The fluid mosaic model describes the typical plasma membrane as a phospolipid bilayer (1), composed of phosphates with fatty acid tails, which face each other inwardly. Within the phospholipid bilayer are different proteins, intrinsic proteins (2) which are associated with the bilayer from both sides, so is exposed to extra and intra cellular elements, these differ to extrinsic proteins (3) which are only associated with one layer of the phospholipid bilayer, so are only exposed to one of the sides of the cell membrane, not both. Within the bilayer is also cholesterol (4), which is between the fatty acid tails, which increases the stability of the membrane. Glycolipids (5) also occur within the model, carbohydrate chains attached to lipids, they have a role in cell signalling and cell attachment. Glycoproteins (6) are also a component of the model, carbohydrates attached to extrinsic proteins, which have similar roles to glycoproteins. Additional points: Channels Peripheral proteins, Transmembrane=intrinsic.