Chapter 7: Carbohydrates

Question 1

Carbohydrates

Answer 1

aldehydes or ketones with at least two hydroxyl groups, or substances that yield such compounds on hydrolysis

Question 2

Monosaccharides

Answer 2

simple sugars, consisting of a single aldehyde or ketone unit.

Question 3

Example of Monosaccharides?

Answer 3

D-Glucose, D-Fructose, D-Ribose, D-Galactose

Question 4

Disaccharides

Answer 4

oligosaccharide with two monosaccharide units

Question 5

Example of Disaccharides?

Answer 5

Maltose, Sucrose, Lactose

Question 6

Polysaccharide

Answer 6

sugar polymer with 10+ monosaccharide units

Question 7

Example of Polysaccharide?

Answer 7

Starch, Glycogen, Cellulose

Question 8

Structure of Monosaccharides

Answer 8

• are either aldehydes or ketones with at least two or more hydroxyl groups
• often have 1+ stereo centers (chiral carbons) creating many possible stereoisomers

Question 9

Aldoses

Answer 9

monosaccharides that contain a terminal carbonyl group

Question 10

Ketoses

Answer 10

monosaccharides that contain an internal carbonyl group

Question 11

What is the smallest aldose?

Answer 11

Glyceraldehyde

Question 12

Labeling Fischer Projections

Answer 12

configuration of the chiral carbon furthest from the aldehyde is labeled as D (OH to the right) or L (OH to the left)

Question 13

Monosaccharide Variations

Answer 13

• vary in the number of carbons
  - Ex: 3 carbon = trioses
• most common monosaccharides contain 5-6 carbons: pentoses and Hexoses
• number carbons starting on the side closest to the carbonyl group (aldehyde or ketone)

Question 14

What are epimers?

Answer 14

sugars that vary at one chiral center
- ex: OH is on the right vs OH on the left of Fischer projection

Question 15

Cyclic Sugars

Answer 15

• monosaccharides are more stable as cyclic structures vs open-chain (exists as equilibrium between the two)

Question 16

Hemiacetal

Answer 16

Ring-closure results from an attack by a hydroxyl group on the carbonyl carbon to form a cyclic hemiacetal

Question 17

Anomeric Carbon

Answer 17

the new chiral center of a cyclic hemiacetal

Question 18

Alpha Anomeric Carbon Vs Beta Anomeric Carbon

Answer 18

If the ring closure/hemiacetal formation results form a frontside attack, the anomeric carbon is said to be alpha. If it is a backside attack, the anomeric carbon is said to be beta.

Question 19

Pyranoses

Answer 19

6-membered rings

Question 20

Furanoses

Answer 20

5-membered rings

Question 21

What is the relation between
a-D-G-Glucopyranose and b-D-Glucopyranose?

Answer 21

they are anomers

Question 22

Glycosidic Linkage

Answer 22

An O-glycosidic linkage covalently links two monosaccharide units together.