Maltose, a disaccharide. Two molecules of glucose are linked by an α-1,4-glycosidic bond to form the disaccharide maltose. The angles in the bonds to the central oxygen atom do not denote carbon atoms. The angles are added only for ease of illustration. The glucose molecule on the right is capable of assuming the open-chain form, which can act as a reducing agent. The glucose molecule on the left cannot assume the open-chain form, because the C-1 carbon atom is bound to another molecule.