Fluid mosaic model of plasma membrane

• Important feature: mobility of components within the bilayer.
• Mobility includes lateral and rotational mobility.
• Phospholipid molecules flips flops once in several hours.
• On the basis of this model,” membranes are two-dimensional solution of oriented lipids and globular protein”.
• Lipid bilayer acts as permeability barrier.
• Spontaneous rotation of lipid from one face of membrane to other is slow process known as flip flop.
• A phospholipid molecule takes about 109 times long to flip-flop across a membrane.
• Protein and lipid are free to move laterally in the place of bilayer.
• In Animal, cholesterol is the key regulator of the membrane fluidity.