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Chapter Twenty Five
1.
In -amino acids the amino and carboxylic acid groups are separated by ____,
A)
two carbon atoms
B)
one carbon atom
C)
peptide linkage
D)
amide linkage
E)
none of these
2.
Amino acids are connected to each other by____________.
A)
an ether linkage
B)
a peptide linkage
C)
an ester linkage
D)
none of these
3.
When four amino acids are connected to each other, they form ____________.
A)
a tripeptide
B)
a protein
C)
a polypeptide
D)
a tetrapeptide
E)
none of these
4.
When thirty amino acids are connected to each other, they form ____________.
A)
a tripeptide
B)
a protein
C)
a polypeptide
D)
a tetrapeptide
E)
none of these
5.
When more than fifty amino acids are connected to each other, they form _________.
A)
a tripeptide
B)
a protein
C)
a polypeptide
D)
a tetrapeptide
E)
none of these
6.
Proteins found in humans have all amino acids with ____configuration.
A)
D
B)
L
C)
meso
D)
A & B
E)
none of these
7.
Which of the following amino acids is achiral?
A)
alanine
B)
leucine
C)
glycine
D)
phenylalanine
E)
none of these
8.
Which of the following is a correct structure for L-valine?
H2N H
CH(CH3)2
OOH
H NH2
CH(CH3)2
OOH
H2N H
CH2CH(CH3)2
OOH
H NH2
CH2CH(CH3)2
OOH
H NH2
CH3
OOH
III III IV V
A)
I
B)
II
C)
III
D)
IV
E)
V
9.
Which of the following is a correct structure for D-leucine?
H2N H
CH(CH3)2
OOH
H NH2
CH(CH3)2
OOH
H2N H
CH2CH(CH3)2
OOH
H NH2
CH2CH(CH3)2
OOH
H NH2
CH3
OOH
III III IV V
A)
I
B)
II
C)
III
D)
IV
E)
V
10.
Which of the following amino acids have a basic side chain?
III III IV V
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
HN
H2N CH C
CH2
OH
O
C
NH2
OHN
C OH
O
A)
I & II
B)
I, II & IV
C)
III & V
D)
I, II, III & IV
E)
all of these
11.
Which of the following amino acids have an acidic side chain?
III III IV
V
H2N CH C
CH2
OH
O
CH2
C
OH
O
H2N CH C
CH2
OH
O
C
OH
O
H2N CH C
CH2
OH
O
SH
H2N CH C
CH2
OH
O
OH
H2N CH C
CH2
OH
O
OH
A)
I & III
B)
I, II & III
C)
IV & V
D)
II, IV & V
E)
all of these
12.
Which one of the following amino acid does not have an L-isomer?
A)
valine
B)
alanine
C)
leucine
D)
glycine
E)
none of these
13.
Which of the following naturally occurring amino acids do not have S configuration?
A)
alanine
B)
cysteine
C)
tyrosine
D)
isoleucine
E)
none of these
14.
Which of the following is a predominant form of lysine at pH 14?
OH
O
NH3
H3N
O
O
NH3
H3N
OH
O
NH2
H2N
O
O
NH2
H2N
O
O
NH2
H3N
III III
IV V
A)
I
B)
II
C)
III
D)
IV
E)
V
15.
Which of the following is a predominant form of aspartic acid at pH 1?
OH
O
NH2
O
OH
OH
O
NH3
O
OH
O
O
NH2
O
O
OH
O
NH3
O
O
O
O
NH3
O
OH
I II III
IV V
A)
I
B)
II
C)
III
D)
IV
E)
V
16.
Which of the following is a predominant form of serine at physiological pH?
HO OH
O
NH2
HO OH
O
NH3
HO O
O
NH3
O OH
O
NH3
O O
O
NH3
III III IV V
A)
I
B)
II
C)
III
D)
IV
E)
V
17.
Which of the following is a predominant form of asparagine at physiological pH?
