What are the functions of carbohydrates in living organisms?

Explanation

Carbohydrates have a number of different functions in the living organisms.
(i) Structural matrial : Polysaccharides such as cellulose act as chief structural material for the cell walls in all plants.
(ii) Reserve food materials : Some polysaccharides form an ideal storage product in the form of reserve food materials. For example, starch is a major food reserve in plants. In seeds, starch reserve act as a reserve food material for the tiny plant, till it is capable of making its own food by photosynthesis. Similarly in animals glycogen acts as `epsi` reserve food material. It is particularly abundant in liver cells. It is ready source of glucose for the blood.
(iii) As a source of energy: Carbohydrates such as glucose, starch, glycogen etc., provide energy for the functioning of living organisms. In the living systems polysaccharides like starch and glycogen are first hydrolysed by enzymes to glucose. These simple monosaccharides are then transported to the various cells where they are oxidised to carbon dioxide and water by a series of enzymes catalysed reactions. The energy released during the reaction provides the necessary bioenergy for the functioning of cells.
`C_6 H_(12) O_6 + O_2 to 6CO_2 + 6H_2 O + 2868 KJ`
(iv) In nucleic acids (RNA and DNA): Monosaccharides, like ribose and 2-deoxyribose are the essential components of RNA and DNA respecitively. Nucleic acids play an essential role in the transmission of hereditary characteristics and biosynthesis of proteins.
(v) In adenosine triphosphate (ATP) : Monosaccharide ribose is also present in adenos ine triphosphate (ATP). ATP molecules, are the currency of energy metabolism in a cell