What are the components of the phospholipid bilayer, and how are they organized to form the plasma membrane?
1 Answer
The most abundant membrane lipids are the phospholipids. These have a polar ( hydrophilic)head group and two hydrophobic hydrocarbon tails. The tails are usually fatty acids of varying lengths.
Explanation:
Hydrophilic molecules can form either favourable electrostatic interactions or H bonds with water molecules.
Hydrophobic molecules are insoluble in water . When dispersed in water , they force the adjacent water molecules to reorganise into ice like cages, that surround the hydrophobic molecules.
For the above reason , lipid molecules spontaneously aggregate to bury their hydrophobic tails in the interior and expose their hydrophilic heads to water.
Being cylindrical , phospholipid molecules spontaneously form bilayer in aqueous environments. In this energetically most favourable arrangement , the hydrophilic heads, face the water at each surface of the bilayer and the hydrophobic tails are shielded from the water in the interior.
A lipid bilayer thus has self sealing properties, that make it an ideal structure for cell membranes.
