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carbohydrate, 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 (CH2O)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 Cn(H2O)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.
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A class of simple sugars containing a chain of 3–10 carbon atoms in the molecule, known as polyhydroxy aldehydes (aldoses) or ketones (ketoses). They are very soluble in water, sparingly soluble in ethanol, and insoluble in ether. The number of monosaccharides known is approximately 70, of which about 20 occur in nature. The remainder are synthetic. The existence of such a large number of compounds is due to the presence of asymmetric carbon atoms in the molecules. Aldohexoses, for example, which include the important sugar glucose, contain no less than four asymmetric atoms, each of which may be present in either d or l configuration. The number of stereoisomers rapidly increases with each additional asymmetric carbon atom.

A list of the best-known monosaccharides is given below:

Aldose monosaccharides having 8, 9, and 10 carbon atoms in their chains have been synthesized. See Carbohydrate

McGraw-Hill Concise Encyclopedia of Bioscience. © 2002 by The McGraw-Hill Companies, Inc.


A carbohydrate which cannot be hydrolyzed to a simpler carbohydrate; a polyhedric alcohol having reducing properties associated with an actual or potential aldehyde or ketone group; classified on the basis of the number of carbon atoms, as triose (3C), tetrose (4C), pentose (5C), and so on.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.


a simple sugar, such as glucose or fructose, that does not hydrolyse to yield other sugars
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005
References in periodicals archive ?
CDG patients are born with a genetic defect that hinders their ability to utilize certain monosaccharides in the production of glycoproteins.
mycrophylla were analyzed for the presence of alkaloids, saponins, tannins, phenols, amino acids, and monosaccharides.
Standard monosaccharides, 1,3,5-tri(2-pyridyl)-2,4,6-triazine (TPTZ), and 1,1-diphenyl-2-picrylhydrazyl (DPPH) were purchased from Sigma Chemical Co.
Lactic acid yield from fermentation of monosaccharide usually has a very high molecular weight (> 90%) [4].
The effect of this nonenzymatic alteration with four monosaccharides (glucose (G), mannose (M), arabinose (A), and rhamnose (R)) on the cell morphology and the direction of the differentiation was analyzed.
Determination of Molecular Mass and Analysis of Monosaccharide Composition of Polysaccharides
Galactose was the predominant monosaccharide in all conditions studied, with levels varying from 8.34 [+ or -] 1.4 g [L.sup.-1] (0.2 M 10 [min..sup.-1]) to 14.83 [+ or -] 1.02 g [L.sup.-1] (0.5 M 20 [min..sup.-1]).
In fact, when melibiose, which is a disaccharide having an acid-labile 1,6-glycosidic bond, was treated with methanol in the presence of hydrogen chloride under Fischer's conditions, the product was a mixture of monosaccharide derivatives as a result of glycosidic bond cleavage.
All isolates were able to assimilate D-xylose, a common feature in yeasts able to metabolize SBHH because this is the most abundant monosaccharide in hemicellulose [15].
Buttner, "The monosaccharide transporter(-like) gene family in Arabidopsis," FEBS Letters, vol.
Trifluoroacetic acid (TFA), dextrans, monosaccharide standards, dimethyl sulfoxide (DMSO), and lipopolysaccharide (LPS) were purchased from Aladdin Reagent Int.