BCH 367 CH 6 QUESTIONS AND
ANSWERS (GRADED A+)
Which of the following is true of a holoenzyme but not an apoenzyme?
a) contains a cofactor
b) is catalytically inactive
c) contains a denatured active site
d) contains more than one active site
e) is both catalytically inactive and contains a denatured active site - ANSWER-a
An enzyme cannot alter the laws of thermodynamics and consequently cannot alter the
_____ of a chemical reaction. - ANSWER-equilibrium
The essence of catalysis is stabilization of the _____. - ANSWER-transition state
A reaction must have a very slow uncatalyzed rate in order to have a:
a) fast rate enhancement.
b) fast catalyzed rate.
c) long nonenzymatic half-life.
d) negative Δ G. - ANSWER-c
If a reaction has a ΔG that is positive, it is a(n) _____ reaction. - ANSWER-endergonic
Which class of enzyme adds atoms or functional groups to a double bond?
a) transferases
b) lyases
c) oxidoreductases
d) ligases
e) isomerases - ANSWER-b
ΔG‡ is the _____ of a reaction. - ANSWER-free energy of activation
If you were to design a transition-state analog that would act as an inhibitor of trypsin,
which of the following may you include in the design?
a) a geometry equivalent to the substrates of trypsin
b) a geometry equivalent to the products of trypsin
c) a charge equivalent to that found in the transition state of the reaction catalyzed
d) a charge equivalent to that found in the substrates of trypsin - ANSWER-c
, In a system at equilibrium:
a) there is no net change in the concentrations of the products and reactants.
b) ΔG is zero.
c) ΔG‡ is zero.
d) there is no net change in the concentrations of the products and reactants and ΔG is
zero.
e) there is no net change in the concentrations of the products and ΔG‡ is zero. -
ANSWER-d
Which of the following is another way to write activation energy?
a) X‡
b) ΔG
c) ΔG‡ - ANSWER-c
The precision of the interaction between an enzyme and substrate is due to the intricate
three-dimensional structure of the enzyme. This is known as substrate _____. -
ANSWER-specificity
Calculate the ΔG°′ for a reaction of A→B that has a K′eq of 0.082.
a) 6.22 kJ mol—1
b) —6.22 kJ mol—1
c) —0.519 kJ mol—1
d 6.22 kcal mol—1 - ANSWER-a
Enzymes alter the _____ but do not alter the _____.
a) ΔG; ΔG‡
b) reaction equilibrium; reaction rate
c) reaction rate; reaction equilibrium - ANSWER-c
Antibodies have been generated that recognize the transition states of certain reactions.
These antibodies are called catalytic antibodies or _____ and can function as enzymes.
- ANSWER-abzymes
Which of the following statements is INCORRECT?
a) The ΔG of a reaction is dependent on the path of transformation.
b) The ΔG provides information about the rate of a reaction.
c) A reaction can take place spontaneously only if ΔG is negative.
d) Both first and second answer - ANSWER-d
Small organici molecules, derived from vitamins, that are enzyme cofactors are also
called _____. - ANSWER-coenzymes
ANSWERS (GRADED A+)
Which of the following is true of a holoenzyme but not an apoenzyme?
a) contains a cofactor
b) is catalytically inactive
c) contains a denatured active site
d) contains more than one active site
e) is both catalytically inactive and contains a denatured active site - ANSWER-a
An enzyme cannot alter the laws of thermodynamics and consequently cannot alter the
_____ of a chemical reaction. - ANSWER-equilibrium
The essence of catalysis is stabilization of the _____. - ANSWER-transition state
A reaction must have a very slow uncatalyzed rate in order to have a:
a) fast rate enhancement.
b) fast catalyzed rate.
c) long nonenzymatic half-life.
d) negative Δ G. - ANSWER-c
If a reaction has a ΔG that is positive, it is a(n) _____ reaction. - ANSWER-endergonic
Which class of enzyme adds atoms or functional groups to a double bond?
a) transferases
b) lyases
c) oxidoreductases
d) ligases
e) isomerases - ANSWER-b
ΔG‡ is the _____ of a reaction. - ANSWER-free energy of activation
If you were to design a transition-state analog that would act as an inhibitor of trypsin,
which of the following may you include in the design?
a) a geometry equivalent to the substrates of trypsin
b) a geometry equivalent to the products of trypsin
c) a charge equivalent to that found in the transition state of the reaction catalyzed
d) a charge equivalent to that found in the substrates of trypsin - ANSWER-c
, In a system at equilibrium:
a) there is no net change in the concentrations of the products and reactants.
b) ΔG is zero.
c) ΔG‡ is zero.
d) there is no net change in the concentrations of the products and reactants and ΔG is
zero.
e) there is no net change in the concentrations of the products and ΔG‡ is zero. -
ANSWER-d
Which of the following is another way to write activation energy?
a) X‡
b) ΔG
c) ΔG‡ - ANSWER-c
The precision of the interaction between an enzyme and substrate is due to the intricate
three-dimensional structure of the enzyme. This is known as substrate _____. -
ANSWER-specificity
Calculate the ΔG°′ for a reaction of A→B that has a K′eq of 0.082.
a) 6.22 kJ mol—1
b) —6.22 kJ mol—1
c) —0.519 kJ mol—1
d 6.22 kcal mol—1 - ANSWER-a
Enzymes alter the _____ but do not alter the _____.
a) ΔG; ΔG‡
b) reaction equilibrium; reaction rate
c) reaction rate; reaction equilibrium - ANSWER-c
Antibodies have been generated that recognize the transition states of certain reactions.
These antibodies are called catalytic antibodies or _____ and can function as enzymes.
- ANSWER-abzymes
Which of the following statements is INCORRECT?
a) The ΔG of a reaction is dependent on the path of transformation.
b) The ΔG provides information about the rate of a reaction.
c) A reaction can take place spontaneously only if ΔG is negative.
d) Both first and second answer - ANSWER-d
Small organici molecules, derived from vitamins, that are enzyme cofactors are also
called _____. - ANSWER-coenzymes
