54.
Which of the following is a correct bond-line structure for a tripeptide Ser-Lys-Cys?
H2N
H
N
N
H
OH
O
O
OS
HO SH
H2N
H
N
N
H
OH
O
O
OS
HO SH
H2N
H
N
N
H
OH
(CH2)4NH2
O
O
O
HO SH
H2N
H
N
N
H
OH
(CH2)4NH2
O
O
O
HS OH
III
III IV
A)
I
B)
II
C)
III
D)
IV
E)
none of these
55.
Draw a bond-line structure for the tetrapetide Ala-Ser-Cys-Phe.
Ans:
A
56.
Draw a bond-line structure for the tetrapetide Ile-Ser-Leu-Gly.
57.
What is the correct sequence of amino acids for the following tripeptide?
H2N
H
N
N
H
OH
O
O
OS
HO
A)
Ser-Met-Ile
B)
Ser-Cys-Ile
C)
Thr-Met-Leu
D)
Thr-Cys-Leu
E)
none of these
Ans:
C
58.
What is the correct sequence of amino acids for the following tripeptide?
H2N
H
N
N
H
OH
O
O
O
A)
Leu-Phe-Ala
B)
Val-Phe-Ala
C)
Ile-Tyr-Leu
D)
Leu-Tyr-Val
E)
none of these
59.
What is the three letter abbreviation for the sequencing of the following peptide?
H2N
H
N
N
H
H
N
O
O
O
N
H
H
N
O
O
OH
O
OH
OH
Ans:
Ile-Tyr-Ser-Val-Ala-Phe
60.
The s-trans conformation of a peptide bond is more stable than the s-cis conformation
because:
A)
there is a restricted rotation around the peptide bond
B)
rotation is allowed around the peptide bond
C)
it has reduced steric hindrance
D)
none of these
Ans:
C
Ans:
B
61.
Disulfide bridges are formed by:
A)
oxidation of thiol groups
B)
joining cysteine residues within a peptide
C)
joining cysteine residues between two strands of a peptide
D)
all of these
62.
Which of the following reagent(s) is(are) used to remove the N-terminus amino acid
residue using Edman degradation?
N
C
N
II
N
C
S
N
C
ONH
O
Ph
O
R
I III
A)
I
B)
II
C)
III
D)
IV
E)
none of these
Ans:
A
63.
Edman degradation removes the amino acid residue from the _______ of the peptide.
A)
C-terminus end
B)
N-terminus end
C)
middle end
D)
none of these
Ans:
B
Ans:
D
64.
Which of the following results after single Edman degradation of the tetrapeptide Gly-
Phe-Tyr-Ser?
A)
Gly-Phe-Tyr
B)
Tyr-Ser
C)
Phe-Tyr-Ser
D)
Gly-Phe
E)
none of these
65.
Which of the following results after three steps of Edman degradation of the
heptapeptide Lys-His-Gly-Phe-Tyr-Ser-Ala?
A)
Lys-His-Gly
B)
Phe-Tyr-Ser-Ala
C)
Tyr-Ser-Ala
D)
Lys-His-Gly-Phe
E)
none of these
Ans:
B
66.
Chymotrypsin, a digestive enzyme, catalyzes the hydrolysis of the peptide bond at the
carboxyl end of which of the following amino acids?
H2N CH C
CH2
OH
O
N
NH
H2N CH C
CH2
OH
O
HN
histidine
tryptophan
H2N CH C
CH2
OH
O
H2N CH C
CH2
OH
O
OH
phenyalanine tyrosine
A)
phenylalanine
B)
tyrosine
C)
tryptophan
D)
histidine
E)
A, B & C
Ans:
E
Ans:
C
67.
Trypsin, a digestive enzyme, catalyzes the hydrolysis of the peptide bond at the
carboxyl end of which of the following amino acids?
H2N CH C
CH2
OH
O
CH2
CH2
NH
C
NH2
NH
H2N CH C
CH2
OH
O
CH2
CH2
CH2
NH2
H2N CH C
CH2
OH
O
N
NH
H2N CH C
CH2
OH
O
HN
arginine
lysine
histidine tryptophan
A)
arginine
B)
lysine
C)
histidine
D)
tryptophan
E)
A & B
Ans:
E
68.
Which of the following tetrapeptides is not cleaved by trypsin?
A)
Gly-Lys-Cys-Phe
B)
Cys-Ala-Arg-Ser
C)
Gly-Ser-Ile-Lys
D)
Ala-Lys-Tyr-Arg
E)
none of these
Ans:
C
69.
Which of the following tetrapeptides is not cleaved by chymotrypsin?
A)
Gly-Lys-Cys-Trp
B)
Cys-Tyr-Arg-Phe
C)
Phe-Ser-Ile-Lys
D)
Ala-Trp-Tyr-Arg
E)
none of these
70.
Which of the following fragments are formed when the following peptide is cleaved
using chymotrypsin?
