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 is a branched polymer while cellulose is a straight chain. Starch is digested using amylase which is present in animals. Some animals lacked the enzymes that are needed to digest cellulose. However, other animals can digest it with the use of symbiotic microorganisms located in their guts.

Answer 2

Answer:

Starch has alpha 1,4 linkages to join glucose while cellulose have beta 1,4 linkage to join the glucose molecules together.  The different bonding pattern makes starch digestible while cellular indigestible.

Explanation:

Starch is a polymer of glucose with alpha 1,4 glycosidic linkage and some alpha 1,6 glycosidic linkages. These alpha bonds are digestible by enzymes present in the human digestive tract. The glycogen (storage sugar of human) also have alpha glycosidic linkages.  

On the other hand, cellulose is a polymer of glucose with beta 1,4 glycosidic linkages. These beta glycosidic linkages can not be digested by enzymes of the human digestive system.