Cellulose (C₆H₁₀O₅)_n

Sources : Cellulose occurs exclusively in plants and is the most abundant organic substance in the plant kingdom. It is a predominant constituent of the cell wall of the plant cell. It is present in wood, cotton clothes, jute, cotton, etc. in wood, it is present 50 %, in dry grasses, it is 40 – 45 %, injure 60 – 65 %, in cotton 90 – 95 %, in cotton clothes 90 % cellulose and rest in fats and waxes.

Structure: Cellulose is composed of β - D - glucose units linked by (1 → 4) glycosidic bonds. The X - ray analysis has shown that there are large linear chains of β - D (+) glucose molecules lying side by side in the form of bundles held together by H - bonding in the neighboring hydroxyl groups. In each linear chain, the D(+) glucose unit are attached to each other by C₁ to C₄ bonds through β  – glycosidic linkages as shown below.

(ii) Starch (C₆H₁₀O₅)_n 

Sources : Starch is a major source of carbohydrates which are very much essential to the human body since they supply energy to the body. It occurs as granules mainly in seeds, fruits, tubers, and also in the roots of plants. The chief commercial sources of starch are wheat, maize, rice, potatoes etc.

Structure : Starch consists of two polysaccharide components. They are

(a) Amylose 15% - 20% soluble in water.

(b) Amylopectin (90% - 90%) insoluble in water.