carbohydrates : introduction and function

introduction

carbohydrates are the most abundant class of organic molecules found in nature and biological system. they contains C, H and O having basic molecular formula (CH20)n. carbohydrates means “hydrates of carbon”

they are the basic molecules of life, many plants and animals contain large amount of them as reserve food material. green algae, photosynthetic bacteria and green plant contain chlorophyll and hence are able to synthesize carbohydrates from carbon dioxide and water by the process of photosynthesis .

they are metabolic precursors for almost all other biomolecules . breakdown of carbohydrates provide the energy by the process of respiration that is important process for animals and non photosynthetic bacteria

Normally they are classified as monosaccharide (one carbohydrate unite) e.g. glucose , fructose , disaccharide (two `carbohydrate unite) e.g. lactose , sucrose , oligosaccharide (3-10 carbohydrate unite)e.g. Raffinose and polysaccharide (>10 carbohydrate unite) e.g. starch , glycogen.

Monosaccharide units are generally joined by glycosidic bond and forms disaccharide , oligosaccharide and polysaccharide.

Carbohydrates are defined as polyhydroxy aldehydes or ketones or compounds which produces them on hydrolysis. Those carbohydrates that are soluble in water and sweet in taste are termed as ‘sugars’

Functions of carbohydrates

1. They take part in number of functions in living system apart from providing energy, they are structural components of tissues, regulate metabolism of fat, functions of the protein and digestive tract
2. They are the storehouse of energy in animals . breakdown of carbohydrates provides about 60% of the total energy requirement of humans. Oxidation of 1 gram of carbohydrates provides around 4 calories of energy. Energy needed by the body tissues is supplied by glucose. Glucose is the sole sources of energy for brain and other nervous tissues they are stored in the body in the form of glycogen
3. They are the most important components of some structural component of some structural materials of living system.monosaccharide are important constituents of nucleic acids, coenzymes , flavoproteins and blood group substances
4. they are essential for metabolism of fat
5. When available in sufficient amount they are metabolized for energy requirements of the body. Thus it spares protein for formation of the tissues.
6. Indigestible substance like cellulose provides bulk of roughage and decreases the absorption of glucose and cholesterol and it increases the bulk of feces.
7. Glycosides – steroid hormones
8. Galactolipids – nervous tissues
9. Heparin prevents clotting of blood
10. Vitamin c is related to sugars

they are also utilized as raw material by several industries like paper , textile , alcohol and plastics