L4 - Fiberous and Globular proteins

Question 1

Describe the differences in structure between fibrous and globular proteins

Answer 1

Fibrous - usually have a Q-structure, and a lot od secondary structure
Globular - usually a complex tertiary structure

Question 2

What are common functions of globular proteins?

Answer 2

catalysts, transport, defence, regulation

Question 3

Describe a-keratin

Answer 3

• found in hair, nails, hooves, scales, beaks
• 2 chains coil around each other with hydrophobic and disulphide bonds
• about 300AAs repeating every 7, hydrophobic residues at A1 and A4

Question 4

Describe B-keratin

Answer 4

• lots of antiparallel B-sheets causing a ridged flat structure
• found in silk
• some non-sheet structures found causing slight flexibility

Question 5

Describe the formation of an a-keratin fibre from an a-helix

Answer 5

a-helix –> dimer –> proteofilament –> protofibril –> a-ker

Question 6

how many collagen fibres make up tropocollagen and what is needed for this reaction?

Answer 6

3 collagen fibres form a single tropocollagen fibre via a reaction where pro + lys are hydroxylated, requiring Vitamin C

Question 7

Describe gelatin formation

Answer 7

Gelatin is a derivative of collagen. It is created by the hydrolysis of links in collagen. The molecules disperse in water and form a gel on re-formation