Carbohydrates are sugar or hydrates of carbon in which the ratio of carbon to hydrogen to oxygen is 1:2:1 with empirical formula (CH, O). On the structural basis carbohydrates arte polyhydroxy aldehydes or ketones of substances that yield such compounds on hydrolysis.
These are most important biological molecule that are energy rich in nature and serve as principal energy resources and structural component of protoplasm and the cell.
Generally, carbohydrates are white, solid sparingly soluble in organic liquids but except for certain polysaccharides, soluble in water.
Carbohydrates are classified according to the number of simple sugar monomer units present in the molecule.
These are simple sugars having one sugar molecule. These are colorless, crystalline compounds with sweet taste.
Example: Glucose, fructose, galactose etc.
Each molecule contains two monosaccharide units. These are abundantly occurring in nature. These are colorless or white crystalline or amorphous solids soluble in water, sweeter than monosaccharides.
Example: Lactose, maltose, sucrose etc.
Polysaccharides: Comp0lex carbohydrates consisting of many monomer sugar units. These are insoluble in water, source of storage energy, and serve as reserve food.
Example: Starch, Cellulose, Glycogen etc.