Organic chemistry is the study of carbon compounds.
Compounds consisting of carbon are said to be organic. Although a cell is composed of seventy to ninety percent water, most of the rest of the cell contains carbon-based compounds. DNA, proteins, carbohydrates, and other molecules that distinguish living matter from inanimate material are composed of carbon atoms that are bonded to one another and to atoms of other elements. It is carbon that accounts for the endless diversity of biological molecules. The percentage of major elements of life-P, S, C, H, O and N are quite uniform from the individual to individual.