BIOL 2083 FINAL EXAM SEMESTER QUESTIONS AND
CORRECT DETAILED ANSWERS (VERIFIED ANSWERS)
ALREADY GRADED A+
Which of the following is true regarding the two models of allostery?
a. in the sequential model, T/R hybrids exist
b. in the concerted model, the R state is less active, but more stable
c. in both models, the T state is more active, but less stable
d. all of the above Ans✓✓✓a. in the sequential model, T/R hybrids exist
Which of the following is true regarding allosteric effectors?
a. allosteric effectors bind to the active site of the enzyme
b. a positive allosteric effector stabilizes the R state of the enzyme
c. a negative allosteric effector pushes the curve toward lower substrate
concentrations for the same activity
d. all of the above Ans✓✓✓b. a positive allosteric effector stabilizes the
R state of the enzyme
The molecule fructose 2,6 bisphosphate binds to the enzyme PFK and
increases its activity at a given substrate concentration. What type of
effector is this molecule?
a. negative effector
b. positive effector
c. not enough information to determine Ans✓✓✓b. positive effector
,Which of the following is true regarding enzymes?
a. allosteric enzymes must have quaternary structure
b. Michaelis-Menton enzymes can have quaternary structure
c. allosteric enzymes bind substrates using noncovalent interactions
d. all of the above Ans✓✓✓d. all of the above
The molecule XSF432 binds only to the enzyme-substrate complex
somewhere other than the active site and prevents turnover. What type
of inhibitor is this molecule?
a. competitive
b. noncompetitive
c. uncompetitive
d. not enough information to determine Ans✓✓✓c. uncompetitive
When comparing kinetic data, the trend line for a Lineweaver-Burk plot
for data measured in the presence of an inhibitor is the same x-intercept
as that of data measured in the absence of the inhibitor, but has a larger
slope. What type of inhibition is occurring?
a. competitive
b. noncompetitive
c. uncompetitive
d. not enough information to determine Ans✓✓✓b. noncompetitive
,You are studying a new enzyme and suspect that a tyrosine residue in
the active site may be critical to its mechanism. What experiment might
give data to support this hypothesis?
a. treat the enzyme with DIPF and see if the tyrosine is modified
b. measure high time resolution kinetics
c. treat the enzyme for a tyrosine-specific group-specific modifier and
see if the residue is modified
d. all of these Ans✓✓✓c. treat the enzyme for a tyrosine-specific group-
specific modifier and see if the residue is modified
Which of the following is true of the mechanism of chymotrypsin?
a. Asp102 forms an oxyanion hole to stabilize the negatively charged
tetrahedral intermediate
b. Asp102 hydrogen bonds with Ser195 in the catalytic triad
c. Ser195 acts as a nucleophile to attack the carbonyl of the peptide
substrate
d. all of the above Ans✓✓✓c. Ser195 acts as a nucleophile to attack the
carbonyl of the peptide substrate
Trypsin is a protease that prefers to cleave peptides close to lysine and
arginine residues. What types of residues do you expect to find in tis SI
binding pocket?
a. hydrophobic residues
b. positively charged residues
c. negatively charged residues Ans✓✓✓c. negatively charged residues
, Which of the following is true of normal, adult hemoglobin?
a. in the deoxy form, the iron atom is within the plane of the heme ring
b. 2,3 bisphosphoglycerate binds to a negatively charged pocket at the
dime-dimer interface
c. only the beta subunits contain heme groups
d. oxygen binds to hemoglobin at the iron atom of the heme ring
Ans✓✓✓d. oxygen binds to hemoglobin at the iron atom of the heme
ring
Which of the following explains why hemoglobin is a better oxygen
delivery molecule than myoglobin?
a myoglobin has low affinity for oxygen at the partial pressure in the
lungs
b. hemoglobin has low affinity for oxygen at the partial pressure in the
lungs
c. hemoglobin binds oxygen with low affinity at partial pressures in the
tissues
d. myoglobin binds oxygen with low affinity at partial pressures in
tissues Ans✓✓✓c. hemoglobin binds oxygen with low affinity at partial
pressures in the tissues
Some diabetic patients experience ketoacidosis that results in a marked
decrease in blood pH. Which of the following describes what is
happening at the molecular level?
