreases 
B)  the value of Vmax decreases 
C)  it is possible to overcome the effect of the inhibitor by increasing the concentration of substrate 
D)  none of the above

Question 19

As catalysts,enzymes are

Accepted Answer

A)  significantly less effective than nonenzymatic catalysts 
B)  slightly less effective than nonenzymatic catalysts 
C)  significantly more effective than nonenzymatic catalysts 
D)  slightly more effective than nonenzymatic catalysts 
A)  significantly less effective than nonenzymatic catalysts 
B)  slightly less effective than nonenzymatic catalysts 
C)  significantly more effective than nonenzymatic catalysts 
D)  slightly more effective than nonenzymatic catalysts

Question 20

Generally speaking,a competitive inhibitor and the substrate cannot both bind to the enzyme at the same time.

Accepted Answer

A) True 
 B)False

The main difference between a catalyzed and an uncatalyzed reaction is that

A transition state analogue

The initial rate of an enzymatic reaction is usually determined in order to assure that

What effect does a catalyst have on the DG° of a reaction?

In the reaction catalyzed by aspartate transcarbamoylase,a graph in which the rate is plotted against the concentration of substrate

The substrate-enzyme (E-S) complex

If an inhibitor changes the slope of the Lineweaver-Burk graph,but not the y-intercept,it is this type of inhibition:

What effect is seen on a Lineweaver-Burk graph when a non-competitive inhibitor is added?

Which of the following describes the unique importance of protein Kinase Mæ (PKMæ)?

The Michaelis-Menten approach to describing the kinetics of an enzyme-catalyzed reaction makes which of the following assumptions about the conversion of product into substrate?

The order of a reaction can be determined from the balanced equation for the reaction.

Which of the following is true about the enzyme chymotrypsin?

When the substrate concentration is low,an enzyme reaction

For competitive inhibition

As catalysts,enzymes are

Generally speaking,a competitive inhibitor and the substrate cannot both bind to the enzyme at the same time.

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, Mechanisms, and Control

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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Exam 6: The Behavior of Proteins: Enzymes

The main difference between a catalyzed and an uncatalyzed reaction is that

A transition state analogue

The initial rate of an enzymatic reaction is usually determined in order to assure that

What effect does a catalyst have on the DG° of a reaction?

In the reaction catalyzed by aspartate transcarbamoylase,a graph in which the rate is plotted against the concentration of substrate

The substrate-enzyme (E-S) complex

If an inhibitor changes the slope of the Lineweaver-Burk graph,but not the y-intercept,it is this type of inhibition:

What effect is seen on a Lineweaver-Burk graph when a non-competitive inhibitor is added?

Which of the following describes the unique importance of protein Kinase Mæ (PKMæ)?

The Michaelis-Menten approach to describing the kinetics of an enzyme-catalyzed reaction makes which of the following assumptions about the conversion of product into substrate?

The order of a reaction can be determined from the balanced equation for the reaction.

Which of the following is true about the enzyme chymotrypsin?

When the substrate concentration is low,an enzyme reaction

For competitive inhibition

As catalysts,enzymes are

Generally speaking,a competitive inhibitor and the substrate cannot both bind to the enzyme at the same time.

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, Mechanisms, and Control

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