Constituents of cell membrane

Question

What are the fundamental constituents of cell membrane?

Answer 1

The cell membrane is made up of lipids, carbohydrates and proteins. The membrane lipids are phospholipids, a special kind of lipid to which one extremity a phosphate group is bound therefore assigning electrical charge to this area of the molecule. As phospholipids contain one electrically charged extremity and a long neutral organic chain they can systematize themselves in two layers of related molecules: the hydrophilic part (or polar) of each layer faces outwards in contact with water (that is, a polar molecule too) of the extracellular and intracellular space and the hydrophobic chains (that is, non-polar) face inwards isolated from the water. Since this kind of membrane is made up of two phospolipid layers it is also termed as a bilipid membrane.

Membrane proteins are embedded and scattered in the compact bilipid structure. Carbohydrates emerge in the outer surface of the membrane related to certain of such proteins under the form of glycol-proteins or bound to phospholipids making glycolipids. The membrane carbohydrates make the glycocalix of the membrane.

This explanation (with additional explanations) is termed as the fluid mosaic model regarding the structure of the cell membrane.