Question

Cellulose is made of
(a) Unbranched chain of glucose molecules linked by α – 1,6 glycosidic bonds
(b) Unbranched chain of glucose molecules linked by β – 1,4 glycosidic bonds
(c) Branched-chain of glucose molecules having α – 1,6 glycosidic bonds at the site of branching
(d) Branched-chain of glucose molecules with α – 1,6 glycosidic bonds in the straight-chain and β – 1,4 linked bonds at the site of branching

Answer 1

Hint: Cellulose, a structural carbohydrate is a linear homopolymer formed from repeating units of D-glucose, present in the beta conformation linked by glycosidic bonds. It is an abundant carbohydrate.

Complete answer:
The cellulose molecule is a linear, unbranched homopolysaccharide, consisting of 10,000 to 15,000 D-glucose units in β configuration linked by (β-1,4) glycosidic bonds.

Cellulose is a fibrous, tough, water-insoluble substance. It is present in the cell walls of plants, specially in stalks, stems, trunks, and all the woody portions of the plant body. Much of the mass of wood is from Cellulose.
Most animals are incapable to use cellulose as a fuel source, because they lack an enzyme to hydrolyze the β-1,4 linkages. In the animal kingdom, Termites are known to readily digest cellulose (and therefore wood) , because their intestinal tract harbors Trichonympha, a symbiotic microorganism that secretes cellulase, which hydrolyzes the β-1,4 linkages. Wood-rot fungi and bacteria can produce cellulase.
So, the correct answer is ‘Unbranched chain of glucose molecules linked by β-1,4 glycosidic bonds’.

Note:
- Cellulose is the primary structural carbohydrate in plants.
- Cellulose is indigestible by human beings.
- Cellulose is used in the paper industry and the textile industry.
- Cotton is almost pure cellulose.