Amino acids

Question 1

what does amphoteric mean?

Answer 1

Having both acid and basic properties

amino acids are amphoteric

Question 2

Which amino acid DOESN’T rotate plane polarised light?

Answer 2

Glycine as it’s R group is just a hydrogen

so it doesn’t really have four different groups, so its not a chiral molecule

Question 3

What is a zwitterion?

Answer 3

It is an amino acid with both a positive and negative charge

dipolar ion

Question 4

What is the isoelectric point

Answer 4

The pH where the average overall charge on the amino acid is ZERO

Question 5

In more acidic conditions:

Answer 5

COO- gains a H+ and becomes COOH

the other side of the molecule is still NH3+

Question 6

what is ionised at the isoelectric point

Answer 6

Both groups : forming COO- and NH3+

This is a zwitterion

Question 7

In more alkaline conditions:

Answer 7

The NH3+ loses a hydrogen and becomes a NH2

the other side of the molecule is still COOH

Question 8

What are the 2 different ways to make the spots visible during TLC?

Answer 8

1) Ninhydrin solution

2) Fluorescent dye and UV light