9. Amino Acids

Question 1

how many amino acids are in proteins

Answer 1

20 different

Question 2

describe the common structure of amino acids (2)

Answer 2

• they are chiral (a-carbon is asymmetric)
• all have same basic structure but differ in their R groups

Question 3

what are AA’s composed of (4)

Answer 3

1. central carbon
2. carboxylic acid group
3. amino group
4. R group

Question 4

is glycines a-carbon chiral?

Answer 4

NO
- its R group is a H so then there are two H’s attached to a-carbon

Question 5

a-amino acids occur as __ and __ enantionmers and it is determined but what

Answer 5

D (right) and L (left)
- determined by the position of the amino group attached to the a-carbon

Question 6

what enantiomer form is found naturally in proteins and what is it based on

Answer 6

L
- based on glyceraldehyde

Question 7

amino acids are ______ which means what

Answer 7

amphoteric
- dual acid/base nature

Question 8

at neutral pH amino acids exist as _____ and what are they

Answer 8

zwitterions
- can act as either acid/base with a net ZERO charge

Question 9

what is the isoelectric point

Answer 9

the pH when the molecule has a ZERO net charge