Question

based on figure 1, which of the following best compares the atomic structures of starch and cellulose? responses

Answer 1

The key structural difference between starch and cellulose is the type of glycosidic linkages; starch has α-1,4 and α-1,6 linkages allowing for a more branched and less rigid structure, while cellulose has β-1,4 linkages resulting in a linear, rigid structure that contributes to plant cell wall integrity and is indigestible by humans.

Step-by-step explanation:

The structural difference between starch and cellulose lies in the type of glycosidic linkages and the arrangement of glucose units. Starch consists of α-1,4 glycosidic linkages in its amylose component and α-1,4 and α-1,6 glycosidic linkages in its amylopectin component, which allow it to be less rigid and more easily digested by humans. On the other hand, cellulose is composed of β-1,4 glycosidic linkages that result in a linear, fibrous structure. This difference is significant because it accounts for the inability of human digestive enzymes to break down cellulose, making it a dietary fiber rather than a nutrient. Additionally, the presence of crosslinks in cellulose contributes to its rigidity, which is essential for the structural integrity of plant cell walls. These biochemical distinctions are crucial, as they determine how these polysaccharides function in biological processes and how they are utilized in various industries.

Answer 2

Starch and cellulose both consist of glucose monomers, but differ in their glycosidic linkages; cellulose has β-1,4 linkages forming rigid structures, while starch has α-1,4 and α-1,6 linkages resulting in a helical, less rigid form.

Step-by-step explanation:

The atomic structures of starch and cellulose are different which gives them distinct physical properties. The main structural difference lies in the type of glycosidic linkages; cellulose has β-1,4 glycosidic linkages that contribute to its rigidity, allow it to form crosslinks, and create a linear chain. In contrast, starch has α-1,4 and α-1,6 glycosidic linkages, which result in a less rigid structure without the tight crosslinks present in cellulose.

Additionally, starch molecules like amylose exhibit a helical structure, which is capable of trapping iodine molecules, resulting in a dark blue color when iodine contacts starch. This structural difference is important as it affects the biochemical reactions they undergo, with enzymes that can hydrolyze starch being unable to act on cellulose, and vice versa.

While starch, found in plants, serves primarily as an energy store, cellulose is a crucial structural component of plant cell walls. The biochemical distinction between these two polymers of glucose prevents plants from breaking down their structural components when the demand for energy increases.