Starch and Cellulose (4.9)

Question 1

Desribe how beta glucose molecules join together to form cellulose molecules

Answer 1

Adjacent beta glucose molecules undergo a condensation reaction between the carbon 1 of one molecule and carbon 4 of the other. This means every other glucose is inverted.

Question 2

Describe how adjacent cellulose molecules join to form a cellulose microfibril.

Answer 2

Hydrogen bonds between cellulose molecule chains form leading to the formation of cellulose microfibril

Question 3

Describe the role of pectins and hemicelluloses in the cell wall structure.

Answer 3

It functions incell adhesion and wall hydration, and pectin crosslinking influences wall porosity and plant morphogenesis. Whereas, hemicelluloses contribute to strengthening the cell wall by interaction with cellulose and, in some walls, with lignin.

Question 4

Compare and contrast the structure of cellulose and starch.

Answer 4

Starch involves alpha glucose whereas cellulose involves beta glucose. Starch also contains 1,6glycosidic bondswhereas cellulose only contains 1,4 glycosidic bonds. Starch forms a coiled/helical structure whereas cellulose forms a linear fibre.