glycobiology - lecture 1

Question 1

What are the 3 mains classes of carbohydrate polymers?

Answer 1

Monosaccharides
Oligosaccharides
Polysaccharides

Question 2

How are disaccharide attached?

Answer 2

O-glycosidic bonds

Question 3

What is the full name of maltose?

Answer 3

Alpha - D glucopyranosy - 1-4 , D - glucopyranose

Question 4

What are other important Disaccharides?

Answer 4

• Lactose – ß-galactosyl-(14)-glucose

- Sucrose – α-glucosyl-(12)-fructose

Question 5

What are oligosaccharides?

Answer 5

2 – 8 linked monosaccharides

Most implants

Question 6

How can polysaccharides be divided into groups?

Answer 6

• structural

- storage

Question 7

What are the main examples of structural polysaccharides?

Answer 7

• cellulose

- Chitin

Question 8

Structure of cellulose

Answer 8

homopolymer of glucose units which are β(14) linked, unbranched

Question 9

Structure of chitin

Answer 9

homopolymer of N-acetylglucosamine β(14) linked, unbranched

Question 10

What shape do Beta 1-4 links form?

Answer 10

form straight chains

Question 11

What are the main examples of polysaccharide storage molecules?

Answer 11

• starch

- glycogen

Question 12

How is starch made up?

Answer 12

α-amylose – unbranched glucose polymer linked by α(14)

amylopectin - α(16) linked branches every 24-30 glucose

Question 13

What is the structure of glycogen?

Answer 13

Very similar to amylopectin but even more branched

Question 14

What linkages cause could structures

Answer 14

alpha 1 - 4

Question 15

What are Glycosaminoglycans (mucopolysaccharides)?

Answer 15

A range of polymers composed of repeating disaccharide units
Typically several 100s of units long
The major components of ground substance

Question 16

What is an example of a Glycosaminoglycans (mucopolysaccharides)?

Answer 16

Hyaluronic acid (in ground substance, synovial fluid and vitreous humour of the eye)

Question 17

What is the real name of hyaluronic acid?

Answer 17

Disaccharide of D-glucuronic acid β(13) linked to N-acetyl-D-glucosamine

Question 18

Hyaluronic acid

Answer 18

250 to 25 000 disaccharide units
Forms a rigid and highly hydrated structure
Viscous solution, absorbs shocks and shearing forces

Question 19

How can carbohydrates attach to proteins

Answer 19

N-linked

O-linked

Question 20

How are carbohydrates O linked?

Answer 20

attachment is to the OH group of either Ser or Thr

Question 21

How are carbohydrates N linked?

Answer 21

N-linked – N-acetylglucosamine (NAG) β linked to the amide nitrogen of Asn in the protein sequence Asn-X-Ser or Asn-X-Thrwhere X is any amino acid except Pro