CMB 311 Practice Questions
With Correct Answers
In the reaction catalyzed by chymotrypsin, a graph in which the rate is
plotted against the concentration of
substrate
a) is sigmoidal, characteristic of an allosteric enzyme
b) shows that cooperative kinetics are observed
c) shows that the reaction is zero order
d) is hyperbolic, characteristic of a nonallosteric enzyme - ANSWER d) is
hyperbolic, characteristic of a nonallosteric enzyme
The initial rate of an enzymatic reaction is usually determined in order to
assure that
a) the enzyme is active
b) there is no reverse reaction of product to the enzyme-substrate complex
c) the substrate is not used up
d) the experiment can be completed quickly - ANSWER b) there is no reverse
reaction of product to the enzyme-substrat
,. According to the steady-state assumption
a) the product concentration does not change significantly
b) the substrate concentration is large and does not change significantly
c) the concentration of enzyme-substrate complex remains constant with
time
d) the free enzyme concentration is always in great excess to the
concentration of enzyme-substrate
complex - ANSWER c) the concentration of enzyme-substrate complex
remains constant with time
. The KM expression is equal to
a) (k1 + k2) / k-1
b) (k-1 + k2) / k1
c) (k1 + k-1) / k2
d) k-1 / k1 - ANSWER b) (k-1 + k2) / k1
Which of the following are related for a given enzyme?
a) V max, KM, and percentage of a-helix
b) V max, k cat, and percentage of b-sheet
c) V max, k cat, and turnover number
d) V max, KM, and molecular weight - ANSWER c) V max, k cat, and turnover
,number
A Lineweaver-Burk plot is useful in the analysis of enzymatic reactions
because
a) it is easier to see whether points deviate from a straight line than from a
curve
b) it is not affected by the presence of inhibitors
c) it can be used whether or not the enzyme displays Michaelis-Menten
kinetics
d) all of the above - ANSWER a) it is easier to see whether points deviate
from a straight line than from a curve
The Lineweaver-Burk graph is easier to use for determining enzyme
parameters than a saturation curve for all the
following reasons, except:
a) It is linear.
b) A computer-graphing program can easily provide the equation for a
straight line.
c) The slope of the graph = Vmax/Km.
d) The x and y intercepts for the straight line provide easy calculation of Km
and Vmax.
e) All of these are correct - ANSWER c) The slope of the graph = Vmax/Km.
, 1. Lipids include the following classes of compounds, except:
a) Fatty acids
b) Steroids
c) Sphingolipids
d) Triacylglycerols
e) All of these are lipids - ANSWER e) All of these are lipids
2. Cerebroside is composed of all of the following, except:
a) Sphingosine
b) Fatty acid
c) Phosphate
d) Sugar
e) All of these can be components of cerebrosides - ANSWER c) Phosphate
3. Unsaturated fatty acids usually have cis double bonds.
a) True
b) False - ANSWER a) True
The products of saponification of a triglyceride include all of these, except:
With Correct Answers
In the reaction catalyzed by chymotrypsin, a graph in which the rate is
plotted against the concentration of
substrate
a) is sigmoidal, characteristic of an allosteric enzyme
b) shows that cooperative kinetics are observed
c) shows that the reaction is zero order
d) is hyperbolic, characteristic of a nonallosteric enzyme - ANSWER d) is
hyperbolic, characteristic of a nonallosteric enzyme
The initial rate of an enzymatic reaction is usually determined in order to
assure that
a) the enzyme is active
b) there is no reverse reaction of product to the enzyme-substrate complex
c) the substrate is not used up
d) the experiment can be completed quickly - ANSWER b) there is no reverse
reaction of product to the enzyme-substrat
,. According to the steady-state assumption
a) the product concentration does not change significantly
b) the substrate concentration is large and does not change significantly
c) the concentration of enzyme-substrate complex remains constant with
time
d) the free enzyme concentration is always in great excess to the
concentration of enzyme-substrate
complex - ANSWER c) the concentration of enzyme-substrate complex
remains constant with time
. The KM expression is equal to
a) (k1 + k2) / k-1
b) (k-1 + k2) / k1
c) (k1 + k-1) / k2
d) k-1 / k1 - ANSWER b) (k-1 + k2) / k1
Which of the following are related for a given enzyme?
a) V max, KM, and percentage of a-helix
b) V max, k cat, and percentage of b-sheet
c) V max, k cat, and turnover number
d) V max, KM, and molecular weight - ANSWER c) V max, k cat, and turnover
,number
A Lineweaver-Burk plot is useful in the analysis of enzymatic reactions
because
a) it is easier to see whether points deviate from a straight line than from a
curve
b) it is not affected by the presence of inhibitors
c) it can be used whether or not the enzyme displays Michaelis-Menten
kinetics
d) all of the above - ANSWER a) it is easier to see whether points deviate
from a straight line than from a curve
The Lineweaver-Burk graph is easier to use for determining enzyme
parameters than a saturation curve for all the
following reasons, except:
a) It is linear.
b) A computer-graphing program can easily provide the equation for a
straight line.
c) The slope of the graph = Vmax/Km.
d) The x and y intercepts for the straight line provide easy calculation of Km
and Vmax.
e) All of these are correct - ANSWER c) The slope of the graph = Vmax/Km.
, 1. Lipids include the following classes of compounds, except:
a) Fatty acids
b) Steroids
c) Sphingolipids
d) Triacylglycerols
e) All of these are lipids - ANSWER e) All of these are lipids
2. Cerebroside is composed of all of the following, except:
a) Sphingosine
b) Fatty acid
c) Phosphate
d) Sugar
e) All of these can be components of cerebrosides - ANSWER c) Phosphate
3. Unsaturated fatty acids usually have cis double bonds.
a) True
b) False - ANSWER a) True
The products of saponification of a triglyceride include all of these, except:
