Carbohydrate Chemistry

Question 1

what is the general formula of a carbohydrate

Answer 1

Cx(H20)y

Question 2

what are carbohydrates

Answer 2

polyhydroxy aldehydes or ketones or substances that can be hydrolysed to give polyhydroxy aldehydes or ketones

Question 3

What increases as number of carbons increases

Answer 3

isomers of carboyhdrate

Question 4

what is important if we need to develop specific oligosaccharides to examine its biological properties

Answer 4

important to develop synthetic methods which only allow access to the regio and stereoisomer of choice

Question 5

what are monosaccharides

Answer 5

are defined as monomer units that are not connected to other such units

Question 6

what are disaccharides

Answer 6

formed when two monosaccharides join together

Question 7

what are trisaccharides

Answer 7

when three monosaccharides units join together

Question 8

what is a polysaccharide

Answer 8

structures which contain more than ten monosaccharides joined together by glycosidic bonds

Question 9

what are carbohydrate units joined together by

Answer 9

glycosidic bonds

Question 10

what are the two positions a group can lie

Answer 10

equatorial or axial

Question 11

what are the two faces of chair conformation

Answer 11

alpha (bottom)

beta (beta)

Question 12

Role of Carbohydrates

Answer 12

energy storage

structural compoenents of skeletal components

first point of contact when cells interact

cell recognition and differentiation

Question 13

why are carbohydrates the first point of contact when cells interact

Answer 13

carbohydrates reside on the surface of all cells and are involved in a multitude of biological processess

Question 14

what do cancer cells do

Answer 14

they differ from healthy cells and often temrinate in sialic acid which has a carboxylic acid functional group

Question 15

give 3 examples of tumour associated carbohydrate antigens

Answer 15

Sialyl lewis
T-Antigen
MBr 1 antigen

Question 16

What therapeutic opportunities exist for carbohydrates

Answer 16

vaccination approaches based on antibodies to disease associated carbohydrates

inhibition of the enzymes associated with the synthesis of disease associated carbohydrates

blocking the interactions of the disease asociated carbohydrates with their receptors

developing prodrugs based on disease associated enzymes

Question 17

inhibition of that enzyme is a plausible is a reasonable decision

Answer 17

If a glycosidase or glycosyl transferase enzyme is up-regulated and causes unusual carbohydrates to form

Question 18

when is inhibition of that enzyme used

Answer 18

cancer
aids
diabetes

Question 19

what is a prodrug

Answer 19

a biologically inactive compound which can be metabolized in the body to produce a drug.

Question 20

Theoretically what does oligosaccharides need to be produced

Answer 20

one hydroxyl group of a monosaccharide acceptor with the anomeric center of a further monosaccharide donor to furnish a disaccharide unit.

a further monosaccharide donor to furnish a disaccharide unit.

Question 21

Give example of chemical problems which complicate the process

Answer 21

reactivities of hydroxyl groups - all secondary have similar reactivity so hard to bias which reacts first.

possibility of forming different isomers - due to reactions of different hydroxyl groups

the carbohydrate monomers can exist in a variety of forms and the various forms can interconvert upon exposure to aqueous media

Question 22

what is more thermodynamically stable due to the anomeric effect

Answer 22

alpha anomer

Question 23

what is anomeric effect

Answer 23

thermodynamic preference for polar groups bonded

to C-1 (the anomeric carbon of a glycopyranosyl derivative) to take up an axial position

Question 24

what are carbohydrates made in

Answer 24

biological systems using enzymes

Question 25

what are the advantages of enzymatic synthesis

Answer 25

protecting group strategies are not needed

the reactions occur in aqueous solutions therefor environmentally friendly

allow access to specific regio and stereoisomers

purification is therefore simpler

Question 26

what are the disadvantages of enzymatic synthesis

Answer 26

expensive

enzymes for access to specific linkages have not yet been isolated cloned and made commercially available

small quantities of materials available

enzymes allow access to specific regio and stereoisomers from natural substrates therefore the preparation of wide liberties of compounds for high throughput analysis is not always viable

Question 27

what are reactions of carbohydrates dependent on

Answer 27

functional groups within the molecule as it provides the characteristics

Question 28

what two main properties do reactions of carbohydrates display

Answer 28

polyhydroxy compounds and carbonyl

Question 29

what are the main charactistics of the hydroxyls

Answer 29

deprotection

protection

Question 30

what is a protecting group

Answer 30

A temporary alteration in the nature of a functional group so that it is rendered inert under the conditions in which reaction occurs somewhere else in the molecule.