Carbohydrates

Question 1

Draw the Fischer projection of D-glucose

Answer 1

See book

Question 2

What anomer forms when the OH attacks from above in the cyclization of D-glycose?

Answer 2

The Beta anomer (the OH on the anomeric carbon and the 6:th carbon are on the same side of the ring plane, in this case above the ring).

Question 3

What anomer forms when the OH attacks from below in the cyclization of D-glycose?

Answer 3

The alpha anomer (the OH on the anomeric carbon and the 6:th carbon are on different sides of the ring plane, is this case the 6:th carbon is up and the OH is down).

Question 4

Describe the structure and properties of amylose.

Answer 4

Amylose is a starch and has a main function of energy storage. Due to the alpha linkage, steric hindrance and H bonding between monomers, amylose forms tightly coiled helices. It is abundant in plants and is unbranched.

Question 5

Describe the structure and properties of cellulose.

Answer 5

Cellulose has many similarities to amylose; it is an unbranched homopolysaccharide that is abundant in plants. However, unlike amylose, cellulose has more of a structural function due to its tensile strength and flexibility. It has a planar instead of a coiled structure. This allows it to maximize the amount of H-bonds present in between the monomers. The monomers are linked together via a beta 1–>4 glycosidic bond, which is another reason it can partake in a planar structure.