Question 1

The Michaelis constant is defined as _____.

Accepted Answer

A)  KM = k2 / k1 
B)  KM = (k2 + k-1) / k1 
C)  KM = (k2 - k-1) / k1 
D)  KM = (k2 + k1) / k-1 
E)  KM = (k2 - k1) / k-1 
A)  KM = k2 / k1 
B)  KM = (k2 + k-1) / k1 
C)  KM = (k2 - k-1) / k1 
D)  KM = (k2 + k1) / k-1 
E)  KM = (k2 - k1) / k-1 B

Question 2

A plot of velocity versus substrate concentration for a simple enzyme-catalyzed reaction produces a _____. This indicates that at some point, the enzyme is _____.

Accepted Answer

A)  straight line; inhibited by product 
B)  hyperbolic curve; saturated with substrate 
C)  sigmoidal curve; inhibited by substrate 
D)  hyperbolic curve; activated by substrate 
E)  sigmoidal curve; saturated with substrate 
A)  straight line; inhibited by product 
B)  hyperbolic curve; saturated with substrate 
C)  sigmoidal curve; inhibited by substrate 
D)  hyperbolic curve; activated by substrate 
E)  sigmoidal curve; saturated with substrate B

Question 3

Some irreversible inhibitors are called _____ because they bind to the active site of the enzyme and begin the catalytic process, just like a normal substrate.

Accepted Answer

A)  irreversible substrates 
B)  suicide substrates 
C)  noncompetitive substrates 
D)  ping pong substrates 
E)  allosteric substrates 
A)  irreversible substrates 
B)  suicide substrates 
C)  noncompetitive substrates 
D)  ping pong substrates 
E)  allosteric substrates B

Question 4

Which of the following represents a rapid and reversible mechanism to alter the activity of an enzyme?

Accepted Answer

A)  synthesis of more enzyme to increase activity 
B)  degradation of enzyme to decrease activity 
C)  covalent attachment of a phosphate group to increase or decrease activity 
D)  movement of an enzyme from one cellular compartment to another 
E)  none of the above 
A)  synthesis of more enzyme to increase activity 
B)  degradation of enzyme to decrease activity 
C)  covalent attachment of a phosphate group to increase or decrease activity 
D)  movement of an enzyme from one cellular compartment to another 
E)  none of the above

Question 5

When a substrate and enzyme interact, the first chemical species formed is the _____.

Accepted Answer

A)  enzyme-substrate complex 
B)  enzyme-transition state complex 
C)  enzyme-product complex 
D)  enzyme plus product 
E)  none of the above 
A)  enzyme-substrate complex 
B)  enzyme-transition state complex 
C)  enzyme-product complex 
D)  enzyme plus product 
E)  none of the above

Question 6

What amino acid performs the nucleophilic attack during the chymotrypsin mechanism?

Accepted Answer

A)  Ser 
B)  His 
C)  Lys 
D)  Cys 
E)  Thr 
A)  Ser 
B)  His 
C)  Lys 
D)  Cys 
E)  Thr

Question 7

What does the KI for a competitive inhibitor mean?

Accepted Answer

A)  Higher KI values mean tighter binding to ES complex. 
B)  Lower KI values mean tighter binding to ES complex. 
C)  Higher KI values mean tighter binding to the enzyme. 
D)  Lower KI values mean tighter binding to the enzyme. 
E)  KI values tell nothing about inhibitor binding. 
A)  Higher KI values mean tighter binding to ES complex. 
B)  Lower KI values mean tighter binding to ES complex. 
C)  Higher KI values mean tighter binding to the enzyme. 
D)  Lower KI values mean tighter binding to the enzyme. 
E)  KI values tell nothing about inhibitor binding.

Question 8

The catalytic constant, or kcat, is also known as the _____.

Accepted Answer

A)  turnover number 
B)  saturation number 
C)  catalytic efficiency number 
D)  diffusion number 
E)  Menten number 
A)  turnover number 
B)  saturation number 
C)  catalytic efficiency number 
D)  diffusion number 
E)  Menten number

Question 9

Based on the figures below, which of the following expressions would be correct?

