amino acids

Question 1

Cysteine: a ??? bond can be reversibly formed by oxidation of 2 molecules of cysteine = very Hydrophobic (non-polar) residues.

Answer 1

a disulfide bond

Question 2

Cysteine: disulfide bonds between cys residues stabilise the ??? of many ???

Answer 2

structures of many proteins

Question 3

amino acids can act as both a ??? donator and proton ???

Answer 3

proton donator and proton acceptor

Question 4

amphoteric means

Answer 4

amino acids can act as both acid and base

Question 5

at an acidic pH the COOH group (carboxyl group) is ??? and amino acid is CATIONIC (positive)

Answer 5

protonated

Question 6

At neutral pH, carboxyl group is ??? but amino group is protonated

Answer 6

deprotonated

Question 7

TRUE or FALSE
Zwitteron = 1/2 protonated and 1/2 deprotonated

Answer 7

TRUE

Question 8

at alkaline pH, amino group is ??? and amino acid is ANIONIC (negative)

Answer 8

neutral
i.e NH3 becomes NH2

Question 9

pl refers to the isoelectric point, meaning the pH at which amino acid net charge is

Answer 9

0