Question

Starch and cellulose are both produced by plants, yet one is easily digested by animals and the other is not. Discuss the differences in the structures of these two molecules and how this may impact whether they can be digested.

Answer 1

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.