L3 - Proteins and Amino Acids

Question 1

State the chemical structure of a a) carboxylic acid group b) amine group

Answer 1

a) -COOH

b) -NH2

Question 2

Name 2 important amino acids that are a) non-polar b)polar uncharged

Answer 2

a) alanine: CH3,
phenylalanine: CH3-benzene

b) serine: CH2OH
tyrosine: CH2-benzene-OH

Question 3

Name 2 amino acids that are a) polar b) special/different

Answer 3

a) aspartic acid: -CH2-COO-
Lysine: -(CH2)4-NH3+

b) cysteine: CH2-SH
glycine: H

Question 4

What kind of reaction occurs when 2 amino acids mob?

Answer 4

An condensation reaction creates a peptide bond between the 2 amino acids

Question 5

Briefly describe primary and secondary structure

Answer 5

Primary structure: the sequence of amino acids

Secondary structure: due to dipoles on AA chains, hydrogen bonds form and create either a B-pleated sheet or a-helix

Question 6

How many amino acids are there per turn in a na-helix?

Answer 6

3.6

Question 7

In what direction do side chains face in an a-helix?

Answer 7

outwards

Question 8

Desribe between what groups hydrogen bonds usually form between a-helixs

Answer 8

Between C=O and NH

Question 9

What shape do hydrogen bonds form in a B-sheet?

Answer 9

A zig-zag as side chains alternate between up and down