Chapter 23, Problem 4RQ

Which monosaccharide do starches and cellulose have in common?

To determine

The monosaccharide which is common in the structure of starch and cellulose.

Answer to Problem 4RQ

The monosaccharide which is common in starch and cellulose is glucose.

Explanation of Solution

The starch is not a single compound; it is considered as a mixture of two components. The first component is water soluble and is named as amylose. The second component is water insoluble and is named as amylopectin.

Amylose is a liner polymer of glucose in which ${\text{C}}_1$ of one glucose unit is attached to ${\text{C}}_4$ of the other through glycoside linkage. However, amylopectin is a highly branched chain polymer of glucose. It consist of hundreds of short chains each containing $20-25$ glucose units.

The cellulose on the other hand is a biomolecule which is composed of $300-3000$ glucose units. The molecular mass of cellulose varies from $50000$ to $500000$.

Thus, the monosaccharide which is common in the structure of starch and cellulose is glucose.

Conclusion:

The monosaccharide which is common in the structure of starch and cellulose is glucose. As structure of starch contains a liner polymer and a highly branched polymer of glucose unit and that of cellulose also contains a linear condensation polymer of glucose units.