amino acids and proteins Flashcards Preview

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Flashcards in amino acids and proteins Deck (18)
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1
Q

structure of aa

A
H
amine group
carboxyl group
Rgroup 
chiral C
2
Q

what is an acid

A

proton donor

3
Q

base

A

proton acceptor

4
Q

isoelectric point

A

pH at which net charge is ), molecule would not migrate in an electric point

5
Q

peptide bond

A

rigid
planar
strong covalent bond
only broken down by proteases

6
Q

what can differ in in the R side chain

A
size 
shape
charge 
H bonding 
chemical reactivity
7
Q

classifications of amino acids/side chains

A

polar
non polar
acidic
basic

8
Q

polar aa

A

uneven charge distribution
forms H bonds, therefore hydrophilic
e.g. serine

9
Q

non polar aa

A
equal charge distribution
hydrophobic 
tend to be on the inside of protein 
some aromatic 
e.g. glycine
10
Q

acidic aa

A

have a - charge at neural pH
contain extra carboxyl group
e.g. aspartate

11
Q

basic aa

A

+ charge at neutral pH
contain amino group
e.g. lysine

12
Q

method used to separate proteins or aa

A
electrophoresis 
polyacrimide porous gel
protiens coated in - charge
move towards anode
separate by size 

2d electrophoresis
run in gradient of pH
move until isoelectric point is reached
i.e. measure size and isoelectric point

13
Q

post translational modification

A
lipid addition
oxidation/carboxylation/acetylation
cleavage
glycosylation (for tagging)
phosphorylation (alters intracellular signalling on/off)
14
Q

aa in disease

A

sickle cell anaemia - single point mutation in haemoglobin structure

15
Q

how can pH determine charge on aa

A

carboxyl and amine group ionisable
low pH - amine group protonated, carboyxl no charge
neutral pH- zwitter ion formed (no overall charge) ISOELECTRIC POINT
high pH - carboxyl group charged

16
Q

what occurs when side chain is not ionisable

A

amino acids are weak buffers

17
Q

effects of side chains on titration curves

A

gives 3rd pK due to side chain
At neutral pH
acidic gives negative change
Basic gives positive charge

18
Q

what is the change of aa dependant on

A

pH of environment