Question 1

All of the following statements are true about the relationships between [S], Km and Vmax EXCEPT:

Accepted Answer

A)  As the [S] is increased, v approaches the limiting value, Vmax. 
B)  Km = Vmax/2. 
C)  The rate of the reaction, v, follows a first order rate equation v = K'[A] and K' = Vmax/Km. 
D)  The rate of product formed, v, is at Vmax when [S] >> Km. 
E)  Km and Vmax assist in finding the rate of the enzyme catalyzed reaction only if the reaction is irreversible. 
A)  As the [S] is increased, v approaches the limiting value, Vmax. 
B)  Km = Vmax/2. 
C)  The rate of the reaction, v, follows a first order rate equation v = K'[A] and K' = Vmax/Km. 
D)  The rate of product formed, v, is at Vmax when [S] >> Km. 
E)  Km and Vmax assist in finding the rate of the enzyme catalyzed reaction only if the reaction is irreversible.

Question 2

Penicillin is an example of a mechanism-based enzyme inactivator and is a(n):

Accepted Answer

A)  competitive inhibitor. 
B)  noncompetitive inhibitor. 
C)  suicide substrate. 
D)  uncompetitive inhibitor. 
E)  none of the above. 
A)  competitive inhibitor. 
B)  noncompetitive inhibitor. 
C)  suicide substrate. 
D)  uncompetitive inhibitor. 
E)  none of the above.

Question 3

All are characteristics of ordered single-displacement reactions EXCEPT:

Accepted Answer

A)  Lineweaver-Burk plots with lines that intersect to the left of the 1/v axis. 
B)  a chemically modified enzyme-intermediate. 
C)  the lack of any exchange reaction activity. 
D)  the lack of competitive substrate effects. 
E)  single substrate initial binding activity. 
A)  Lineweaver-Burk plots with lines that intersect to the left of the 1/v axis. 
B)  a chemically modified enzyme-intermediate. 
C)  the lack of any exchange reaction activity. 
D)  the lack of competitive substrate effects. 
E)  single substrate initial binding activity.

Question 4

All of the following statements about noncompetitive inhibition are true EXCEPT:

Accepted Answer

A)  They interact with the enzyme as well as the enzyme-substrate complex. 
B)  Increasing the concentration of [S] can overcome the inhibition. 
C)  The Vmax value does not remain the same as for a reaction that is not inhibited. 
D)  The inhibitor can cause a conformational change in the enzyme. 
E)  The inhibitor binds to a different site than does the substrate. 
A)  They interact with the enzyme as well as the enzyme-substrate complex. 
B)  Increasing the concentration of [S] can overcome the inhibition. 
C)  The Vmax value does not remain the same as for a reaction that is not inhibited. 
D)  The inhibitor can cause a conformational change in the enzyme. 
E)  The inhibitor binds to a different site than does the substrate.

Question 5

Carbonic anhydrase has two substrates, carbon dioxide and bicarbonate, which are both converted to carbonic acid. Kinetic data for each is given below. Typical values for Kcat/Km range from less than 1 mM-1sec-1 to as high as 2.8×105 mM-1sec-1. What can be said about the Kcat/Km for CO2?
Substrate
Km (mM)
Kcat (sec-1)
Kcat/Km (m M-1sec-1)
CO2
HCO3-
12
26
1×106
4×105
8)3×104
1.5×104

Accepted Answer

A)  carbonic anhydrase binds CO2 well but poorly converts it to carbonic acid 
B)  carbonic anhydrase binds CO2 poorly but effectively converts it to carbonic acid 
C)  carbonic anhydrase binds CO2 well and converts it to carbonic acid very well 
D)  carbonic anhydrase binds CO2 poorly and poorly converts it to carbonic acid 
E)  the data above is useless for this question 
A)  carbonic anhydrase binds CO2 well but poorly converts it to carbonic acid 
B)  carbonic anhydrase binds CO2 poorly but effectively converts it to carbonic acid 
C)  carbonic anhydrase binds CO2 well and converts it to carbonic acid very well 
D)  carbonic anhydrase binds CO2 poorly and poorly converts it to carbonic acid 
E)  the data above is useless for this question

Question 6

How is a Lineweaver-Burk plot obtained?​

Accepted Answer

The Lineweaver-Burk double-reciprocal pl

Question 7

All are characteristics of ribozymes EXCEPT:

Accepted Answer

A)  They are critical for removal of introns from mRNA 
B)  They are substrate specific. 
C)  They enhance the reaction rate. 
D)  On the ribosome, they catalyze the peptidyl transferase reaction 
E)  All are true. 
A)  They are critical for removal of introns from mRNA 
B)  They are substrate specific. 
C)  They enhance the reaction rate. 
D)  On the ribosome, they catalyze the peptidyl transferase reaction 
E)  All are true.

