Explain the association of Carbohydrate to the plasma membrane and its significance.

Explanation

Plasma membrane is made up of lipids and proteins. Later, biochemicals investigations clearly revealed that the cell membranes also possess protein and carbohydrate. They are presents short, unfranched or branched chains of sugars (oligosaccharides) attached either to exterior ectoproteins or the polar ends of phospholipids at the external surface of the plasma membrane. All types of oligosaccharides of the plasma membrane are formed by various combinations of six principle sugars like D-galactose, D-mannose, L-fructose, N-acetyl neuramic acid (sialic acid), N-acetyl D-glucosamine and N-acetyl - D - galactosamine.
Significance :
(i) Glycophorins are found to contain certain antigenic determinants for the ABO Blood groups and MN flood groups.
(ii) Sialic acid contents a high negative change to the cell surface of erythrocyte.