CB2 Biological Membranes

Question 1

List the general functions of biological membranes

Answer 1

• Self-organising & self-healing
• serve to partition aqueous compartments

Question 2

Describe the structural features of the lipid components

Answer 2

Cholesterol: rigid ring structure & flexible tail - restricts fluidity near surface, promotes fluidity at the centre
Phosphoglycerides: choline/ethanolamine/serine, phosphate, glycerol, X2 fatty acids
Sphingomyelin: choline, phosphate, sphingosine, fatty acid
Glycolipids: galactose, sphingosine, fatty acid

Question 3

Explain the structure & fluidity of the lipid bilayer

Answer 3

• Unsaturated fatty acids (double bonds) increases fluidity
• saturated fatty acids create a more gel-like consistency
• proteins move across the plane of the membrane constantly

Question 4

Describe the types of membrane protein & explain the techniques used to identify them

Answer 4

• Transporters
• anchors
• receptors
• enzymes

Freeze-fracture
A method used to study membrane proteins
- freeze cells
- the fracture then separates 2 leaflets of membrane along a dividing line