Fructose is a monosaccharide. It contains six carbons and a ketone group, classifying it as a ketohexose. Fructose is present as the free sugar in many fruits, and it is also derived from hydrolysis of sucrose (see Figure 13.12).

Fructose is acted on by the enzyme fructokinase to produce fructose-1-phosphate.

Fructose (from sucrose) is also involved in dextran synthesis in bacteria.