Biochemistry Quiz Bank (Exam 2)
The relationship between ∆G°' and ∆G is best described as: (Chapter 6) - CORRECT
ANSWERDiffering from standard state to physiological or actual concentrations of
reactants and products
Examples of cofactors include: (Chapter 6) - CORRECT ANSWERZn²⁺, Mg²⁺, Ni²⁺,
biotin, thiamine phosphate, pyridoxal phosphate, coenzyme A
An enzyme will specifically bind its substrate because of: (Chapter 6) - CORRECT
ANSWERA large number of weak interactions at the active site
The Gibbs free energy of activation is: (Chapter 6) - CORRECT ANSWERThe
difference between the substrate and the transition state
A graph of product vs time (Fig 6.2 in book) for an enzyme is determined to be
hyperbolic. Why does the amount of product level off as time increases? (Chapter 6) -
CORRECT ANSWERThe reaction has reached equilibrium. (Forward and reverse
reactions are occuring at a fixed rate.)
At equilibrium, the Gibbs free energy change is: (Chapter 6) - CORRECT ANSWERZero
What must be true of the free energy change (∆G) for a reaction to be spontaneous?
(Chapter 6) - CORRECT ANSWERIt must be negative
A proteolytic enzyme cleaves (Chapter 6) - CORRECT ANSWERPeptide
The alteration of enzyme structure on bind of a substrate to an active site is referred to
as: (Chapter 6) - CORRECT ANSWERInduced fit
In a system at equilibrium: (Chapter 6) - CORRECT ANSWERThere is no net change in
the concentrations of the products and reactants and ∆G is zero
, Catalysis by an enzyme can occur if which of the following happens: (Chapter 6) -
CORRECT ANSWERThe activation energy is decreased in the presence of the enzyme
Which of the following is true under these conditions:
The enzyme concentration is 5 nM, the substrate concentration is 5 mM, and the Km is
5µm? (Chapter 7) - CORRECT ANSWERThe enzyme is saturated with substrate
Allosteric effectors: (Chapter 7) - CORRECT ANSWERCan cause large changes in
enzymatic activity
Allosteric enzymes can be identified because the plot of initial velocity (V0), vs substrate
concentration (S) is not hyperbolic, but _______________ shaped. (Chapter 7) -
CORRECT ANSWERSigmoidal
The y-intercept of the Lineweaver-Burk plot is: (Chapter 7) - CORRECT
ANSWER1/Vmax
What value of [S], as a fraction of Km, is required to obtain 20% Vmax? [S] equals:
(Chapter 7) - CORRECT ANSWER0.25 Km
The Km is: (Chapter 7) - CORRECT ANSWEREqual to the substrate concentration
when the reaction rate is half its maximal value
The type of inhibition by a product of one enzyme on another enzyme in an earlier
protein in a metabolic pathway is considered a(n) ________________ inhibitor.
(Chapter 7) - CORRECT ANSWERFeedback
A critical feature of the Michaelis-Menten model of enzyme catalysis is: (Chapter 7) -
CORRECT ANSWERFormation of an ES complex
Multiple substrate enzyme reactions are divided into two classes: (Chapter 7) -
CORRECT ANSWERSequential displacement and double displacement
An allosteric ______________ stabilizes the T state of the enzyme (Chapter 7) -
CORRECT ANSWERInhibitor
Vmax, the maximum velocity, of an enzyme-catalyzed reaction is: (Chapter 7) -
CORRECT ANSWERThe rate observed when all enzyme active sites are saturated with
substrate
The study of the rates of enzyme-catalyzed reactions: (Chapter 7) - CORRECT
ANSWERIs called enzyme kinetics. Can involve determining how fast the substrate
disappears as it is converted to product. Can involve following the appearance of
product formed over time.
The relationship between ∆G°' and ∆G is best described as: (Chapter 6) - CORRECT
ANSWERDiffering from standard state to physiological or actual concentrations of
reactants and products
Examples of cofactors include: (Chapter 6) - CORRECT ANSWERZn²⁺, Mg²⁺, Ni²⁺,
biotin, thiamine phosphate, pyridoxal phosphate, coenzyme A
An enzyme will specifically bind its substrate because of: (Chapter 6) - CORRECT
ANSWERA large number of weak interactions at the active site
The Gibbs free energy of activation is: (Chapter 6) - CORRECT ANSWERThe
difference between the substrate and the transition state
A graph of product vs time (Fig 6.2 in book) for an enzyme is determined to be
hyperbolic. Why does the amount of product level off as time increases? (Chapter 6) -
CORRECT ANSWERThe reaction has reached equilibrium. (Forward and reverse
reactions are occuring at a fixed rate.)
At equilibrium, the Gibbs free energy change is: (Chapter 6) - CORRECT ANSWERZero
What must be true of the free energy change (∆G) for a reaction to be spontaneous?
(Chapter 6) - CORRECT ANSWERIt must be negative
A proteolytic enzyme cleaves (Chapter 6) - CORRECT ANSWERPeptide
The alteration of enzyme structure on bind of a substrate to an active site is referred to
as: (Chapter 6) - CORRECT ANSWERInduced fit
In a system at equilibrium: (Chapter 6) - CORRECT ANSWERThere is no net change in
the concentrations of the products and reactants and ∆G is zero
, Catalysis by an enzyme can occur if which of the following happens: (Chapter 6) -
CORRECT ANSWERThe activation energy is decreased in the presence of the enzyme
Which of the following is true under these conditions:
The enzyme concentration is 5 nM, the substrate concentration is 5 mM, and the Km is
5µm? (Chapter 7) - CORRECT ANSWERThe enzyme is saturated with substrate
Allosteric effectors: (Chapter 7) - CORRECT ANSWERCan cause large changes in
enzymatic activity
Allosteric enzymes can be identified because the plot of initial velocity (V0), vs substrate
concentration (S) is not hyperbolic, but _______________ shaped. (Chapter 7) -
CORRECT ANSWERSigmoidal
The y-intercept of the Lineweaver-Burk plot is: (Chapter 7) - CORRECT
ANSWER1/Vmax
What value of [S], as a fraction of Km, is required to obtain 20% Vmax? [S] equals:
(Chapter 7) - CORRECT ANSWER0.25 Km
The Km is: (Chapter 7) - CORRECT ANSWEREqual to the substrate concentration
when the reaction rate is half its maximal value
The type of inhibition by a product of one enzyme on another enzyme in an earlier
protein in a metabolic pathway is considered a(n) ________________ inhibitor.
(Chapter 7) - CORRECT ANSWERFeedback
A critical feature of the Michaelis-Menten model of enzyme catalysis is: (Chapter 7) -
CORRECT ANSWERFormation of an ES complex
Multiple substrate enzyme reactions are divided into two classes: (Chapter 7) -
CORRECT ANSWERSequential displacement and double displacement
An allosteric ______________ stabilizes the T state of the enzyme (Chapter 7) -
CORRECT ANSWERInhibitor
Vmax, the maximum velocity, of an enzyme-catalyzed reaction is: (Chapter 7) -
CORRECT ANSWERThe rate observed when all enzyme active sites are saturated with
substrate
The study of the rates of enzyme-catalyzed reactions: (Chapter 7) - CORRECT
ANSWERIs called enzyme kinetics. Can involve determining how fast the substrate
disappears as it is converted to product. Can involve following the appearance of
product formed over time.
