Classification of Carbohydrates

Carbohydrates are classified into three major groups based on their product of hydrolysis. Monosaccharides are the simple sugars that cannot be hydrolysed into any smaller carbohydrate unit; oligosaccharides yield a small number (typically two to ten) of monosaccharide units on hydrolysis, of which disaccharides -- yielding exactly two monosaccharide units -- are by far the most common and biologically important class; and polysaccharides yield a very large number of monosaccharide units on hydrolysis and are not sweet-tasting, which is why they are sometimes called non-sugars.

Monosaccharides are themselves classified along two independent axes. The first is the nature of the carbonyl group: a monosaccharide whose carbonyl group is an aldehyde is called an aldose, and one whose carbonyl group is a ketone is called a ketose. The second axis is the number of carbon atoms in the chain, which generates the family names triose (3 carbons), tetrose (4), pentose (5), hexose (6), and so on up to about eight carbons for the largest naturally occurring monosaccharides. Combining the two axes gives compound names such as aldohexose (a six-carbon aldehyde sugar, e.g. glucose) and ketohexose (a six-carbon ketone …