CORRECT DETAILED ANSWERS (VERIFIED ANSWERS)
ALREADY GRADED A+
Which of the following is true regarding the two models of allostery?
a. in the sequential model, T/R hybrids exist
b. in the concerted model, the R state is less active, but more stable
c. in both models, the T state is more active, but less stable
d. all of the above Ans✓✓✓a. in the sequential model, T/R hybrids exist
Which of the following is true regarding allosteric effectors?
a. allosteric effectors bind to the active site of the enzyme
b. a positive allosteric effector stabilizes the R state of the enzyme
c. a negative allosteric effector pushes the curve toward lower substrate
concentrations for the same activity
d. all of the above Ans✓✓✓b. a positive allosteric effector stabilizes the
R state of the enzyme
The molecule fructose 2,6 bisphosphate binds to the enzyme PFK and
increases its activity at a given substrate concentration. What type of
effector is this molecule?
a. negative effector
b. positive effector
c. not enough information to determine Ans✓✓✓b. positive effector
,Which of the following is true regarding enzymes?
a. allosteric enzymes must have quaternary structure
b. Michaelis-Menton enzymes can have quaternary structure
c. allosteric enzymes bind substrates using noncovalent interactions
d. all of the above Ans✓✓✓d. all of the above
The molecule XSF432 binds only to the enzyme-substrate complex
somewhere other than the active site and prevents turnover. What type
of inhibitor is this molecule?
a. competitive
b. noncompetitive
c. uncompetitive
d. not enough information to determine Ans✓✓✓c. uncompetitive
When comparing kinetic data, the trend line for a Lineweaver-Burk plot
for data measured in the presence of an inhibitor is the same x-intercept
as that of data measured in the absence of the inhibitor, but has a larger
slope. What type of inhibition is occurring?
a. competitive
b. noncompetitive
c. uncompetitive
d. not enough information to determine Ans✓✓✓b. noncompetitive
,You are studying a new enzyme and suspect that a tyrosine residue in
the active site may be critical to its mechanism. What experiment might
give data to support this hypothesis?
a. treat the enzyme with DIPF and see if the tyrosine is modified
b. measure high time resolution kinetics
c. treat the enzyme for a tyrosine-specific group-specific modifier and
see if the residue is modified
d. all of these Ans✓✓✓c. treat the enzyme for a tyrosine-specific group-
specific modifier and see if the residue is modified
Which of the following is true of the mechanism of chymotrypsin?
a. Asp102 forms an oxyanion hole to stabilize the negatively charged
tetrahedral intermediate
b. Asp102 hydrogen bonds with Ser195 in the catalytic triad
c. Ser195 acts as a nucleophile to attack the carbonyl of the peptide
substrate
d. all of the above Ans✓✓✓c. Ser195 acts as a nucleophile to attack the
carbonyl of the peptide substrate
Trypsin is a protease that prefers to cleave peptides close to lysine and
arginine residues. What types of residues do you expect to find in tis SI
binding pocket?
a. hydrophobic residues
b. positively charged residues
c. negatively charged residues Ans✓✓✓c. negatively charged residues
, Which of the following is true of normal, adult hemoglobin?
a. in the deoxy form, the iron atom is within the plane of the heme ring
b. 2,3 bisphosphoglycerate binds to a negatively charged pocket at the
dime-dimer interface
c. only the beta subunits contain heme groups
d. oxygen binds to hemoglobin at the iron atom of the heme ring
Ans✓✓✓d. oxygen binds to hemoglobin at the iron atom of the heme
ring
Which of the following explains why hemoglobin is a better oxygen
delivery molecule than myoglobin?
a myoglobin has low affinity for oxygen at the partial pressure in the
lungs
b. hemoglobin has low affinity for oxygen at the partial pressure in the
lungs
c. hemoglobin binds oxygen with low affinity at partial pressures in the
tissues
d. myoglobin binds oxygen with low affinity at partial pressures in
tissues Ans✓✓✓c. hemoglobin binds oxygen with low affinity at partial
pressures in the tissues
Some diabetic patients experience ketoacidosis that results in a marked
decrease in blood pH. Which of the following describes what is
happening at the molecular level?
