Amino acids (lectures 2&3) Flashcards
(61 cards)
1
Q
Ala
A
alanine
2
Q
Arg
A
arginine
3
Q
Asn
A
asparagine
4
Q
Asp
A
aspartic acid
5
Q
Cys
A
cysteine
6
Q
Glu
A
glutamic acid
7
Q
Gln
A
glutamine
8
Q
Gly
A
glycine
9
Q
His
A
histadine
10
Q
Ile
A
isoleucine
11
Q
Leu
A
leucine
12
Q
Lys
A
lysine
13
Q
Met
A
methionine
14
Q
Phe
A
phenylalanine
15
Q
Pro
A
proline
16
Q
Ser
A
serine
17
Q
Thr
A
threonine
18
Q
Try
A
tryptophan
19
Q
Tyr
A
tyrosine
20
Q
Val
A
valine
21
Q
A
A
alanine
22
Q
R
A
arginine
23
Q
N
A
asparagine
24
Q
D
A
aspartic acid
25
C
cysteine
26
E
glutamic acid
27
Q
glutamine
28
G
glycine
29
H
histidine
30
I
isoleucine
31
L
leucine
32
K
lysine
33
M
methionine
34
F
phenylalanine
35
P
proline
36
S
serine
37
T
threonine
38
W
tryptophan
39
Y
tyrosine
40
V
valine
41
aromatic R groups
phenylalanine
tyrosine
tryptophan
42
positively charged R groups
lysine
arginine
histidine
43
negatively charged R groups
aspartate
| glutamate
44
non polar, aliphatic R groups
```
glycine
alanine
valine
leucine
methionine
isoleucine
```
45
polar, uncharged R groups
```
serine
threonine
cysteine
proline
asparagine
glutamine
```
46
what are the side chains of negatively charged amino acids called?
carboxylates
| COO- + H+
47
what are the side chains of positively charged amino acids called?
primary amino groups
| NH3+
48
whats special about glycine?
has 2 hydrogens attached to an alpha carbon
has no D & L form
is found in flexible regions of the protein since its small side chain
it is a neurotransmitter
49
whats special about cysteine?
has a thiol group (SH)
like hydroxyl but H is lost more easily
can bond to other cysteine by a disulphide bond
binds to metals in proteins
50
when do proteins use disulphide bonds?
to increase their stability when working outside the cell
51
whats special about histadine?
acts as a base - accepts a H+ below neutral pH
not strongly charged in the human body
can bind metals
52
whats special about aromatic amino acids?
```
are the largest
hydrophobic
found in the core of the protein
absorb light & used in spectroscopy
essential in the human diet
```
53
what is phenylketonuria?
the inability to breakdown excess phenylalanine
54
structure of amino acids
have complementary ends that fit together
each amino acid has a C & an N terminus
order determines protein character
is a zwitterion - no net charge
form stereoisomers & optical isomers
only L form found in proteins
55
how are amino acids joined?
peptide bonds
condensation reaction
a covalent bond
peptide bond is rigid as it has a partial double bond character
56
primary structure
linear sequence of amino acids joined by peptide bonds
57
what is chloramphenicol?
an antibiotic used to treat eye infections & penicillin resistant meningitis
part of it looks like a peptide bond
binds to the bacterial ribosome where peptide bonds are made & kills the bacteria
58
secondary structure
stabilised by H bonds
alpha helix
beta pleated sheet
59
the alpha helix
not made by DNA
H bonds are made from the carbonyl oxygen on residue N to the amide nitrogen on residue N+4
has 3.6 residues per turn
successive side chains point outwards 100 degrees apart
60
the beta sheet
```
not made by DNA
hydrogen bonds are between strands
all side chains point alternatively up & down
2 residue repeat
forms sheets
```
61
whats the different between antiparallel & parallel beta sheets?
antiparallel have straight H bonds so are a lot stronger
| parallel are weaker as H bonds have a kink so less stable
