Biology 2.2.5: Carbohydrates 3: Polysaccharides As Structual Units

Question 1

structure of cellulose

Answer 1

• is found on plants and made up of beta glucose molecules bonded through a condensation reaction.
• every other beta glucose molecule is coated 180 degrees.

Question 2

what are the chains like in cellulose?

Answer 2

straight and lie side by side

Question 3

why is the beta glucose molecules coated 180 in the formation of cellulose?

Answer 3

the hydrogen and hydroxyl groups are inverted in beta glucose, in order to bond through condensation the molecules must flip every other molecule.

Question 4

what are microfibrils and what is their structure?

Answer 4

when 60-70 cellulose chains are bonded together a microfibril is formed , these bundle together into macrofibrils which contain up to 400 microfibrils, these are embedded in pectins to form plant cell walls

Question 5

what is the structure of plant cell walls?

Answer 5

the microfibrils and macrofibrils have high tensile strength due to the hydrogen and glycosidic bonds
the macrofibrils also run in all directions for extra strength.

Question 6

why is it difficult to digest glucose?

Answer 6

the glycoside bonds between the glucose molecules are less easy to break down

Question 7

why are these features helpful to a plant cell wall?

Answer 7

due to plants not having a rigid skeleton each cell must have the strength to support the whole plant.