Accepted Answer

A)  Vmax = 1/B 
B)  C = 1/Vmax 
C)  D = Vmax 
D)  D = 1/Vmax 
E)  A = 1/Vmax 
A)  Vmax = 1/B 
B)  C = 1/Vmax 
C)  D = Vmax 
D)  D = 1/Vmax 
E)  A = 1/Vmax

Question 10

Which of the following indicates that an enzyme has evolved to its most efficient form?

Accepted Answer

A)  kcat is a large number 
B)  KM is a small number 
C)  KM is a large number 
D)  kcat/KM is a small number 
E)  kcat/KM is near the diffusion-controlled limit 
A)  kcat is a large number 
B)  KM is a small number 
C)  KM is a large number 
D)  kcat/KM is a small number 
E)  kcat/KM is near the diffusion-controlled limit

Question 11

An inhibitor that binds to the active site only in the absence of the substrate and in a reversible fashion is a(n) _____.

Accepted Answer

A)  allosteric inhibitor 
B)  suicide substrate 
C)  mixed inhibitor 
D)  noncompetitive inhibitor 
E)  competitive inhibitor 
A)  allosteric inhibitor 
B)  suicide substrate 
C)  mixed inhibitor 
D)  noncompetitive inhibitor 
E)  competitive inhibitor

Question 12

The highest point in a reaction coordinate diagram represents _____.

Accepted Answer

A)  an intermediate of the reaction pathway 
B)  the reactants in an exergonic reaction 
C)  the products in an endergonic reaction 
D)  the transition state 
E)  the overall $\Delta$ G for the reaction 
A)  an intermediate of the reaction pathway 
B)  the reactants in an exergonic reaction 
C)  the products in an endergonic reaction 
D)  the transition state 
E)  the overall $\Delta$ G for the reaction

Question 13

When [S] = KM, $\nu$0 = (_____) × (Vmax).

Accepted Answer

A)  [S] 
B)  0.75 
C)  0.5 
D)  KM 
E)  kcat 
A)  [S] 
B)  0.75 
C)  0.5 
D)  KM 
E)  kcat

Question 14

In the lysosome reaction, the carbohydrate substrate is in the _____ conformation providing a contribution of catalytic energy via the ____ distortion.

Accepted Answer

A)  half-chair; electrostatic 
B)  chair; strain 
C)  boat; strain 
D)  boat; electrostatic 
E)  half-chair; strain 
A)  half-chair; electrostatic 
B)  chair; strain 
C)  boat; strain 
D)  boat; electrostatic 
E)  half-chair; strain

Question 15

If the Asp in the chymotrypsin active site was mutated to another amino acid, which of the following would be considered an invisible mutation in that it is least likely to affect the function of the enzyme?

Accepted Answer

A)  Asp $\rightarrow$ Asn 
B)  Asp $\rightarrow$Glu 
C)  Asp $\rightarrow$His 
D)  Asp $\rightarrow$ Ser 
E)  Asp $\rightarrow$Lys 
A)  Asp $\rightarrow$ Asn 
B)  Asp $\rightarrow$Glu 
C)  Asp $\rightarrow$His 
D)  Asp $\rightarrow$ Ser 
E)  Asp $\rightarrow$Lys

Question 16

An enzyme that forms a covalent bond with its substrate during a reaction is considered to undergo _____.

Accepted Answer

A)  acid-base catalysis 
B)  covalent catalysis 
C)  electrophilic catalysis 
D)  metal ion catalysis 
E)  none of the above 
A)  acid-base catalysis 
B)  covalent catalysis 
C)  electrophilic catalysis 
D)  metal ion catalysis 
E)  none of the above

Question 17

If a Lineweaver-Burk plot gave a line with an equation of y = 0.25 x + 0.34, what are the values of KM and Vmax if the substrate concentration is in mM and the velocity in mM/s?

Accepted Answer

A)  0.085 mM and 0.34 mM/s 
B)  2.9 mM and 0.023 mM/s 
C)  0.74 mM and 2.9 mM/s 
D)  0.37 mM and 1.4 mM/s 
E)  1.35 mM and .034 mM/s 
A)  0.085 mM and 0.34 mM/s 
B)  2.9 mM and 0.023 mM/s 
C)  0.74 mM and 2.9 mM/s 
D)  0.37 mM and 1.4 mM/s 
E)  1.35 mM and .034 mM/s

Question 18

What three amino acids are found in the catalytic triad of chymotrypsin?

