L11 Protein Structure

Question 1

What are proteins made of?

Answer 1

Proteins are polymers of amino acids linked by peptide bonds.

Question 2

What is a peptide bond?

Answer 2

A bond formed by condensation between the α-amino group and carboxyl group of two amino acids.

Question 3

Name the four levels of protein structure.

Answer 3

Primary (sequence), Secondary (α-helix/β-sheet), Tertiary (3D shape), Quaternary (multi-chain arrangement).

Question 4

What interactions stabilise protein folding?

Answer 4

H bonds, ionic bonds, hydrophobic interactions, Van der Waals forces, disulfide bonds.

Question 5

What is the difference between α-helix and β-sheet?

Answer 5

α-helix: Coiled, H bonds between n & n+4.

β-sheet: Flat/twisted, strands are parallel or anti-parallel.

Question 6

What is protein denaturation?

Answer 6

Loss of 3D structure and function due to heat, pH, detergents.

Question 7

What is a protein domain?

Answer 7

An independently folding unit often linked to specific functions.

Question 8

How do proteins recognise other molecules?

Answer 8

Via multiple weak interactions: H bonds, ionic bonds, hydrophobic interactions.

Question 9

Give an example of a structural protein.

Answer 9

Collagen (connective tissue) or Keratin (hair, skin).

Question 10

Give an example of a transport protein.

Answer 10

Haemoglobin (O₂ transport) or Porin (membrane channel).

Question 11

What is de novo protein design used for?

Answer 11

Vaccines, enzyme therapies, drug development, sustainability.