Question

Define the following with an example of polysaccharides.

Answer 1

We know that polysaccharide is a type of complex carbohydrate. Polysaccharides are formed by a chain of monosaccharides and are very large in size. The monosaccharides are linked by glycosidic bonds to form a polysaccharide.

Complete step by step answer:
We know that the long chains of monosaccharides that are linked by glycosidic bonds are known as polysaccharides. Polysaccharides are complex carbohydrates.
The glycosidic bonds have oxygen molecules that bridge the two carbon rings. The glycosidic bond is formed when carbon of one molecule loses the hydroxyl group, and the hydroxyl group of another monosaccharide loses a hydrogen atom. Two atoms of hydrogen and one atom of oxygen is lost, the glycosidic bond formation is a dehydration reaction.
Many sugar molecules come together and form a large molecule of polysaccharide. Polysaccharides are also known as glycans.
There are two types of polysaccharides: homopolysaccharides and heteropolysaccharides.

1. Homopolysaccharides: The polysaccharides formed by a single type of monosaccharides are known as homopolysaccharides. Examples are starch, cellulose, etc.
2. Heteropolysaccharides: The polysaccharides formed by more than one type of monosaccharides are known as heteropolysaccharides. Examples are heparin, hyaluronic acid, etc.
   The most common example of a polysaccharide is starch. The molecular formula for starch is ${\left( {{{\text{C}}_{\text{6}}}{{\text{H}}_{{\text{10}}}}{{\text{O}}_{\text{5}}}} \right)_n}$
   Starch is found in all photosynthetic plants mostly in the roots and seeds. When plants synthesize glucose, the excess glucose is stored in the form of starch. Starch consists of a linked glucose molecule and thus, starch is also known as glucan.
   Other examples of polysaccharides are chondroitin sulphate, glycogen.

Note: Only three polysaccharides are available naturally. They are starch, glycogen and cellulose. Glycogen and cellulose both contain D-glucose units. The main function of polysaccharide is to store energy in organisms. Polysaccharides provide support to the cell wall because the polysaccharide cellulose is the main constituent of cell wall.