Gly-Lys-Cys-Phe-Ile-Val-Tyr-Ala-Ser
A)
Gly-Lys-Cys, Phe-Ile-Val, Tyr-Ala-Ser
B)
Gly-Lys-Cys-Phe, Ile-Val-Tyr, Ala-Ser
C)
Gly-Lys-Cys-Phe, Ile-Val, Tyr-Ala-Ser
D)
Gly-Lys-Cys, Phe, Ile-Val-Tyr, Ala-Ser
E)
none of these
Ans:
B
71.
Which of the following fragments are formed when the following peptide is cleaved
using trypsin?
Gly-Lys-Cys-Phe-Ile-Val-Tyr-Ala-Ser
A)
Gly, Lys-Cys, Phe-Ile-Val, Tyr-Ala-Ser
B)
Gly-Lys, Cys-Phe-Ile-Val-Tyr-Ala-Ser
C)
Gly-Lys-Cys-Phe, Ile-Val-Tyr-Ala-Ser
D)
Gly-Lys, Cys, Phe-Ile-Val, Tyr-Ala-Ser
E)
none of these
Ans:
B
Ans:
A
72.
A peptide with 12 amino acid residues produced the following fragments when treated
with trypsin and chymotrypsin. Edman degradation of this peptide produced the
phenylthiohydantoin derivative of glycine. What is the structure of this peptide?
Trypsin: Gly-Leu-Phe-Arg, Cys-Tyr-Ile-Gly, Val-Trp-Ser-Lys
Chymotrypsin: Gly-Leu-Phe, Ser-Lys-Cys-Tyr, Ile-Gly, Arg-Val-Trp,
73.
Which of the following reagents is used to protect the amino group in the selective
synthesis of a dipeptide ala-val?
O O O
O O N
C
N
O
Cl
III III
O
O
Cl
IV
A)
I
B)
II
C)
III
D)
IV
E)
V
Ans:
B
74.
Which of the following dipeptides is formed when alanine and valine are reacted in the
presence of dicyclohexylcarbodiimide (DCC)?
A)
Ala-Val
B)
Val-Ala
C)
Ala-Ala
D)
Val-Val
E)
all of these
Ans:
E
Ans:
Gly-Leu-Phe-Arg-Val-Trp-Ser-Lys-Cys-Tyr-Ile-Gly
75.
Which of the following dipeptides is formed when leucine is treated with (Boc)2O and
glycine is treated with benzyl alcohol first and then reacted in the presence of DCC
followed by treatment with trifluoroacetic acid and aqueous NaOH?
A)
Gly-Leu
B)
Gly-Gly
C)
Leu-Gly
D)
Leu-Leu
E)
all of these
76.
Which of the following dipeptides is formed when tyrosine is treated with (Boc)2O and
proline is treated with benzyl alcohol first and then reacted in the presence of DCC
followed by treatment with trifluoroacetic acid and aqueous NaOH?
A)
Tyr-Pro
B)
Pro-Tyr
C)
Pro-Pro
D)
Tyr-Tyr
E)
all of these
Ans:
A
77.
Which of the following tripeptides is formed when alanine is treated with (Boc)2O and
proline is treated with benzyl alcohol first and then reacted in the presence of DCC
followed by treatment with aqueous NaOH. The dipeptide is then reacted with an ester
of leucine in the presence of DCC followed by treatment with trifluoroacetic acid and
aqueous NaOH?
A)
Ala-Pro-Leu
B)
Pro-Ala-Leu
C)
Leu-Ala-Pro
D)
Pro-Leu-Ala
E)
all of these
Ans:
A
Ans:
C
78.
Which of the following tripeptides is formed when serine is treated with (Boc)2O and
threonine is treated with benzyl alcohol first and then reacted in the presence of DCC
followed by treatment with aqueous NaOH. The dipeptide is then reacted with an ester
of isoleucine in the presence of DCC followed by treatment with trifluoroacetic acid and
aqueous NaOH?
A)
Ser-Tyr-Ile
B)
Ser-Thr-Ile
C)
Ile-Ser-Thr
D)
Ile-Ser-Tyr
E)
none of these
Ans:
B
79.
Provide a stepwise synthesis for the dipeptide Ser-Phe.
H2N CH C
CH2
OH
O
OH
H2N CH C
CH2
OH
O
Ser
80.
The method developed by ______is used to prepare larger peptides.
A)
Edman
B)
Strecker
C)
Merrifield
D)
none of these
81.
Which of the following is the correct sequence of the tetrapeptide that is formed by the
following reaction sequence?
Cl polymer
Boc
H
NO
O
OH
Boc
H
NOH
O
SH
DCC
CF3COH
O
HF
CF3COH
O
DCC
Boc
H
NOH
O
Ph CF3COH
O
DCC
Boc
H
NOH
O
CF3COH
O
A)
Cys-Ala-Phe-Ser
B)
Cys-Phe-Ala-Ser
C)
Ser-Ala-Phe-Cys
D)
Ser-Phe-Ala-Cys
E)
none of these
Ans:
D
Ans:
C
82.
Provide the steps necessary to prepare the tetrapeptide Thr-Val-Ile-Met using the
Merrifield synthesis.
