Definition of Ketose

A ketose is defined as a monosaccharide that has only one ketone group as a functional group in each molecule. All monosaccharides having ketone as their functional group are reducing in nature. This is because they can tautomerize into aldose sugars. The simplest example of a ketose is dihydroxyacetone which is an isomer of glyceraldehyde and they are interconvertible into each other by redox reactions.


The ketose sugars have 3 or more carbon atoms present in their structure. They are named as trioses, tetroses, pentoses, hexoses, and so forth. Those ketose sugars that are being bound into some kind of glycosides such as fructose, a six-carbon ketose sugar, moiety of sucrose become non-reducing sugars.

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