Aa, proteins + DNA Flashcards
1
Q
Why is aa amphoteric?
A
Has COOH + NH2
2
Q
Define zwitterion
A
Has both +ve + -ve charge, exists near aa isoelectropoint (pH where overall charge is 0)
3
Q
Outline how to carry out thin layer chromatography to identify unknown aa
A
- Draw pencil line near bottom of TLC + put conc spot of mixture of aa
- Dip into solvent
- As solvent spreads, diff. aa move at diff rates
- When solvent nearly reaches top, remove + mark solvent front
- Make aa spot visible by: spraying ninhydrin sol, turns purple/plate that has fluorescent dye + put under UV
- Work out rf value = distance travelled by spot/distance travelled by solvent
4
Q
What are the conditions to hydrolyse a protein?
A
- Hot aqueous HCL
- Heat
- Reflux
5
Q
Outline the structure of proteins
A
- 1º - seq. aa
- 2º - peptide links form H bonds forming alpha helix + beated pleated sheets
- 3º - Folded + coiled further by forming extra bonds to make 3D shape
6
Q
What are the 2 bonds that hold a proteins shape?
A
- H bonds - btw polar groups
- Disulfied bonds - cystein contains thiol group, diff cystein lose H + join
7
Q
Why do enzymes have high specificity?
A
- Made of aa containing chiral centres
- Makes active site stereospecific - only work on 1 enantiomer
8
Q
What makes the sugar phosphate backbone?
A
Covelant bonds btw phosphate group (OH) + sugar (H) of another
9
Q
How do H bond form?
A
Btw polar +ve H + lone pair on O or N
10
Q
How does cisplatin prevent cancer?
A
- N on G forms co-ordinate bond w/ cisplatin Pt ion, replacing Cl-
- 2nd N on another guanine bonds to Pt + replaces 2nd Cl-
- Causes strands to kink, means DNA can’t unwind + so can’t replicate
11
Q
What are the side effects of cisplatin + how do you improve it?
A
- Cisplatin can bind to normal cells, bad for cells that replicate frequently (hair + blood) - causes hairloss + suppress immune system
- Give low dosage + target tumour
