Carbohydrate

Question 1

Aldoses and Ketoses

Answer 1

Aldoses: Sugars with aldehyde at the C-1 position
Ketoses: Sugars with ketones at the C-2 position

Question 2

L-sugars

D-sugars

Answer 2

L-sugars: have the highest-numbered chiral hydroxyl group on the left side of the sugar
D-sugar: have the highest-numbered chiral hydroxyl group on the right side of the sugar

L- and D-sugars of the same name are enantiomers

Question 3

Epimers

Answer 3

Sugars that differ at only one chiral center

Question 4

Sugars can undergo intramolecular reactions that form rings

Answer 4

Pyranose rings: six-membered sugar rings
Furanose rings: five-membered rings

C-1 becomes chiral when a ring is formed ; this newly chiral atom is known as the anomeric carbon

Question 5

Anomers

Answer 5

Cyclic stereoisomers that differ about the new chiral carbon.

Alpha-anomer: has the -OH group of C-1 trans to the CH2OH substituent (pointing down)
Beta-anomer: has the -OH group of C-1 cis to the CH2OH substituent (pointing up)

Question 6

Mutarotation

Answer 6

The interconversion between the alpha and beta anomers via ring opening and reclosing

Question 7

Polysaccharides

Answer 7

Cellulose is a chain of glucose with 1,4’-beta-glycosidic bonds.
Starch and glycogen have mostly 1,4’-alpha-glycosidic bonds