The fluid mosaic model 1972

• Membrane is made from phospholipid molecules, proteins, cholesterol, glycoproteins and glycolipids
• The inside and outside of the cell is aqueous, phospholipid molecules form a continuous bilayer with their hydrophilic phosphate/glycerol heads in water and their hydrophobic fatty acid hydrocarbon chain away from water
• The polar head is Water soluble and the non polar tails are insoluble in water and repel it
• Proteins can be intrinsic ( pass through ) or extrinsic ( in one half of bilayer or attached to the surface ) they can be fibrous or globular and can be receptors, channels or carriers
• Membrane proteins are called glycoproteins if they have carbohydrate groups attached
• Proteins are dotted around in a mosaic pattern
• The bilayer is fluid/liquid , not rigid as the hydrocarbon chains “wiggle” and constantly move sideways in a random motion, hence the fluid mosaic model
• Cholesterol ( a lipid ) fits between the phospholipids in the membrane and acts as a modulator for fluidity
• Cells are adapted for rapid transport across their internal or external membranes by an increase in surface area due to folding