OH
O
NH2
O
NH2
OH
O
NH3
O
NH2
O
O
NH2
O
NH2
O
O
NH3
O
NH3
O
O
NH3
O
NH2
III III
IV V
A)
I
B)
II
C)
III
D)
IV
E)
V
18.
Which of the following is a predominant form of arginine at pH 2?
OH
O
NH3
N
H
H3N
NH
I
OH
O
NH3
N
H
H2N
NH2
II
OH
O
NH3
N
H
H3N
NH2
III
OH
O
NH3
N
H2
H3N
NH2
IV
OH
O
NH3
N
H2
H3N
NH
V
A)
I
B)
II
C)
III
D)
IV
E)
V
19.
Provide the structure of a predominant form of alanine at pH 2?
20.
Provide the structure of a predominant form of valine at pH 10?
21.
Which of the following is true about the amino acids with isoelectric point around
pH 10?
A)
the side chain must be acidic
B)
the side chain must be basic
C)
the side chain must be polar
D)
the side chain must be non polar
E)
none of these
22.
Which of the following is true about the amino acids with isoelectric point around
pH 3?
A)
the side chain must be acidic
B)
the side chain must be basic
C)
the side chain must be polar
D)
the side chain must be non polar
E)
none of these
23.
The pH at which the concentration of the zwitterionic form of an amino acid is at a
maximum value is called the _______.
A)
dipolar point
B)
electric point
C)
neutral point
D)
isoelectric point
E)
none of these
24.
What is the pI of the following amino acid?
OH
O
NH2
O
OH
pKa1=1.88 pKa2=9.60 pKa3=3.65
A)
2.76
B)
5.74
C)
6.62
D)
7.5
E)
none of these
25.
What is the pI of the following amino acid?
OH
O
NH2
pKa1=2.18 pKa2=8.95 pKa3=10.53
H2N
A)
5.56
B)
6.35
C)
9.74
D)
10.53
E)
none of these
26.
What is the pI of the following amino acid?
OH
O
NH2
pKa1=2.32 pKa2=9.62
A)
1.16
B)
4.81
C)
5.97
D)
9.62
E)
none of these
27.
Which of the following amino acids have a pI around pH 10?
H2N CH C
CH2
OH
O
C
NH2
O
H2N CH C
CH2
OH
O
C
OH
O
H2N CH C
CH2
OH
O
CH2
CH2
CH2
NH2
H2N CH C
CH2
OH
O
OH
H2N CH C
CH
OH
O
OH
CH3
III III IV
V
A)
I
B)
II
C)
III
D)
IV
E)
V
28.
Which of the following amino acids have a pI around pH 3?
H2N CH C
CH2
OH
O
C
NH2
O
H2N CH C
CH2
OH
O
C
OH
O
H2N CH C
CH2
OH
O
CH2
CH2
CH2
NH2
H2N CH C
CH2
OH
O
OH
H2N CH C
CH
OH
O
OH
CH3
III III IV
V
A)
I
B)
II
C)
III
D)
IV
E)
V
29.
Which of the following is used to detect the presence of amino acids using
chromatography?
A)
2,4-DNP
B)
methyl orange
C)
phenolphthalein
D)
ninhydrin
E)
none of these
30.
Which of the following amino acids will migrate towards the cathode at pH 7?
Glycine: pI=6.0
Lysine: pI=9.7
31.
Which of the following amino acids will migrate towards the anode at pH 7?
Glycine: pI=6.0
Lysine: pI=9.7
32.
Which of the following amino acids will migrate towards the anode at pH 6?
Phenylalanine: pI = 5.5
Leucine: pI = 6
33.
Which of the following amino acids will not migrate towards the cathode/anode at pH
6?
Phenylalanine: pI = 5.5
Leucine: pI = 6
34.
Which of the following amino acids will move the farthest when subjected to
electrophoresis at pH 7?
I II III
aspartic acid alanine histidine
pI=6.01
pI=2.76 pI=7.58
A)
I
B)
II
C)
III
D)
II & III
E)
none of these
35.