Question 8

The catalytically active complex of an apoenzyme and its prosthetic group is referred to a(n) ____.

Accepted Answer

A)  catalytic duo 
B)  holoenzyme 
C)  prosthetic enzyme 
D)  dimeric enzyme 
E)  none of the above 
A)  catalytic duo 
B)  holoenzyme 
C)  prosthetic enzyme 
D)  dimeric enzyme 
E)  none of the above

Question 9

Enzymes work by:

Accepted Answer

A)  providing an alternate reaction pathway 
B)  increasing the spontaneity (ΔG) of the reaction 
C)  lowering the activation energy of the reaction 
D)  altering the concentration of the reactants to achieve a favorable ΔG 
E)  proceeding in only one direction, from reactants to products 
A)  providing an alternate reaction pathway 
B)  increasing the spontaneity (ΔG) of the reaction 
C)  lowering the activation energy of the reaction 
D)  altering the concentration of the reactants to achieve a favorable ΔG 
E)  proceeding in only one direction, from reactants to products

Question 10

Which of the following statements is true regarding enzyme pathways?

Accepted Answer

A)  the most effective way to control a pathway is to regulate every enzyme in the pathway 
B)  an enzyme pathway always proceeds in only one direction, never in reverse 
C)  a regulatory enzyme is regulated only by molecules within the given pathway 
D)  metabolic pathways are necessary since enzymes usually catalyze only one specific reaction 
E)  none of the above are true 
A)  the most effective way to control a pathway is to regulate every enzyme in the pathway 
B)  an enzyme pathway always proceeds in only one direction, never in reverse 
C)  a regulatory enzyme is regulated only by molecules within the given pathway 
D)  metabolic pathways are necessary since enzymes usually catalyze only one specific reaction 
E)  none of the above are true

Exam 13: Enzymeskinetics and Specificity

All of the following statements are true about the relationships between [S], Km and Vmax EXCEPT:

Penicillin is an example of a mechanism-based enzyme inactivator and is a(n):

All are characteristics of ordered single-displacement reactions EXCEPT:

All of the following statements about noncompetitive inhibition are true EXCEPT:

How is a Lineweaver-Burk plot obtained?​

All are characteristics of ribozymes EXCEPT:

The catalytically active complex of an apoenzyme and its prosthetic group is referred to a(n) ____.

Enzymes work by:

Which of the following statements is true regarding enzyme pathways?

The Facts of Life: Chemistry Is the Logic of Biological Phenomena

Water: the Medium of Life

Thermodynamics of Biological Systems

Amino Acids and the Peptide Bond

Proteins: Their Primary Structure and Biological Functions

Proteins: Secondary, Tertiary, and Quaternary Structure

Carbohydrates and the Glycoconjugates of Cell Surfaces

Lipids

Membranes and Membrane Transport

Nucleotides and Nucleic Acids

Structure of Nucleic Acids

Recombinant Dna, Cloning, Chimeric Genes, and Synthetic Biology

Mechanisms of Enzyme Action

Enzyme Regulation

Molecular Motors

Metabolism: an Overview

Glycolysis

The Tricarboxylic Acid Cycle

Electron Transport and Oxidative Phosphorylation

Photosynthesis

Gluconeogenesis, Glycogen Metabolism, and the Pentose Phosphate Pathway

Fatty Acid Catabolism

Lipid Biosynthesis

Nitrogen Acquisition and Amino Acid Metabolism

Synthesis and Degradation of Nucleotides

Metabolic Integration and Organ Specialization

Dna Metabolism: Replication, Recombination, and Repair

Transcription and the Regulation of Gene Expression

Protein Synthesis

Completing the Protein Life Cycle: Folding, Processing, and Degradation

The Reception and Transmission of Extracellular Information

Filters

All of the following statements are true about the relationships between [S], K_m and V_max EXCEPT:

How is a Lineweaver-Burk plot obtained?