Chapter 24.2, Problem 13LC

Interpretation Introduction

Interpretation: The difference between starch and cellulose is to be explained.

Concept introduction: Polysaccharides are long polymer chains made of joining monosaccharide molecules. Starch and cellulose are an example of polysaccharides.

Answer to Problem 13LC

The linkages between the glucose units distinguish cellulose from starch. Cellulose is composed of beta-glucose linkage, whereas starch is composed of alpha-glucose linkage.

Explanation of Solution

Both cellulose and starch contain the same number of glucose repeat units but have different properties. The formation of starch requires alpha glucose, while the formation of cellulose requires beta glucose.

In comparison, cellulose only has $\text{1,4-}$ glycosidic linkages, but starch has $\text{1,6-}$ glycosidic bonds. The structure of starch is coiled or helical, while the structure of cellulose is a linear fiber.

Conclusion

The linkages between the glucose units distinguish cellulose from starch. Cellulose is composed of beta-glucose linkage, whereas starch is composed of alpha-glucose linkage.