proteins 3.1.4 (module 1)

Question 1

amino acid structure

Answer 1

(R group) R
I (carboxyl)
NH —– C —- COOH
(amine) I
H

Question 2

what is the bond between amino acids?

Answer 2

peptide bonds

Question 3

what is the structure of a protein?

Answer 3

• primary structure (sequence and number of amino acids in polypeptide chain)
• secondary structure (folding of polypeptide chain by forming hydrogen bonds between amine and carboxyl groups eg beta pleated sheet and alpha helix)
• tertiary structure (unique 3B globular structure (further folding) forming hydrogen ionic disulphide bonds between R groups etc)
• quaternary structure (more than one polypeptide chain)

Question 4

what is the test for proteins?

Answer 4

• add equal volumes of buret reagent to sample
• shake gently
• positive lilac purple colour

Question 5

what is a globular protein?

Answer 5

• compacted round molecule
• soluble
• metabolic functions (eg haemoglobin myoglobin enzymes)

Question 6

what is a fibrous protein?

Answer 6

• long coiled flat sheets
• insoluble
• structural functions (keratin collagen)
• high tensile strength