Accepted Answer

A)  Glu, His, Thr 
B)  Ser, Arg, Cys 
C)  Asp, His, Ser 
D)  Cys, Lys, Glu 
E)  Asn, His, Thr 
A)  Glu, His, Thr 
B)  Ser, Arg, Cys 
C)  Asp, His, Ser 
D)  Cys, Lys, Glu 
E)  Asn, His, Thr

Question 19

In ______, the inhibitor binds to a site involved in both substrate binding and catalysis.

Accepted Answer

competitiv

Question 20

The ability for an enzyme to change its shape upon substrate binding represents the concept of _____.

Accepted Answer

A)  lock and key 
B)  induced fit 
C)  proximity and orientation effects 
D)  covalent catalysis 
E)  none of the above 
A)  lock and key 
B)  induced fit 
C)  proximity and orientation effects 
D)  covalent catalysis 
E)  none of the above

Exam 4: Proteins Iienzymes

The Michaelis constant is defined as _____.

A plot of velocity versus substrate concentration for a simple enzyme-catalyzed reaction produces a _____. This indicates that at some point, the enzyme is _____.

Some irreversible inhibitors are called _____ because they bind to the active site of the enzyme and begin the catalytic process, just like a normal substrate.

Which of the following represents a rapid and reversible mechanism to alter the activity of an enzyme?

When a substrate and enzyme interact, the first chemical species formed is the _____.

What amino acid performs the nucleophilic attack during the chymotrypsin mechanism?

What does the KI for a competitive inhibitor mean?

The catalytic constant, or kcat, is also known as the _____.

Based on the figures below, which of the following expressions would be correct?

Which of the following indicates that an enzyme has evolved to its most efficient form?

An inhibitor that binds to the active site only in the absence of the substrate and in a reversible fashion is a(n) _____.

The highest point in a reaction coordinate diagram represents _____.

When [S] = KM, ν\nuν 0 = (_____) × (Vmax).

In the lysosome reaction, the carbohydrate substrate is in the _____ conformation providing a contribution of catalytic energy via the ____ distortion.

If the Asp in the chymotrypsin active site was mutated to another amino acid, which of the following would be considered an invisible mutation in that it is least likely to affect the function of the enzyme?

An enzyme that forms a covalent bond with its substrate during a reaction is considered to undergo _____.

If a Lineweaver-Burk plot gave a line with an equation of y = 0.25 x + 0.34, what are the values of KM and Vmax if the substrate concentration is in mM and the velocity in mM/s?

What three amino acids are found in the catalytic triad of chymotrypsin?

In ______, the inhibitor binds to a site involved in both substrate binding and catalysis.

The ability for an enzyme to change its shape upon substrate binding represents the concept of _____.

The Chemical Foundations of Biochemistry

Nucleic Acids

Proteins I

Membranes and an Introduction to Signal Transduction

Carbohydrates I

The Common Catabolic Pathway

Carbohydrates II

Lipids I

Lipids II

Amine Metabolism

Metabolism Integration

Nucleotide Deoxynucleotide Metabolism

Dna Replication, Damage and Repair

Rna Synthesis

Protein

Control of Gene

Determination of Macromolecular Structure

Allosterism and Receptor-Ligand

Designer Proteins and Protein Folding

Biomolecule Purification

Bioinformatics and Omics

Signal

Protein Trafficking

Photosynthesis Nitrogen

Filters

A plot of velocity versus substrate concentration for a simple enzyme-catalyzed reaction produces a _. This indicates that at some point, the enzyme is _.

What does the K_I for a competitive inhibitor mean?

The catalytic constant, or k_cat, is also known as the _____.

When [S] = K_M, $\nu$ ₀= (_____) × (V_max).

In the lysosome reaction, the carbohydrate substrate is in the _ conformation providing a contribution of catalytic energy via the distortion.

If a Lineweaver-Burk plot gave a line with an equation of y = 0.25 x + 0.34, what are the values of K_M and V_max if the substrate concentration is in mM and the velocity in mM/s?