Chapter 2 - The Chemical Level of Organization - Checkpoint - Page 48: 16

Carbohydrates are organic compounds made of molecules of atoms of carbon, hydrogen and oxygen, the carbon and hydrogen atoms usually being present in a ratio of 2: 1, carbon to hydogen. The layman often divides carbohydrates into two classes simple sugars and complec sugars, but for scientific purposes this is not a very useful classification. A threefold categorization of monosaccharides, disacchsrides and polysaccharides is usually adequte for college biology though it may not be detailed enough for organic chemists Monosaccharides are the simplest form of carbohydrates. The molecules of these compounds are single (non-polymeric) molecules of three to seven carbon atoms in a straight or cyclic configuration. The most well -now monosaccharides are trioses (3Cs), tetroses(4Cs) pentoses(5 Cs), hexoses (6Cs) and heptoses (7 Cs) andoctoses (8Cs). Hexoses form some of our most useful biological monosaccharides such as glucose (blood sugar , also in grapes and honey), lactose ( milk sugar) and fructose (fruit sugar). The pentoses ribose and deox-ribose) are of great physiolgical importance because of their part in the structure of the nucleic acids ( RNA and DNA). Disaccharides are are carbohydrates with molecules made up of polymers of two monosaccharide molecules . Well-known examples of sucrose are cane sugar and beet sugar. Each sucrose molecue hydrolyses to give one molecule of glucose and one of fructose If a carbohydrate molecule hydrolyses to give more than two monosaccharide molecules it is classified as a polysaccharide. Not all organic chemists agree on this categorization criterion.. Some scientists only include in this class, carbohydrates with moleules that are polymers of more than nine monosaccharide molecules. Well known polysaccharides are starch, glycogen, dextrin, inulin, cellulose, hyalauronic acid. chondroitin sulfate, heparin, and keratin sulfate.

Carbohydrates are organic substacnes comprised of molecules with the atoms carbon, hydrogen and and oxy gen . The general formula is usually written CnH2nOn, where n is usullay 2 to 7. A useful classification for students is to divide carbohydrates into three classes viz., monosaccharides, oligosaccharides and polysaccharides. in this grouping, disacccharides are subsumed under oligosaccharides. Monosaccharides have three to 8 carbon in the molecular backbone or the ring of the structure.A monosaccharide cannot hydrolyse to give several types of molecules. Common monosaccharides are glucose, fructose and galactose. Oligosaccharides arr carbohydrates that hydrolyse to give two to nine types of monosaccharide molecules.This group includes disaccharides Polysaccharides are very complex carbohydrateswhich hydrolyse to give more than ten monosaccharide molecules