In biochemistry, monosaccharides are carbohydrates in the form of simple sugars.

Monosaccharides, like disaccharides, are sweet, water soluble and crystalline.

Monosaccharides are classified by the number of carbon molecules they contain (triose, tetrose, pentose, hexose and heptose) and by the active group, which is either an aldehyde or a ketone. These are then combined, e.g. aldohexoses, ketotrioses.

Examples include the hexoses (glucose, fructose, and galactose) and pentoses (ribose, deoxyribose).


With a few notable exceptions (e.g. deoxyribose), they have the general formula: