Kaplan Ch. 4 - Carbohydrate Structure And Function

Question 1

What do the names of sugars end in?

Answer 1

• ose

Question 2

What two functional groups are most common in sugars?

Answer 2

Aldehyde (= Aldose)

Ketone (=ketose)

Question 3

What is an epimer?

Answer 3

A sub class of disastereomers where the two molecules only differ in configuration at 1 chiral carbon.

Question 4

In formation of a cyclic carbohydrate:

1) what acts as the nucleophile?
2) what acts as the electrophile?
3) what is the anomeric carbon?

Answer 4

1) hydroxyl group in carbon 5
2) carbonyl carbon
3) once the carbonyl carbon is attacked by OH it becomes chiral, and is now called the anomeric carbon

Question 5

What is pyranose?

What is furanose?

Answer 5

Pyranose = 6 membered cyclic sugar
Furanose = 5 membered cyclic sugar

Question 6

Mutorotation

Answer 6

When sugars are placed in water they spontaneously open and close their ring structures and can these switch between alpha and beta anomers quite easily.

Question 7

What is a reducing sugar?

Answer 7

Any monosaccharide with a hemiacetal ring, names this way because they can be oxidized

Question 8

Lactone

Answer 8

Cyclic ester

Question 9

What is the tollen’s reagent rest?

Answer 9

This is a test to check for reducing sugars.

Uses Ag(NH3)2+ as oxidizing agent (this is thus reduced). Aldehyde I’m sugar is oxidized and reduces Ag+ to metallic silver.

Question 10

What is benedict’s test

Answer 10

This is also a test to check for reducing sugars.

The aldehyde group is oxidized and this is indicated by a red precipitate of Cu2O forming