THE STRUCTURE OF THE PLASMA MEMBRANE
1. The Fluid-Mosaic Model of the plasma membrane was proposed by S. Singer and G. Nicolson in 1972. They proposed that membrane proteins are dispersed throughout and inserted into the phospholipid bilayer.
2. Pictured as "mosaic" because it has various protein molecules embedded in the phospholipid bilayer. The membrane is "fluid" cause the proteins and phospholipid molecules drift laterally in the membrane.
3. Two parts in each phospholipid molecule:
(i) a polar head which is hydrophilic ('keen of water')
(ii) a pair of non-polar fatty acid tails which are hydrophobic ('hate of water').
4. Phospholipids are arranged in bilayer = phospholipid bilayer.
5. Types of proteins embedded :
(i) pore proteins : has a pore to provide a passage for solutes to pass through the plasma membrane.
(ii) carrier proteins :acts as a carrier to carry molecules across the plasma membrane.
The Fluid-Mosaic Model of the plasma membrane
The movement of a lipid-soluble molecule through the phospholipid bilayer
A simulation of the plasma membrane structure