Carbohydrates 5: Structural Units

Question 1

Properties of cellulose

Answer 1

Found in cell walls
Tough
Insoluble
Fibrous
Homo polysaccharide
15 000 b glucose

Question 2

Structure of cellulose

Answer 2

Straight chain of b glucose

Question 3

How are the b glucose molecules aligned?

Answer 3

Every other molecule is flipped 180 degrees

Question 4

What stops the chain spiraling

Answer 4

1-4 glycosidic bond and the 180 degree flip and hydrogen bonding

Question 5

How are cellulose macro fibrils formed

Answer 5

The b glucose chains form cellulose chains 60 to 70 of them form micro fibrils and 400 microfibrils bundle to form a macro fibrils which criss crosses and overlaps forming the cellulose structure

Question 6

How is cellulose strengthened

Answer 6

Hydrogen bonds between the cellulose chains

Question 7

Why is cellulose a great material for cell walls?

Answer 7

Micro/macro fibrils have high tensile strength because of hydrogen and glycosidic bonds
Macro fibrils run in all directions (criss cross)
Difficult to digest because the glycosidic bonds are less easy to break.

Question 8

What helps the plant cell wall do its job well?

Answer 8

Each cell needs strength to support the plant(no skeletons)
Space between macro fibrils for water and mineral ions to pass through making the cell wall permeable.
The wall has high tensile strength preventing lysis
Macro fibrils can be reinforced making parts waterproof.

Question 9

What are some example of things which contain cellulose?

Answer 9

Cotton, cellophane, celluloid, paper

Question 10

What are bacterial cell walls made of?

Answer 10

Peptidoglycan made from long polysaccharide chains cross linked by peptide chains(made of amino acid)

Question 11

What are exoskeletons made of?

Answer 11

Chitin which has a acetyl amino group rather than a hydroxyl group on carbon 2
It forms cross links of acetylglucosamine

Question 12

What are macro fibrils imbedded in?

Answer 12

Pectins