4.0 Polysaccharides

  Biomolecules

• $(C_6H_{10}O_5)_n$

• A polymer of $\alpha$-Glucose and consists of two structurally different polysaccharides, Amylose ($20\%$ of starch) and Amylopectin ($80\%$ of starch).

• Amylose is water soluble component and a long unbranched chain joined by $\alpha$-glycosidic linkages between $C-1$ of one glucose unit and $C-4$ of the next glucose unit.

• Amylopectin is insoluble in water and a branched chain polymer of $\alpha$-$D$-Glucose units in which chain is formed by $C1-C4$ glycosidic linkage whereas branching occurs by $C1-C6$ glycosidic linkage.

Cellulose:

• It is the main structural material of plants and the constituent of cell wall of plant cells.

• It is a straight chain polysaccharide composed of $\beta$-$D$-glucose units joined by glycosidic linkage between $C1$ of one glucose unit and $C4$ of next glucose unit.

Glycogen:

• The carbohydrates stored in animal body are glycogens.

• Structure is similar to amylopectin and is more highly branched.