BCH 367 CH 7 WITH COMPLETE
QUESTIONS AND ANSWERS (GRADED
A+)
When an enzyme is operating at Vmax, the enzyme:
a) displays zero-order kinetics.
b) displays second-order kinetics.
c) displays pseudo—first-order kinetics.
d) displays kinetics dependent upon the number of reactants specific to that enzyme
system.
e) displays first-order kinetics. - ANSWER-a
Enzymes that follow simple Michaelis-Menten kinetics are called Michaelis-Menten
enzymes. Alternatively, enzymes that regulate the flux of biochemical through metabolic
pathways are called _____ enzymes. - ANSWER-allosteric
Which of the following is a CORRECT unit for a second-order rate constant?
a) M/s
b)M_1
c)M_1 s_1
d)M/s_1
e) M - ANSWER-c
The enzyme trypsin prefers to cleave peptide substrates following a positively charged
amino acid. An experiment is carried out in which the kinetics of trypsin are measured
using the different substrates shown below. Which answer is CORRECT?
Substrate #1: Phe-Gly-Leu-Lys-Ala-Ala
Substrate #2: Phe-Gly-Leu-Ala-Ala-Ala
Substrate #3: Phe-Gly-Leu-Asp-Ala-Ala
a) Kcat/KM is the same for all three substrates.
b) Kcat/KM is highest for substrate #1.
c) Kcat/KM is highest for substrate #2.
d) Kcat/KM is highest for substrate #3. - ANSWER-b
Allosteric sites:
a) are also called regulatory sites.
b) bind compounds that are structurally different from the substrate.
, c) are the locations where allosteric effectors bind to the enzyme.
d) All - ANSWER-d
An in singulo method:
a) requires that the experiment be carried out only one time.
b) examines one individual at a time.
c) is a subtype of ensemble study.
d) provides information on first-order reactions, but not second-order reactions. -
ANSWER-b
In an allosteric enzyme system, as the concentration of an allosteric inhibitor increases:
a) L0 increases.
b) L0 decreases.
c) Vmax increases
d) both L0 and Vmax increase.
e) L0 decreases and Vmax increases. - ANSWER-a
Allosteric enzymes are _____, where _____ at one site _____.
a) isozymes; the activity; is different from the activity at a different site
b) isozymes; activity; affects the activity at a different site
c) cooperative; proteolytic cleavage; increases the activity of the enzyme
d) cooperative; activity; affects the activity at a different site
e) cooperative; inhibition; increases the ability of another site to bind substrate. -
ANSWER-d
The Michaelis constant, KM:
a) is equal to ½Vmax.
b) is equal to the velocity of the reaction when the enzyme is 50% saturated with
substrate.
c) is equal to the substrate concentration when the velocity of the reaction is 50% of the
maximum velocity.
d) is equal to the rate constant, k, when the reaction is in the steady state. - ANSWER-c
Which of the following statements about allosteric enzymes is true?
a) Allosteric enzymes follow Michaelis-Menten kinetics.
b) Allosteric enzymes can exist in an R state, which has a low affinity for substrate.
c) Allosteric enzymes have quaternary structure.
d) Allosteric enzymes capture the binding energy of the substrate to catalyze otherwise
thermodynamically unfavorable reactions. - ANSWER-c
In a pseudo —first-order reaction:
QUESTIONS AND ANSWERS (GRADED
A+)
When an enzyme is operating at Vmax, the enzyme:
a) displays zero-order kinetics.
b) displays second-order kinetics.
c) displays pseudo—first-order kinetics.
d) displays kinetics dependent upon the number of reactants specific to that enzyme
system.
e) displays first-order kinetics. - ANSWER-a
Enzymes that follow simple Michaelis-Menten kinetics are called Michaelis-Menten
enzymes. Alternatively, enzymes that regulate the flux of biochemical through metabolic
pathways are called _____ enzymes. - ANSWER-allosteric
Which of the following is a CORRECT unit for a second-order rate constant?
a) M/s
b)M_1
c)M_1 s_1
d)M/s_1
e) M - ANSWER-c
The enzyme trypsin prefers to cleave peptide substrates following a positively charged
amino acid. An experiment is carried out in which the kinetics of trypsin are measured
using the different substrates shown below. Which answer is CORRECT?
Substrate #1: Phe-Gly-Leu-Lys-Ala-Ala
Substrate #2: Phe-Gly-Leu-Ala-Ala-Ala
Substrate #3: Phe-Gly-Leu-Asp-Ala-Ala
a) Kcat/KM is the same for all three substrates.
b) Kcat/KM is highest for substrate #1.
c) Kcat/KM is highest for substrate #2.
d) Kcat/KM is highest for substrate #3. - ANSWER-b
Allosteric sites:
a) are also called regulatory sites.
b) bind compounds that are structurally different from the substrate.
, c) are the locations where allosteric effectors bind to the enzyme.
d) All - ANSWER-d
An in singulo method:
a) requires that the experiment be carried out only one time.
b) examines one individual at a time.
c) is a subtype of ensemble study.
d) provides information on first-order reactions, but not second-order reactions. -
ANSWER-b
In an allosteric enzyme system, as the concentration of an allosteric inhibitor increases:
a) L0 increases.
b) L0 decreases.
c) Vmax increases
d) both L0 and Vmax increase.
e) L0 decreases and Vmax increases. - ANSWER-a
Allosteric enzymes are _____, where _____ at one site _____.
a) isozymes; the activity; is different from the activity at a different site
b) isozymes; activity; affects the activity at a different site
c) cooperative; proteolytic cleavage; increases the activity of the enzyme
d) cooperative; activity; affects the activity at a different site
e) cooperative; inhibition; increases the ability of another site to bind substrate. -
ANSWER-d
The Michaelis constant, KM:
a) is equal to ½Vmax.
b) is equal to the velocity of the reaction when the enzyme is 50% saturated with
substrate.
c) is equal to the substrate concentration when the velocity of the reaction is 50% of the
maximum velocity.
d) is equal to the rate constant, k, when the reaction is in the steady state. - ANSWER-c
Which of the following statements about allosteric enzymes is true?
a) Allosteric enzymes follow Michaelis-Menten kinetics.
b) Allosteric enzymes can exist in an R state, which has a low affinity for substrate.
c) Allosteric enzymes have quaternary structure.
d) Allosteric enzymes capture the binding energy of the substrate to catalyze otherwise
thermodynamically unfavorable reactions. - ANSWER-c
In a pseudo —first-order reaction:
