Describe the fluid mosaic model of cell membrane.

The fluid mosaic model of the plasma membrane was given by Singer and Nicolson in 1972. According to this model, the plasma membrane is made of a phospholipid bilayer with cholesterol, protein, and carbohydrate molecules embedded in it. This membrane is 5-10nm in thickness. The phospholipid is formed of two layers of phospholipid molecules, with the polar head group of each phospholipid molecule (hydrophilic) facing the fluid side and the non- polar fatty acid chain of the phospholipid molecule (hydrophobic) facing the interior of the bilayer. So, the membrane surfaces that face the interior cytosolic side and the exterior side of the cell are hydrophilic. This membrane is semi-permeable in nature and allows only selective substances to pass through it.