Image:Lactose.svg|thumb|right|310px|Lactose is a disaccharide found in milk. It consists of a molecule of D-galactose and a molecule of D-glucose bonded by a-1-4 glycosidic linkage. A carbohydrate is an organic compound with general formula C_m(H₂O)_n, that is, consisting only of carbon, hydrogen and oxygen, the last two in the 2:1 atom ratio. Carbohydrates can be viewed as hydrates of carbon, hence their name. The term is most commonly used in biochemistry, where it is essentially a synonym of saccharide, a large family of natural carbohydrates that fill numerous roles in living things, such as the storage and transport of energy (e.g., starch, glycogen), structural components (e.g., cellulose in plants and chitin in arthropods), and as components of coenzymes (e.g., ATP, FAD, and NAD) and the backbone of genetic molecules (e.g., RNA and DNA). This word comes from the Greek σάκχαρον (sákcharon), meaning "sugar". Saccharides and their derivatives include many other important biomolecules that play key roles in the immune system, fertilization, pathogenesis, blood clotting, and development. In food science and in many informal contexts, the term carbohydrate often means any food that is particularly rich in starch (such as cereals, bread and pasta) or sugar (such as candy, jams and desserts). While the scientific nomenclature of carbohydrates is complex, the names of carbohydrates very often end in the suffix -ose.

[Last contributor : Robert.Allen , Content under LGPL licence]