The plasma membrane surrounds the cell. Chemically plasma membrane is composed of: (a) Protein: 60 to 80% (b) Phospholipids: 20 to 40% (e) Cholesterol in small amount (d) Carbohydiutes in small amount Different models were put forward about the physiochemical nature of plasma membrane.
Lipids are nonpolar organic molecules that are insoluble in polar water but soluble in nonpolar organic solvents like ether, alcohol, and chloroform. Lipids show hydrophobic behavior. The behaviour is associated with the chemical structures of lipids. Lipids have high proportion of C-1-I bonds. C-1-I