Name: Important Sources of Vitamins
Uploaded: 2019-07-19
Duration: 2 min 57 s
Description: Vitamins are essential for several biochemical reactions and the development of the body. This video describes their sources, types based on their solubility...

Question

What are the monomer units of starch and cellulose?

Accepted Answer

Starch is the main storage polysaccharide of plants. It is also known as amylum with the general formula ${(C_{6} H_{10} O_{5})}_{n}$ . It is a non-reducing sugar and is not readily oxidize as reducing sugar. Therefore, it is more useful for preserving foods such as jams, jellies, etc. It is a polymer of $α$ -glucose. The high content of starch is found in cereals, roots, rubbers, and some vegetables. It is hydrolyzed to glucose by enzyme amylase(present in saliva). It mainly contains two components- amylose $(15 - 20 %)$ and amylopectin $(80 - 85 %)$ . Amylose is the linear polymer of $α - D - glucose$ whereas amylopectin is a highly branched chain polymer of $α - D - glucose$ .

Fig- Structure of starch

Cellulose is a carbohydrate mainly found in wood and the most important structural component of the cell wall of plants. It is a colourless amorphous solid which decomposes on heating. It does not reduce Tollen’s reagent and Fehling’s solution. The structure of cellulose is a straight-chain polysaccharide composed of only $β - D -$ glucose units which are joined by glycosidic linkage.

Fig- Structure of cellulose

Therefore, the monomer units of starch and cellulose are $α - D - glucose and β - D - glucose$ respectively.

What are the monomer units of starch and cellulose?

Important Questions on Biomolecules

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