polisahhariide

Polysaccharides are complex carbohydrates composed of long chains of monosaccharide units linked together by glycosidic bonds. They are one of the three main classes of carbohydrates, along with monosaccharides and disaccharides. Polysaccharides serve a variety of important functions in living organisms, including energy storage and structural support.

In plants, starch is a major storage polysaccharide. It is composed of repeating glucose units and can exist in two forms: amylose, a linear polymer, and amylopectin, a branched polymer. Glycogen serves a similar energy storage role in animals and fungi, also consisting of glucose units but with more extensive branching than amylopectin.

Cellulose is another crucial polysaccharide, providing structural integrity to plant cell walls. It is also a polymer of glucose, but the glycosidic linkages differ from those in starch, making it indigestible by most animals. Chitin is a structural polysaccharide found in the exoskeletons of arthropods and the cell walls of fungi, similar in structure and function to cellulose.

Other important polysaccharides include hyaluronic acid, a component of connective tissues, and agar, a gel-forming substance derived from algae used in microbiology and food industries. The specific arrangement and type of monosaccharide units, as well as the nature of the glycosidic linkages, determine the physical and chemical properties of each polysaccharide and its biological role.