Polysaccharides

Question 1

What 5 traits create diversity in polysaccharides?

Answer 1

Branching
Chain length 
Monosaccharide composition 
Glycosidic bond positions 
Anomeric carbon positions

Question 2

What controls polysaccharide folding?

Answer 2

Steric constraints and H bonds

Question 3

What are 3 functions of pollysaccharides?

Answer 3

Energy storage
Structural support
Ground substances - gels

Question 4

What are the 3 energy storage polysaccharides found in nature?

Answer 4

Starch, glycogen, and glucans/dextrans

Question 5

What are the 4 structural polysaccharides?

Answer 5

Cellulose, chitin, peptidoglycan, agar

Question 6

What is starch?

Answer 6

The energy storage polysaccharide found in plants

Question 7

What are the two types of starch?

Answer 7

Amylose and amylopectin

Question 8

What is the structure of amylopectin?

Answer 8

Helical with a few branches and long chains. The chain monosaccharides are linked by alpha1-4 glycosidic bonds and the branches are alpha1-6

Question 9

What is the structure of amylose?

Answer 9

Helical and linear and long chains. Glycosidic bonds are alpha1-4

Question 10

Where are the reducing ends in starch?

Answer 10

All on one side

Question 11

Why is branched starch a good thing?

Answer 11

Allows for efficient packing into granules and high density of stored glucose

Question 12

What is glycogen?

Answer 12

Glucose storage polysaccharide in animals, fungi, and bacteria

Question 13

What is the structure of glycogen?

Answer 13

Highly branched polymer. Chains have alpha1-4 linkages and branch points have alpha1-6 linkages

Question 14

Why is it advantageous to store glucose as glycogen?

Answer 14

More compact and doesn’t increase the solute concentration of glucose in the cell, so no osmotic stress

Question 15

Why is the branching of glycogen advantageous?

Answer 15

Many ends are available so lots of glucose can be liberated rapidly

Question 16

What are 2 extracellular polysaccharides produced by bacteria?

Answer 16

Dextran and mutan

Question 17

What is the structure of dextran?

Answer 17

A glucose polymer with alpha1-6 linkages

Question 18

What is the structure of mutan?

Answer 18

Glucose polymer with alpha1-3 linkages that is branched. Is sticky and can withstand acid

Question 19

What is cellulose?

Answer 19

Unbranched glucose polymer that is a major structural component of plant cell walls. Packs into sheets and H bonds between the chains

Question 20

What type of linkage links glucose together in cellulose?

Answer 20

Beta1-4

Question 21

What is the structure of chitin?

Answer 21

Linear chains of beta1-4 N-acetylglucosamine

Question 22

What is peptidoglycan?

Answer 22

A heteropolysaccharide that makes up bacterial cell walls and protects the cell from osmotic stress

Question 23

What is the structure of peptidoglycan?

Answer 23

One N-acetylglucosamine (NAG) linked to an N-acetylmuramic (NAM) acid with a beta1-4 bond and cross linked by peptides

Question 24

What enzyme cleaves peptidoglycan?

Answer 24

Lysozyme

Question 25

What is agar?

Answer 25

A gelling polysaccharide which makes up the cell wall of marine algae

Question 26

What are the two types of agar?

Answer 26

Agarose and agaropectin

Question 27

What is the structure of agarose?

Answer 27

Long linear chain with beta1-4 linkages. The sugars are modified with an ether and a sulfite

Question 28

What is the structure of agaropectin?

Answer 28

Shorter, branched chains with beta1-4 linkages

Question 29

Is agarose or agaropectin better for making gels?

Answer 29

Agarose

Question 30

Is agarose or amylopectin better for making agar plates?

Answer 30

Agaropectin

Question 31

What are glycosaminoglycans?

Answer 31

Really important components of the extracellular matrix, as it makes up the gel and fills up a lot of space

Question 32

What is the general structure of a glycosaminoglycan?

Answer 32

Long chains of repeating disaccharide units - Hexosamine + uronic acid. Many are sulfated and have strong negative charges and extended helical chains

Question 33

What are the 2 monosaccharides that make up hyaluronate? How long is the chain? How charged is it?

Answer 33

GluA + GlcNAc. Huge chains, over 50 000 units. Least negatively charged out of all GAGs

Question 34

What does heparin do?

Answer 34

Prevents coagulation, is the most negatively charged out of all GAGs. Is polar and binds to water to make a gel

Question 35

Why are glycosaminoglycans in the extracellular matrix?

Answer 35

Fill up space really well and are metabolically cheap

Question 36

How are glycosaminoglycans usually found?

Answer 36

Usually as glycoconjugates. Only hyaluronate is found free