BIOCHEM 384
BIOC 384 EXAM 2 QUESTIONS AND
ANSWERS GRADED A
After centrifugation, there is a 10% decrease in activity and a 75% decrease in total
protein. What is purification of the target protein? - 3.6-Fold
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 - has a higher pH with a normal physiological level of
2,3-BPG.
Consider the following interaction between a protein and its ligand: [P] + [L] mc021-
1.jpg [PL].
If [L] = 5 mM, [P] = 3 mM, and [PL] = 2 mM, what is the dissociation constant? - 7.5
mM
Which separation technique exploits the solubility differences of proteins? - salting out
by ammonium sulfate
Which of the following is a positive effector for oxygen binding to hemoglobin? - O2
One of the most difficult steps in X-ray crystallography is - determining the phases of
diffracted X-rays.
A polypeptide was digested by trypsin and chymotrypsin. Use the following information
to determine the polypeptide sequence.
BIOCHEM 384
,BIOCHEM 384
Trypsin Digest Chymotrypsin Digest
LMYK CE
MGFCE LMYKW
WDER DERMGF - LMYKWDERMGFCE
Biochemical assays are important in the process of isolating proteins because they -
uniquely identify one protein.
In isoelectric focusing, a protein that is physically located in the pH gradient that is below
the pI of the protein would - migrate toward the cathode.
The figure below shows three proteins that are separated using gel filtration
chromatography. Which protein is the largest? - squares
X-ray crystallography (XRC) and nuclear magnetic resonance (NMR) spectroscopy
provide three dimensional structural information about the position of atoms in a purified
protein. Name one advantage
(adv) and one disadvantage (dvg) of each technique with regard to high resolution protein
structures. - XRC/adv;; large proteins, XRC/dvg;; requires crystals, NMR/adv;; soluble
protein, NMR/dvg;; small proteins
Protein-specific antibodies are useful experimental tools in biochemistry. Choose the one
statement below that most correctly describes these biochemical reagents. - Polyclonal
antibodies are a heterogeneous mixture of antibodies that recognize epitopes on an
antigen.
Match each representative protein with the most correct specific major protein functional
class.
BIOCHEM 384
, BIOCHEM 384
Record your answer in the order of a, b, c, d, and e, by choosing the numbers 1, 2, 3, 4,
and 5.
Major Protein Class Representative Protein
a. Cell signaling 1. Malate dehydrogenase
b. Metabolic enzyme 2. Na+/K+ ATPase
c. Genomic caretaker 3. Tubulin
d. Structural protein 4. G protein-coupled
receptor
Transport protein 5. RNA polymerase - 4, 1, 5, 3, 2
Which statement most accurately describes the structure and function of O2 transport
proteins. - Hemoglobin is a tetramer that can bind BPG and O2 whereas myoglobin binds
O2 but cannot bind BPG.
Answer the following questions about the graph shown at the right.
1. The protein with the lowest dissociation constant (Kd) is protein (A or B)?
2. The protein with the highest affinity for oxygen is protein (A or B)?
3. The protein most likely to bind oxygen cooperatively is protein (A or B)?
4. The protein most likely to be an oxygen storage protein is protein (A or B)?
5. The protein most likely to be hemoglobin is protein (A or B)?
6. The protein most likely to be myoglobin is protein (A or B)? - 1. A
2. A
3. B
4. A
BIOCHEM 384
BIOC 384 EXAM 2 QUESTIONS AND
ANSWERS GRADED A
After centrifugation, there is a 10% decrease in activity and a 75% decrease in total
protein. What is purification of the target protein? - 3.6-Fold
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 - has a higher pH with a normal physiological level of
2,3-BPG.
Consider the following interaction between a protein and its ligand: [P] + [L] mc021-
1.jpg [PL].
If [L] = 5 mM, [P] = 3 mM, and [PL] = 2 mM, what is the dissociation constant? - 7.5
mM
Which separation technique exploits the solubility differences of proteins? - salting out
by ammonium sulfate
Which of the following is a positive effector for oxygen binding to hemoglobin? - O2
One of the most difficult steps in X-ray crystallography is - determining the phases of
diffracted X-rays.
A polypeptide was digested by trypsin and chymotrypsin. Use the following information
to determine the polypeptide sequence.
BIOCHEM 384
,BIOCHEM 384
Trypsin Digest Chymotrypsin Digest
LMYK CE
MGFCE LMYKW
WDER DERMGF - LMYKWDERMGFCE
Biochemical assays are important in the process of isolating proteins because they -
uniquely identify one protein.
In isoelectric focusing, a protein that is physically located in the pH gradient that is below
the pI of the protein would - migrate toward the cathode.
The figure below shows three proteins that are separated using gel filtration
chromatography. Which protein is the largest? - squares
X-ray crystallography (XRC) and nuclear magnetic resonance (NMR) spectroscopy
provide three dimensional structural information about the position of atoms in a purified
protein. Name one advantage
(adv) and one disadvantage (dvg) of each technique with regard to high resolution protein
structures. - XRC/adv;; large proteins, XRC/dvg;; requires crystals, NMR/adv;; soluble
protein, NMR/dvg;; small proteins
Protein-specific antibodies are useful experimental tools in biochemistry. Choose the one
statement below that most correctly describes these biochemical reagents. - Polyclonal
antibodies are a heterogeneous mixture of antibodies that recognize epitopes on an
antigen.
Match each representative protein with the most correct specific major protein functional
class.
BIOCHEM 384
, BIOCHEM 384
Record your answer in the order of a, b, c, d, and e, by choosing the numbers 1, 2, 3, 4,
and 5.
Major Protein Class Representative Protein
a. Cell signaling 1. Malate dehydrogenase
b. Metabolic enzyme 2. Na+/K+ ATPase
c. Genomic caretaker 3. Tubulin
d. Structural protein 4. G protein-coupled
receptor
Transport protein 5. RNA polymerase - 4, 1, 5, 3, 2
Which statement most accurately describes the structure and function of O2 transport
proteins. - Hemoglobin is a tetramer that can bind BPG and O2 whereas myoglobin binds
O2 but cannot bind BPG.
Answer the following questions about the graph shown at the right.
1. The protein with the lowest dissociation constant (Kd) is protein (A or B)?
2. The protein with the highest affinity for oxygen is protein (A or B)?
3. The protein most likely to bind oxygen cooperatively is protein (A or B)?
4. The protein most likely to be an oxygen storage protein is protein (A or B)?
5. The protein most likely to be hemoglobin is protein (A or B)?
6. The protein most likely to be myoglobin is protein (A or B)? - 1. A
2. A
3. B
4. A
BIOCHEM 384
