Carbohydrates are the important organic molecules in lving organisms. They form the principal source of energy for the body. They are generally called saccharides or compounds containg sugar. Carbohydrates include a number of micro and macro molecules. Important micromolecules are monosaccharides and oligosaccharides.Â
Monosaccharides are simple sugars which cannot be further hydrolysed into simpler forms. These monosaccharides are the simplest carbohydrates, which contain free aldehyde (-CHO) and ketone (>C=O) groups, with two or more hydroxyl (-OH) groups with a general formula of Cn(H2O)n. Generally they are composed of 3-7 carbon atoms. Depending upon the number of carbon atoms they are of different types.Â
Pentose and hexose are biologically important Monosaccharides. Riboses and deoxyriboses are pentose sugars. Ribose is the components of RNA and ATP.
Deoxyribosoe occurs in DNA. Common hexoses include glucose, fructose and galactose. Glucose is the most importamt sugar occuring in animals. It is commoly called grape sugar or dextrose. Fructose or fruit sugar is found abundantly in fruits. Galactose is the sugar found in milk. Xylose (Wood sugar) is a sugar first isolated from wood, and named for it.