Carbohydrate Chemistry

Question 1

What are carbohydrates involved in?

Answer 1

Involved in cell communication

Tumour metastasis

Question 2

What is a carbohydrate?

Answer 2

Generic term for C=O containing organic molecules with hydroxyl OH groups
Carbohydrates are polymers of small sugars

Question 3

What is the generic formula?

Answer 3

Cn(H2O)n

Question 4

How do you name a carbohydrate?

Answer 4

1) position of C=O
2) number of carbons
3) stereochemistry

Question 5

What is D and L?

Answer 5

They describe stereochemistry

They are enantiomers of each other (mirror image)

Question 6

How do you determine D or L

Answer 6

Is the OH of the highest stereochemical centre facing the same way as D- glyceraldehyde? (Facing right)
Yes= D (right)
No= L (left)

Question 7

What is an epimer?

Answer 7

It is a diastereoisomers

Question 8

What is a monosaccharide?

Answer 8

A simple single sugar unit

Question 9

What is a disaccharide?

Answer 9

2 monosaccharides linked together

Question 10

What is a oligoaaccharide?

Answer 10

3-10 monosaccharides linked in a chain

Question 11

What is a polysaccharide?

Answer 11

Long chains of sugars

Question 12

How is a hemiacetal formed

Answer 12

Aldehyde reacting with an alcohol

Makes a chiral hemiacetal

Question 13

How do you form a pyranose?

Answer 13

A pyranose is a 6 membered ring
Formation of cyclic ring form is simply hemiacetal formation (intermolecular)
The OH reacts with carboxylic acid to make a cyclic acetal

Question 14

What is the c1 position

Answer 14

Anomeric carbon - this is carbon closest to where hemiacetal was formed, next to O

Question 15

How can you tell is a pyranose is beta or alpha?

Answer 15

If it has an axial OH at C1 it is alpha

If it has an equatorial OH at C1 it is beta

Question 16

Describe the configuration of pyranose glucose

Answer 16

All equatorial OH groups and all axial H groups

Question 17

What is a faranose?

Answer 17

5membered ring

Question 18

How can you represent sugars?

Answer 18

Fischer projection- linear and horizontal
Haworth projection- ring 2D
Chair- flying wedge with axial and equatorial

Question 19

What is a glycosidic bonds?

Answer 19

-O-

Question 20

What is mutarotation?

Answer 20

Hemiacetal formation is reversible- you can reopen the ring
Interconversion is called mutatotation
(See mechanism)

Question 21

How can sugars form glycosides?

Answer 21

Hemiacetal + alcohol goes to acetal and water

Question 22

What is the disaccharide of glucose?

Answer 22

Maltose

Question 23

What important disaccharides are there?

Answer 23

Maltose,
Lactose 
(Made from glucose and galactose) 
Sucrose
(Made from glucose and fructose)

Question 24

What is starch?

Answer 24

Polysaccharide in plants- long polymer chain of glucose

Food storage in plants (glycogen in animals)

Question 25

What is cellulose?

Answer 25

This is a structural polysaccharide of glucose

Can form H bonds which are very strong

Question 26

What is the bacterial cell wall made up of?

Answer 26

It is made up of peptidoglycan (overall)
Long polymer of sugars linked to peptides
Made up of glcNAC and Nacetyl nuanic acid