3

Question 1

Biomembranes

Answer 1

Supra-molecular self-organizing structures that consist mainly of lipids and proteins which is hold by weak non-covalent interactions.

Question 2

Types of Lipids (15 - 80 %):
Phospholipids
Sterol lipids
Glycolipids
Minor lipids:

Answer 2

main compound of the lipid bilayer (20 - 50 % of the total lipid content)

cholesterol, improves the barrier function of the membrane inhibiting fast phase transitions in the bilayer during temperature changes (0 - 20 %)

receptors (5-30 %)

Vitamin А and Е, fatty acids etc. (< 1 -2%)

Question 3

Types of membrane proteins:
Integral proteins
Lipid anchored proteins
Peripheral proteins

Answer 3

Ion channels, proton pumps, trans-membrane receptors
Some G-proteins (signal transduction)
Some enzymes and hormones

Question 4

Biomembrane functions:

Answer 4

Barrier = low permeability for ions
Transport = protein channels, carriers or pumps for active transport of ions or molecules
Mechanical = maintains the integrity and shape of cells,
Signaling = specific binding sites (receptors) for signaling molecules
atalytic = forms a dynamic matrix for enzymes 
Protecting = protects the cell from different harmful or destructing factors of biological, chemical or physical nature.

Question 5

Physical properties:

Answer 5

Mechanical– fluidity ⇒ stability and deformability
Electrical-all cellular membranes have a high resistance
Optical -refraction and absorption of light,