Carbohydrate
Related Category: Organic Chemistry
any member of a large class of chemical compounds that includes sugars, starches, cellulose, and related compounds. These compounds are produced naturally by green plants from carbon dioxide and water (see
photosynthesis). Carbohydrates are important as foods; they supply energy and are used in the production of fats. They are also used in various forms in industry and commerce. There are three main classes of carbohydrates. Monosaccharides are the simple sugars, e.g.,
fructose and
glucose; they have the general formula (CH
2O)
n, in which
n is an integer larger than 2. Disaccharides include
lactose,
maltose, and
sucrose. Upon hydrolysis, a disaccharide molecule yields two monosaccharide molecules. Most disaccharides have the general formula C
n(H
2O)
n−1, with
n larger than 5. Polysaccharides include such substances as
cellulose,
dextrin,
glycogen, and
starch; they are polymeric compounds made up of the simple sugars and can be hydrolyzed to yield simple sugars. The disaccharides are sometimes grouped with the simpler polysaccharides (usually those made up of three or four simple sugar units) to form a class of carbohydrates called the oligosaccharides.
