Biochemistry

Question 1

When do amino acid zwitterions exist

Answer 1

Near an amino acids isoelectric point

Question 2

What is the isolelectric point of an amino acid

Answer 2

PH where the overall charge on the amino acid is zero

Question 3

More acidic than isoelectricc point means

Answer 3

NH2 group protonated but COOH unchanged so positive charge

Question 4

More basic than isoelectric point

Answer 4

COOH deprotonated but NH2 unchanged so negative charge

Question 5

How to identify amino acids

Answer 5

Chromatography and calculate Rf value

Question 6

Rf value =

Answer 6

Distance travelled by spot/distance travelled by solvent

Question 7

How to hydrolyse proteins

Answer 7

Add proteins to aqueous 6 moldm-3 hydrochloric acid and then heat under reflux for 24 hours

Question 8

When does disulphide bonding occur

Answer 8

Occurs between residues of the amino acid cysteine. The SH groups of the cysteines lose their hydrogens and form S-S bonds

Question 9

How does cisplatin kill cancer

Answer 9

Nitrogen on guanine bases form coordinate bonds with the platinum ion in cisplatin and replace the chlorine ligand
DNA helicase and DNA polymerase cannot act on the DNA strand and replicate it
Cell can’t replicate