83.
Which of the following is the correct sequence for the pentapeptide that is formed by the
following reaction sequence?
Cl polymer
Boc
H
NO
O
(CH2)2SCH3
DCC
CF3COH
O
HF
CF3COH
O
DCC
Boc-Gly CF3COH
O
DCC
Boc-Ala CF3COH
O
Boc-Lys
DCC
CF3COH
O
Boc-Leu
A)
Leu-Lys-Ala-Gly-Met
B)
Met-Gly-Ala-Lys-Leu
C)
Cys- Gly-Ala-Lys-Leu
D)
none of these
Ans:
A
84.
Which of the following is the correct sequence for the pentapeptide that is formed by the
following reaction sequence?
Cl polymer
Boc
H
NO
O
CH2OH
DCC
CF3COH
O
HF
CF3COH
O
DCC
Boc-Thr CF3COH
O
DCC
Boc-Pro CF3COH
O
Boc-Lys
DCC
CF3COH
O
Boc-Leu
A)
Ser-Thr-Pro-Lys-Leu
B)
Leu-Lys-Pro-Thr-Ser
C)
Thr-Thr- Pro-Lys-Leu
D)
none of these
85.
The ______ of amino acids in a protein is referred to as its primary structure.
A)
twisting
B)
sequencing
C)
folding
D)
none of these
Ans:
B
86.
The ______ structure of a protein is most important because the ______of the amino
acids determines its overall shape, function and properties.
A)
primary, twisting
B)
primary, sequencing
C)
secondary, twisting
D)
secondary, folding
E)
none of these
Ans:
B
Ans:
B
87.
The secondary structure of a protein is due to ________ between amino acid residues.
A)
hydrophobic interactions
B)
hydrogen bonding
C)
salt bridges
D)
disulfide linkage
E)
none of these
88.
The hydrogen bonding between the carbonyl group of an amino acid with the amino
group of the fourth amino acid farther along the chain leads to ______.
A)
parallel -pleated sheets
B)
antiparallel -pleated sheets
C)
-helix
D)
-helix
E)
none of these
Ans:
C
89.
Hydrogen bonding between the carbonyl group of an amino acid on one strand with the
amino group of the neighboring strand leads to ______.
A)
parallel -pleated sheets
B)
antiparallel -pleated sheets
C)
an -helix
D)
a -helix
E)
either A or B
Ans:
E
Ans:
B
90.
Which of the following is a secondary structure of fibroin found in spider web and silk?
A)
-pleated sheets
B)
-pleated sheets
C)
-helix
D)
-helix
E)
none of these
91.
Which of the following is a secondary structure of keratin found in hair?
A)
-pleated sheets
B)
-pleated sheets
C)
-helix
D)
-helix
E)
none of these
Ans:
C
92.
-keratin found in nails has more strength than -keratin found in hair due to presence
of more ___________.
A)
hydrophobic interactions
B)
salt bridges
C)
-helix
D)
disulfide bridges
E)
none of these
Ans:
D
Ans:
A
93.
Which of the following side chain interactions results in the tertiary structure of a
protein?
A)
hydrogen bonding
B)
salt bridges
C)
disulfide linkages
D)
hydrophobic interactions
E)
all of these
94.
Heating of proteins results in loss of activity and the process is referred to as _______.
A)
hydrolysis
B)
denaturation
C)
sequencing
D)
hydrophobic interactions
E)
all of these
Ans:
B
95.
Denaturation of proteins results in loss of ________structure.
A)
primary
B)
secondary
C)
tertiary
D)
B & C
E)
A, B & C
Ans:
D
Ans:
E
96.
The quaternary structure of a protein is due to:
A)
hydrogen bonding within the peptide
B)
aggregation of two or more polypeptides
C)
disulfide linkages within the peptide
D)
all of these
97.
Proteins that consist of linear polypeptide chains bundled together are classified
as________.
A)
globular proteins
B)
fibrous proteins
C)
lipoproteins
D)
all of these
Ans:
B
98.
-keratin found in hair, nails, and feathers is classified as ______.
A)
globular proteins
B)
fibrous proteins
C)
structural proteins
D)
B & C
E)
none of these
Ans:
D
99.
______proteins that catalyze biological reactions are called ______.
A)
fibrous, polypeptide
B)
globular, polypeptide
C)
fibrous, enzymes
D)
globular, enzymes
E)
none of these
Ans:
B
100.
Proteins that catalyze biochemical reactions are called ______.
A)
apoproteins
B)
peptides
C)
enzymes
D)
none of these
Ans:
C
101.
Hemoglobin found in blood is classified as a ______protein.
A)
structural
B)
regulatory
C)
transport
D)
fibrous
E)
none of these
Ans:
C
102.
Insulin involved in carbohydrate metabolism is classified as a ______protein.
A)
structural
B)
regulatory
C)
transport
D)
protection
E)
none of these
Ans:
B
103.
The heme group present in hemoglobin is called a _______.
A)
prosthetic group
B)
substrate
C)
cofactor
D)
none of these
Ans:
A