Starch and cellulose have the same substance but different structures. They are both polysaccharides. The basic unit of a polysaccharide is the glucose. Glucose, which contains carbon, hydrogen, and oxygen, have two forms. The alpha-glucose with an alcohol group attached to carbon 1 is down and the beta-glucose with the alcohol group attached to carbon 1 is up. Starch is the alpha-glucose while cellulose is the beta-glucose. Starches are linked into a straight chain whereas the cellulose are connected like a pile of stack paper. When the human body eats starch, it can digest the starch but not the cellulose because it has no enzyme that can break it down.