Cellulose: Difference between revisions

==Structure==

Glucose, the building block of cellulose and starch, can form six-membered rings with two distinct stereoisomers called the alpha and beta anomer. The only difference between alpha and beta glucose is at carbon C1. The [[disaccharides|disaccharide]] cellobiose  (reload <scene name='82/824000/Cellobiose/4'>initial scene</scene>) is a breakdown product of cellulose which shows the beta 1,4 linkage between two glucose molecules also present in cellulose. "beta 1,4" refers to a glycosidic link between the anomeric carbon (<jmol><jmolLink><script> spin off; select 823.C1; selectionHalos ON; delay 0.5;selectionHalos OFF;</script><text>☼</text></jmolLink> </jmol>) in beta configuration of one glucose molecule with carbon 4 (<jmol><jmolLink><script> select 823.C4'; selectionHalos ON; delay 0.5;selectionHalos OFF;</script><text>☼</text></jmolLink> </jmol>) of the other glucose molecule. In contrast, starches (specifically the linear form [[amylose]]) can be broken down to [[disaccharides|maltose]], a stereoisomer of cellobiose showing an alpha 1,4 linkage. Thus, it is the type of glycosidic linkage that distinguishes cellulose from starches at the molecular level.