BIOC 384 Exam 2 UPDATED Exam
Questions and CORRECT Answers
Consider the following interaction between a protein and its : [P] + [L] mc021-1.jpg [PL].
If [L] = 5 mM, [P] = 3 mM, and [PL] = 2 mM, what is the dissociation constant? - CORRECT
ANSWER - 7.5 mM
Which of the TWO following statements about x-ray crystallography are true? - CORRECT
ANSWER - Only crystallized proteins can be analyzed.
The x-ray beam is scattered by the protein sample.
A purified protein shows a single band on a native polyacrylamide gel. The band runs toward the
cathode at pH 7. The figure above shows how the same purified protein runs on an SDS
polyacrylamide gel, with or without dithiothreitol (DTT) added to the sample. A marker lane is
included with sizes of MW standards shown in kDa.
Select the TRUE answers from the statements below. - CORRECT ANSWER - The
protein is a heterooligomeric complex of three different polypeptide chains.
The protein probably has a high pI value (>7).
Two subunits of the protein are linked by a disulfide bond.
Which of the following is a genomic caretaker protein? - CORRECT ANSWER -
topoisomerase
Which of the following steps happens first in the oxygen binding process? - CORRECT
ANSWER - The O2 binds to the iron of heme.
Though oxygen only binds to a particular place in the hemoglobin molecule, the oxy- and deoxy-
forms of hemoglobin differ in overall protein conformation. An example of a structural change
that does NOT play a role in translating local binding of oxygen to global protein conformational
change would be the different ______ in the presence and absence of oxygen binding. -
CORRECT ANSWER - location of the distal histidine
,The figure below shows the oxygen binding curve for myoglobin in muscle.
Based on this curve, which of the following is correct? - CORRECT ANSWER - The
lower pO2 in active muscle leads to release of O2 from myoglobin.
Consider five proteins with the properties shown in the table above and answer the following
four questions. Record your answers and choose the set of correct answers for questions a --> d.
a) Which protein would elute first from a (+) charged anion exchange column in buffer at pH
4.0?
b) Which protein would migrate the slowest in an SDS-PAGE gel?
c) Which protein would elute last from a gel filtration chromatography column under non-
denaturing conditions?
d) Which protein would elute last from a (-) charged cation exchange column in buffer at pH 4.0?
- CORRECT ANSWER - A, E, C, A
In isoelectric focusing, a protein that is physically located in the pH gradient that is below the pI
of the protein would: - CORRECT ANSWER - migrate toward the cathode
After centrifugation, there is a 10% decrease in activity and a 75% decrease in total protein.
What is purification of the target protein? - CORRECT ANSWER - 3.6-fold
One of the most difficult steps in X-ray crystallography is: - CORRECT ANSWER -
determining the phases of diffracted x-rays
Biochemical assays are important in the process of isolating proteins because they: - CORRECT
ANSWER - uniquely identify one protein
Below is a fractional saturation curve for O2 binding to adult hemoglobin. Assume that curve Y
represents a system at pH 7.4 and with a normal physiological level of 2,3-BPG. Curve X
represents a system that: - CORRECT ANSWER - has a higher pH with a normal
physiological level of 2,3-BPG
, Which separation technique exploits the solubility differences of proteins? - CORRECT
ANSWER - salting out by ammonium sulfate
The figure below shows three proteins that are separated using gel filtration chromatography.
Which protein is the largest? - CORRECT ANSWER - squares
Which of the following is a positive effector for oxygen binding to hemoglobin? - CORRECT
ANSWER - O2
A polypeptide was digested by trypsin and chymotrypsin. Use the following information to
determine the polypeptide sequence. - CORRECT ANSWER - LMYKWDERMGFCE
The change in free energy for Solute A concentration across a gradient is calculated to be -10
kJ/mol. If Solute B is transported against its own concentration gradient using a secondary active
symporter transport mechanism linked to Solute A, what is the maximum concentration ratio that
can be achieved for Solute B in this system? - CORRECT ANSWER - 50:1
What is the free energy change for transport of a solute from outside the cell to inside the cell
when the concentrations are 5 mM outside and 0.1 mM inside? - CORRECT ANSWER --
10.1 kJ/mol
If the histidine on the F helix (His F8) that coordinates the heme iron that binds to O2 in
hemoglobin is mutated to an alanine, what effect would be most likely? Choose the ONE most
correct answer. - CORRECT ANSWER - Oxygen binding would not cause the movement
of the F helix, since the alanine at F8 cannot coordinate the heme iron.
Which of the following is true of sickle cell anemia? - CORRECT ANSWER - It is cause
by a mutation in the beta-globin gene.
After ______ induced changes in the structure of thin filament, myosin heads containing
__________ in the nucleotide binding site will bind with high affinity to actin subunits. -
CORRECT ANSWER - Ca2+
ADP + Pi
Questions and CORRECT Answers
Consider the following interaction between a protein and its : [P] + [L] mc021-1.jpg [PL].
