Fluid mosaic model of plasma membrane

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