CarbohydratesStructure and Biological Function

Carbohydrates are often known as sugars, they are the staff of life for most organisms. They are the most abundant class of biomolecules in nature, based on mass.
Carbohydrates are also known as saccharides, in Greek sakcharon mean sugar or sweetness.

They are widely distributed molecules in plant ans animal tissues. In plants, and arthropods, carbohydrates from the skeletal structures, they also serve as food reserves in plants and animals. They are important energy source required for various metabolic activities, the energy is derived by oxidation. Plants are richer in carbohydrates than animals.
Carbohydrate is an organic compound, it comprises of only oxygen, carbon and hydrogen. The oxygen: hydrogen ratio is usually is 2:1. The empirical formula being Cm(H2O)n (where m can be different from n). Carbohydrates are hydrates of carbon, technically they are polyhydroxy aldehydes and ketones. Carbohydrates are also known as saccharides, the word saccharide comes from Greek word sakkron which means sugar.
Monosaccharides are often called simple sugars, these are compound which possess a free aldehyde or ketone group. They are the simplest sugars and cannot be hydrolyzed. The general formula is Cn(H2O)n or CnH2nOn. The monosaccharides are subdivided into tiroses, tertrose, pentoses, hexoses, heptoses etc., and also as aldoses or ketoses depending upon whether they contian aldehyde or ketone group.
Oligosaccharides are compound sugars that yield 2 to 10 molecules of the same or different monosaccharides on hydrolysis.
Oligosaccharides yielding 2 molecules of monosaccharides on hydrolysis is known as a disaccharide, and the ones yielding 3 or 4 monosaccharides are known as trisaccharides and tetrasaccharides respectively and so on. The general formula of disaccharides is Cn(H2O)n-1 and that of trisaccharides is Cn(H2O)n-2 and so on.
Polysaccharides are compound sugars and yield more than 10 molecules of monosaccharides on hydrolysis. They re further classified depending on the type of molecules produced as a result of hydrolysis. They may be homopolysaccharides i.e, monosaccharides of the same type or heteropolysaccharides i.e., monosaccharides of different types. The general formula is (C6H10O5)x.