Contrast the structure and function of starch with those of cellulose in plant cells?

Answer 1

Starch and Cellulose are both built on the same building block, Glucose, but are arranged differently. Because of this, they exhibit some different properties. Most importantly, the human body is capable of digesting starch, but not cellulose.

Answer 2

Starch tests positive with Iodine (blue black) as due to the helical shape of amylose (a constituent of starch) it can form poly-iodide with iodine to give a positive result. Cellulose has straight chains that are joined by cross links and H bonds to form bundles, resulting in a negative result with iodine.

Answer 3

Starch is a storage carbohydrate made of glucose monomers that are used for cellular fuel. The glucose

monomers in amylose are joined by 1-4 linkages. Amylopectin, a branched polymer, has 1-4 linkages

at its straight points and 1-6 linkages at branch points. All the glucose monomers in starch are in the

a configuration.

Cellulose is a building material found in plant cell walls. It is also made of glucose monomers, but its

glycosidic linkages are different from those of starch. The glucose monomers of cellulose are all in the

b configuration, making every other glucose monomer upside down in relation to the others. The

molecules can form hydrogen bonds with other parallel cellulose molecules. This property allows for

the formation of the strong fibers found in plant cell walls.

Answer 4

Starch is a polysaccharide made of glucose units that stores energy in plant cells, while cellulose is also a polysaccharide made of glucose units but provides structural support in plant cell walls. The glucose units in starch are linked by alpha-glycosidic bonds, allowing for easy digestion, while cellulose is linked by beta-glycosidic bonds, making it indigestible by most organisms. This structural difference gives starch a helical shape, while cellulose forms linear chains.