Classification of polysaccharide

A. Homopolysaccharide:

• Contain single type of monomeric units.
• Some serve as starch in plant and glycogen in Animal.

I. Starch:

• Abundant in tubers of potatoes and seeds.
• Starch contains two types of glucose polymer. i.e., Amylase ( long unbranched chain of D-glucose units) and Amylopectin (Highly branched).

II. Cellulose:

• Fibrous, tough, water insoluble substance in the cell wall of plants particularly in trunk, stem, etc.
• Everything is same between D-glucose and Arabinose except -CH₂OH group is replaced by -H bond.
• This bacterial metabolism is often associated with the production of uncomfortable volume of gas, chiefly CH₄ and H₂.

III. Glycogen:

• Main Storage polysaccharide of animal cells.
• Glycogen is specially abundant in liver and constitute about 7% of the wet weight.
• Average chain length is only 8 glucose units.
• Molecular mass is very high and gives red color with iodine.
• Open circle represents glucose units.
• Chin length is 8 glucose units in Average.

IV. Chitin:

• Linear homopolysaccharide composed of N-acetyl-D-Glucosamine residues in β-linkage.
• The only difference from cellulose is the replacement of hydroxyl group of C-2 with an acetylated group.
• Indigestible by vertebrate animals.
• Chain of 3-Muramic acid.

B. Heteropolysaccharide:

• Contain two or more different kinds of monomeric units.
• Provide extracellular support to organism.

I. Glycosaminoglycans:

• Are linear polymers of repeated disaccharides and in most cases hexosamine.
• Are strongly acidic. Eg: Hyalauronic acid.

a. Hyalauronic acid

• Is linear polymer of glucuronic acid and N-Acetylglucosamine.
• There is no sulphate ester.