Question

Both starch and cellulose are made by stringing together many glucose molecules. However, while starch is easily digested by humans, cellulose is indigestible. The starch polysaccharide has bonds occurring below the sugar rings, while the bonds in cellulose alternate above the ring and below the next ring. How can you explain humans' inability to digest cellulose?

Answer 1

Answer:

The monomeric unit of both polymers, cellulose, and starch is glucose. Also, both are associated with the plant system.

Explanation:

Numerous glucose subunits joined together by glycosidic bond leads to the formation of the polymeric compound known as starch.The conversion of the glucose molecule to starch on the cost of ATP or energy molecule is the process carried out to convert it into a storage form in case of animals. It also acts as an energy store in the case of the plant system.  

Cellulose serves the function of cell wall formation and the starch acts as a storage form of energy. The repeating glucose subunit of cellulose orients in a single direction in contrast to the starch that accounts for the rotation of successive glucose subunit.  

Despite of some similarity between the above mentioned polysaccharides, the cellulose cannot be digested by the humans because of the absence of the cellulase enzyme in the human body. Also, chemical digestion of cellulose is called thermolysis that takes requires temperature above 400 degree Celsius.