BIOC 384 EXAM 2 Question and
answer verified to pass 2025/2026
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
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.
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? - correct answer ✔7.5
mM
Which separation technique exploits the solubility differences of proteins? - correct answer ✔salting
out by ammonium sulfate
Which of the following is a positive effector for oxygen binding to hemoglobin? - correct answer ✔O2
One of the most difficult steps in X-ray crystallography is - correct answer ✔determining the phases of
diffracted X-rays.
A polypeptide was digested by trypsin and chymotrypsin. Use the following information to determine
the polypeptide sequence.
Trypsin Digest Chymotrypsin Digest
LMYK CE
,MGFCE LMYKW
WDER DERMGF - correct answer ✔LMYKWDERMGFCE
Biochemical assays are important in the process of isolating proteins because they - correct answer
✔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 - correct answer ✔migrate toward the cathode.
The figure below shows three proteins that are separated using gel filtration chromatography. Which
protein is the largest? - correct answer ✔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. -
correct answer ✔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. - correct answer ✔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.
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 - correct answer ✔4, 1, 5, 3, 2
Which statement most accurately describes the structure and function of O2 transport proteins. -
correct answer ✔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)? - correct answer ✔1. A
2. A
3. B
4. A
5. B
6. A
In one type of hemoglobin mutant the amino acid change eliminates a hydrogen bond that
normally stabilizes the R state. Would you expect this mutant hemoglobin to have a higher or lower O2
affinity compared to the normal protein and why? - correct answer ✔Lower O2 affinity because the R-T
equilibrium would be mostly shifted to the T state.
answer verified to pass 2025/2026
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
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.
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? - correct answer ✔7.5
mM
Which separation technique exploits the solubility differences of proteins? - correct answer ✔salting
out by ammonium sulfate
Which of the following is a positive effector for oxygen binding to hemoglobin? - correct answer ✔O2
One of the most difficult steps in X-ray crystallography is - correct answer ✔determining the phases of
diffracted X-rays.
A polypeptide was digested by trypsin and chymotrypsin. Use the following information to determine
the polypeptide sequence.
Trypsin Digest Chymotrypsin Digest
LMYK CE
,MGFCE LMYKW
WDER DERMGF - correct answer ✔LMYKWDERMGFCE
Biochemical assays are important in the process of isolating proteins because they - correct answer
✔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 - correct answer ✔migrate toward the cathode.
The figure below shows three proteins that are separated using gel filtration chromatography. Which
protein is the largest? - correct answer ✔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. -
correct answer ✔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. - correct answer ✔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.
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 - correct answer ✔4, 1, 5, 3, 2
Which statement most accurately describes the structure and function of O2 transport proteins. -
correct answer ✔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)? - correct answer ✔1. A
2. A
3. B
4. A
5. B
6. A
In one type of hemoglobin mutant the amino acid change eliminates a hydrogen bond that
normally stabilizes the R state. Would you expect this mutant hemoglobin to have a higher or lower O2
affinity compared to the normal protein and why? - correct answer ✔Lower O2 affinity because the R-T
equilibrium would be mostly shifted to the T state.
