Proteins

Question 1

Roles of protein

Answer 1

1. Enzymes
2. Transport (hemoglobin)
3. Signalling (hormones)
4. Contractile (musculoskeletal)
5. Defense (immunity)
6. Structural (hair, keratin, etc.)

Question 2

General structure

Answer 2

1. Amino group
2. Side chain (differs in various amino acids)
3. Carboxyl group

Question 3

Classification of the 20 amino acids

Answer 3

1. Non-polar sidechains (+ and - charges balance each other, generally cannot dissolve in water)
2. Polar, uncharged sidechains (unbalanced distribution of + and - charges allows water to “stick” and dissolve polar substances)
3. Acidic sidechains (Acidic substances lose an “acidic” proton to lower the pH of the solvent)
4. Basic sidechains (Basic substances gain a proton to raise the pH of the solvent)

Question 4

Classification of proteins

Answer 4

1. Simple proteins (contains only amino acid residues)

2. Conjugated proteins (contains other biomolecules)

Question 5

Structures of proteins

Answer 5

1. Primary
   - actual sequence of amino acids in a protein
2. Secondary
   - the type of regular repeating structure
3. Tertiary
   - Interaction of side chains
4. Quatemary
   - Association of 2 or more polypeptide chains to form a multisubunit molecule