Which amino acid is produced from the following reaction sequence?
OH
O
1. Br2/PBr3
2. H2O
excess NH3
A)
alanine
B)
valine
C)
leucine
D)
isoleucine
E)
none of these
36.
Which amino acid is produced from the following reaction sequence?
OH
O
1. Br2/PBr3
2. H2O
excess NH3
A)
alanine
B)
valine
C)
leucine
D)
isoleucine
E)
none of these
37.
Which amino acid is produced from the following reaction sequence?
1. Br2/PBr3
2. H2O
excess NH3
4-methylpentanoic acid
A)
alanine
B)
valine
C)
leucine
D)
isoleucine
E)
none of these
38.
Which amino acid is produced from the following reaction sequence?
1. Br2/PBr3
2. H2O
excess NH3
3-methylpentanoic acid
A)
alanine
B)
valine
C)
leucine
D)
isoleucine
E)
none of these
39.
How will you prepare phenylalanine using a Hell-Volhard-Zelinski reaction?
40.
How will you prepare glycine staring with ethanol and using a Hell-Volhard-Zelinski
reaction?
41.
Which amino acid is produced from the following reaction sequence?
EtO OEt
OO
HN
O
Br
H3O+
1. NaOEt
2. heat
A)
alanine
B)
valine
C)
leucine
D)
isoleucine
E)
none of these
42.
Which amino acid is produced from the following reaction sequence?
EtO OEt
OO
HN
O
H3O+
1. NaOEt
2. 1-chloro-2-methylpropane heat
A)
alanine
B)
valine
C)
leucine
D)
isoleucine
E)
none of these
43.
Provide the structure of the amino acid produced from the following reaction sequence.
EtO OEt
OO
HN
O
H3O+
1. NaOEt
2. heat
Br
HO
44.
Provide the structure of the amino acid produced from the following reaction sequence.
EtO OEt
OO
HN
O
H3O+
1. NaOEt
heat
SBr
2.
45.
Which of the following aldehydes would produce isoleucine using a Strecker synthesis?
A)
3-methylbutanal
B)
2-methylbutanal
C)
2-methylpropanal
D)
propanal
E)
none of these
46.
Which of the following aldehydes would produce glycine using a Strecker synthesis?
A)
methanal
B)
ethanal
C)
propanal
D)
none of these
47.
Which amino acid is produced from the following reaction?
H
1. NH4Cl, NaCN
2. H3O+
HS
O
A)
methionine
B)
serine
C)
cysteine
D)
lysine
E)
none of these
48.
Which amino acid is produced from the following reaction?
H
1. NH4Cl, NaCN
2. H3O+
HO
O
A)
methionine
B)
serine
C)
cysteine
D)
lysine
E)
none of these
49.
Provide the reagents necessary to prepare phenylalanine using a Strecker synthesis.
50.
Provide the structure of the amino acid produced from the following reaction.
1. NH4Cl, NaCN
2. H3O+
O
H
51.
Which of the following alkenes is used to prepare isoleucine using an asymmetric
catalytic hydrogenation?
H2/(R)-(-)Ru(BINAP)Cl21. NaOH/H2O
2. H3O+L-isoleucine
OH
O
NHAc
OH
O
NHAc
OH
O
NHAc
III III
OH
O
NHAc
IV
A)
I
B)
II
C)
III
D)
IV
E)
none of these
52.
Provide the structure of the amino acid produced from the following reaction sequence.
H2/(R)-(-)Ru(BINAP)Cl21. NaOH/H2O
2. H3O+
OH
O
NHAc
53.
Which of the following is a correct bond-line structure for a tripeptide Val-Asp-Ala?
H2N
H
N
N
H
OH
O
O
OOH
O
H2N
H
N
N
H
OH
O
O
OOH
O
H2N
H
N
N
H
OH
O
O
OOH
O
H2N
H
N
N
H
OH
O
O
ONH2
O
III
III IV
A)
I
B)
II
C)
III
D)
IV
E)
none of these
