Fructose forms a five-membered ring when the hemiketal forms. The oxygen bonded to carbon #5 reacts with carbon #2 (yellow and blue halos, respectively, in Panel 2) to form the five-membered furanose ring. Panel 1 contains α-D-fructofuranose, one of the two anomers formed. The hydroxyl group on the anomeric carbon (blue halo) projects below the ring. Notice that carbon atoms 1 and 6 are not part of the ring. Rotate the structure of β-D-fructofuranose in Panel 3 so that it is positioned similarly to that in Panel 1 and observe how the hydroxyl group projects from the anomeric carbon. Like glucose fructose is a reducing sugar.