BIOC 384 Exam 2 UPDATED ACTUAL
Exam Questions and CORRECT Answers
Although most protein sequencing is now done by mass spectrometry (MS), Edman degradation
(ED) is useful if large amounts of a protein can be obtained even if from an uncharacterized
species. Answer the True/False questions regarding methods used to sequence a polypeptide
fragment: - CORRECT ANSWER - False - The N-terminal residue removed by acid
treatment in ED is always a methionine.
False - Trypsin and chymotrypsin treatment often provides identical peptide fragments for ED
True - Genomic sequences are needed to predict protein sequences by the MS method.
True - Trypsin treatment provides useful sequence information when analyzing data from MS.
False - Protein sequencing by ED does not require purified protein but sequencing by MS does
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. -
CORRECT ANSWER - Cell signaling: G Protein-coupled receptor
Metabolic Enzyme: Malate dehydrogenase
Genomic Caretaker: RNA polymerase
Structural Protein: Tubulin
Transport Protein: Na+/K+ ATPase
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) protein A (2) protein A (3) protein B (4) protein A (5) protein B (6) protein A
*Refer to image
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.
Exam Questions and CORRECT Answers
Although most protein sequencing is now done by mass spectrometry (MS), Edman degradation
(ED) is useful if large amounts of a protein can be obtained even if from an uncharacterized
species. Answer the True/False questions regarding methods used to sequence a polypeptide
fragment: - CORRECT ANSWER - False - The N-terminal residue removed by acid
treatment in ED is always a methionine.
False - Trypsin and chymotrypsin treatment often provides identical peptide fragments for ED
True - Genomic sequences are needed to predict protein sequences by the MS method.
True - Trypsin treatment provides useful sequence information when analyzing data from MS.
False - Protein sequencing by ED does not require purified protein but sequencing by MS does
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. -
CORRECT ANSWER - Cell signaling: G Protein-coupled receptor
Metabolic Enzyme: Malate dehydrogenase
Genomic Caretaker: RNA polymerase
Structural Protein: Tubulin
Transport Protein: Na+/K+ ATPase
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) protein A (2) protein A (3) protein B (4) protein A (5) protein B (6) protein A
*Refer to image
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.
