amino acids, proteins and DNA

Question 1

why do nearly all amino acids exist as a single negative enantiomer

Answer 1

so that they ‘fit’ into the correct cells within living organisms

Question 2

how do amino acids react in acidic conditions

Answer 2

lone electron pair more likely to accept hydrogen atom production a positive end to the molecule

H3N+

Question 3

how do amino acids react in basic conditions (low pH)

Answer 3

the hydrogen atom on the -OH is more likely to be lost producing a negative end to the molecule

COO-

Question 4

when is a zwitterion formed

Answer 4

at isoelectric point
when overall pH of molecule is 0

Question 5

what is a zwitterion

Answer 5

when the H2N gains a proton and the COOH loses its proton

Question 6

what are disulphide bridges

Answer 6

sulfur - sulfur bonds that hold together tertiary structures

they keep protein structure stable by losing 2 hydrogen atoms

Question 7

what does stereospecific and how does it apply to enzymes

Answer 7

means they can only break down a single enantiomer and will have no effect on the other optical isomer

Question 8

how does cisplatin work as an anti cancer drug

Answer 8

bonds to strands of mutated DNA to prevent it from replicating via ligand replacement with guanine s

Question 9

how does cisplatin cause side effects and what are they

Answer 9

bonds to headed DNA strands
hair loss