Question

What are the components of the phospholipid bilayer, and how are they organized to form the plasma membrane?

Answer 1

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.