Glucose

(CC) Image: David E. Volk
Different forms of glucose

Glucose is a hexose sugar molecule present in living organisms. It is a component of the disachharides sucrose, galactose and maltose, to name a few. Because it contains an aldehyde in the open chain structure, it is one of the aldose sugars. Glucose can cyclize to form five- and six-atom ring structures called glucofuranose and glucopyranose, respectively, as shown in the illustration.