Chapter 3: Amino Acids Flashcards
1
Q
Glycine
Gly
G
A
2
Q
Alanine
Ala
A
A
3
Q
Proline
Pro
P
A
4
Q
Valine
Val
V
A
5
Q
Leucine
Leu
L
A
6
Q
Isoleucine
Ile
I
A
7
Q
Methionine
Met
M
A
8
Q
Phenylalanine
Phe
F
A
9
Q
Tyrosine
Tyr
Y
A
10
Q
Tryptophan
Trp
W
A
11
Q
Serine
Ser
S
A
12
Q
Threonine
Thr
T
A
13
Q
Cysteine
Cys
C
A
14
Q
Asparagine
Asn
N
A
15
Q
Glutamine
Gln
Q
A
16
Q
Lysine
Lys
K
A
17
Q
Arginine
Arg
R
A
18
Q
Histidine
His
H
A
19
Q
Aspartate
Asp
D
A
20
Q
Glutamate
Glu
E
A
21
Q
A
Glycine
Gly
G
22
Q
A
Alanine
Ala
A
23
Q
A
Proline
Pro
P
24
Q
A
Valine
Val
V
25
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Leucine
Leu
L
26
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Isoleucine
Ile
I
27
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Methionine
Met
M
28
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Phenylalanine
Phe
F
29
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Tyrosine
Tyr
Y
30
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Tryptophan
Trp
W
31
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Serine
Ser
S
32
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Threonine
Thr
T
33
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Cysteine
Cys
C
34
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Asparagine
Asn
N
35
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Glutamine
Gln
Q
36
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Lysine
Lys
K
37
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Arginine
Arg
R
38
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Histidine
His
H
39
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Aspartate
Asp
D
40
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Glutamate
Glu
E
41
The amino acid residues in protein molecules are almost exclusively which stereoisomer?
L-stereoisomers.
42
Which are nonpolar aliphatic and why?
Gly: R group is just a Hydrogen. No polarity, Hydrophobic.
Ala: R group is a CH3 which is nonpolar and hydrophobic
Proline: R group made up of C's and H's that connect back to the amino group. It is NP and hydrophobic.
Valine: R group C's and H's
Leucine
Isoleucine
Methionine: R group has an S but is nonpolar
43
Which are aromatic?
F, Y, W
44
Which are polar and uncharged?
S, T, C, N, Q
45
Which are positively charged?
K, R, H
46
Which are negatively charged?
D, E
47
What is a zwiterion?
German for "hybrid Ion", which can act as either an acid or a base. Amphoteric: can act as a base or acid. Ampholytes: amphoteric electrolytes
48
What are the normal pKa's of acetic acid and methylamine? How do the carboxyl and amino groups in an amino acid affect this?
4.8 and 10.6
Repulsion from the positively charged amino group and the departing proton lowers the pKa for the carboxyl group. The opposite charges for the NH3+ and COO- groups stablize the zwitterion, thereby lowering the pKa.
Alpha amino acid (glycine) = 2.34 and 9.60
49
What is an isoelectric point or Isoelectric pH?
pI: The characteristic pH at which the net electric charge is zero. This is useful in protein purification.
50
What is the difference between oligopeptides, polypeptides, and proteins?
Oligopeptides only have a few amino acid residues, polypeptides and proteins have many residues. Polypeptides generally have a molecular weight under 10,000. Proteins are higher.