If [L] = 5 mM, [P] = 3 mM, and [PL] = 2 mM, what is the dissociation constant? - CORRECT
ANSWER - 7.5 mM
Which of the TWO following statements about x-ray crystallography are true? - CORRECT
ANSWER - Only crystallized proteins can be analyzed.
The x-ray beam is scattered by the protein sample.
A purified protein shows a single band on a native polyacrylamide gel. The band runs toward the
cathode at pH 7. The figure above shows how the same purified protein runs on an SDS
polyacrylamide gel, with or without dithiothreitol (DTT) added to the sample. A marker lane is
included with sizes of MW standards shown in kDa.
Select the TRUE answers from the statements below. - CORRECT ANSWER - The
protein is a heterooligomeric complex of three different polypeptide chains.
The protein probably has a high pI value (>7).
Two subunits of the protein are linked by a disulfide bond.
Which of the following is a genomic caretaker protein? - CORRECT ANSWER -
topoisomerase
Which of the following steps happens first in the oxygen binding process? - CORRECT
ANSWER - The O2 binds to the iron of heme.
Though oxygen only binds to a particular place in the hemoglobin molecule, the oxy- and deoxy-
forms of hemoglobin differ in overall protein conformation. An example of a structural change
that does NOT play a role in translating local binding of oxygen to global protein conformational
change would be the different ______ in the presence and absence of oxygen binding. -
CORRECT ANSWER - location of the distal histidine
,The figure below shows the oxygen binding curve for myoglobin in muscle.
Based on this curve, which of the following is correct? - CORRECT ANSWER - The
lower pO2 in active muscle leads to release of O2 from myoglobin.
Consider five proteins with the properties shown in the table above and answer the following
four questions. Record your answers and choose the set of correct answers for questions a --> d.
a) Which protein would elute first from a (+) charged anion exchange column in buffer at pH
4.0?
b) Which protein would migrate the slowest in an SDS-PAGE gel?
c) Which protein would elute last from a gel filtration chromatography column under non-
denaturing conditions?
d) Which protein would elute last from a (-) charged cation exchange column in buffer at pH 4.0?
- CORRECT ANSWER - A, E, C, A
In isoelectric focusing, a protein that is physically located in the pH gradient that is below the pI
of the protein would: - CORRECT ANSWER - migrate toward the cathode
After centrifugation, there is a 10% decrease in activity and a 75% decrease in total protein.
What is purification of the target protein? - CORRECT ANSWER - 3.6-fold
One of the most difficult steps in X-ray crystallography is: - CORRECT ANSWER -
determining the phases of diffracted x-rays
Biochemical assays are important in the process of isolating proteins because they: - CORRECT
ANSWER - uniquely identify one protein
Below is a fractional saturation curve for O2 binding to adult hemoglobin. Assume that curve Y
represents a system at pH 7.4 and with a normal physiological level of 2,3-BPG. Curve X
represents a system that: - CORRECT ANSWER - has a higher pH with a normal
physiological level of 2,3-BPG
, Which separation technique exploits the solubility differences of proteins? - CORRECT
ANSWER - salting out by ammonium sulfate
The figure below shows three proteins that are separated using gel filtration chromatography.
Which protein is the largest? - CORRECT ANSWER - squares
Which of the following is a positive effector for oxygen binding to hemoglobin? - CORRECT
ANSWER - O2
A polypeptide was digested by trypsin and chymotrypsin. Use the following information to
determine the polypeptide sequence. - CORRECT ANSWER - LMYKWDERMGFCE
The change in free energy for Solute A concentration across a gradient is calculated to be -10
kJ/mol. If Solute B is transported against its own concentration gradient using a secondary active
symporter transport mechanism linked to Solute A, what is the maximum concentration ratio that
can be achieved for Solute B in this system? - CORRECT ANSWER - 50:1
What is the free energy change for transport of a solute from outside the cell to inside the cell
when the concentrations are 5 mM outside and 0.1 mM inside? - CORRECT ANSWER --
10.1 kJ/mol
If the histidine on the F helix (His F8) that coordinates the heme iron that binds to O2 in
hemoglobin is mutated to an alanine, what effect would be most likely? Choose the ONE most
correct answer. - CORRECT ANSWER - Oxygen binding would not cause the movement
of the F helix, since the alanine at F8 cannot coordinate the heme iron.
Which of the following is true of sickle cell anemia? - CORRECT ANSWER - It is cause
by a mutation in the beta-globin gene.
After ______ induced changes in the structure of thin filament, myosin heads containing
__________ in the nucleotide binding site will bind with high affinity to actin subunits. -
CORRECT ANSWER - Ca2+
ADP + Pi
