1|Page
BIOC 384 TEST EXAM 2|| QUESTIONS AND 100%
CORRECT ANSWERS ALREADY GRADED A+||
LATEST AND COMPLETE UPDATE WITH
VERIFIED SOLUTIONS GUARANTEED PASS!!!
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? -
ANSWER: 7.5 mM
Which of the TWO following statements about x-ray crystallography are true? -
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. - 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? - ANSWER:
topoisomerase
Which of the following steps happens first in the oxygen binding process? -
ANSWER: The O2 binds to the iron of heme.
,2|Page
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. - 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? - 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? - 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: - 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? - ANSWER: 3.6-fold
, 3|Page
One of the most difficult steps in X-ray crystallography is: - ANSWER:
determining the phases of diffracted x-rays
Biochemical assays are important in the process of isolating proteins because they:
- 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: - ANSWER: has a higher pH with a
normal physiological level of 2,3-BPG
Which separation technique exploits the solubility differences of proteins? -
ANSWER: salting out by ammonium sulfate
The figure below shows three proteins that are separated using gel filtration
chromatography. Which protein is the largest? - ANSWER: squares
Which of the following is a positive effector for oxygen binding to hemoglobin? -
ANSWER: O2
A polypeptide was digested by trypsin and chymotrypsin. Use the following
information to determine the polypeptide sequence. - 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? - ANSWER: 50:1
BIOC 384 TEST EXAM 2|| QUESTIONS AND 100%
CORRECT ANSWERS ALREADY GRADED A+||
LATEST AND COMPLETE UPDATE WITH
VERIFIED SOLUTIONS GUARANTEED PASS!!!
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? -
ANSWER: 7.5 mM
Which of the TWO following statements about x-ray crystallography are true? -
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. - 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? - ANSWER:
topoisomerase
Which of the following steps happens first in the oxygen binding process? -
ANSWER: The O2 binds to the iron of heme.
,2|Page
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. - 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? - 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? - 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: - 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? - ANSWER: 3.6-fold
, 3|Page
One of the most difficult steps in X-ray crystallography is: - ANSWER:
determining the phases of diffracted x-rays
Biochemical assays are important in the process of isolating proteins because they:
- 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: - ANSWER: has a higher pH with a
normal physiological level of 2,3-BPG
Which separation technique exploits the solubility differences of proteins? -
ANSWER: salting out by ammonium sulfate
The figure below shows three proteins that are separated using gel filtration
chromatography. Which protein is the largest? - ANSWER: squares
Which of the following is a positive effector for oxygen binding to hemoglobin? -
ANSWER: O2
A polypeptide was digested by trypsin and chymotrypsin. Use the following
information to determine the polypeptide sequence. - 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? - ANSWER: 50:1
