POLYSACCHARIDES: starch + glycogen + cellulose

bonds in amylose

1,4 glycosidic bond

bonds in amylopectin

1,4 and 1,6 glycosidic bonds

bonds in glycogen

1,4 and 1,6 glycosidic bonds

bonds in cellulose

1,4 glycosidic bonds

what is this?

amylose

what is this?

amylopectin

what is this?

glycogen

what is this?

cellulose

amylose: what glucose is it made of?

alpha

amylopectin: what glucose is it made of?

alpha

glycogen: what glucose is it made of?

alpha

cellulose: what glucose is it made of?

beta

structure/shape of amylose

• long chain of glucose twisted to form a helix

• coiled → compact

structure/shape of amylopectin

• branched

• formed by 1,6 glycosidic bonds between 2 glucose molecules

structure/shape of glycogen

• more branched than amylopectin

• more 1,6 glycosidic branching points

structure/shape of cellulose

• straight chain

• orientation of glucose units are flipped which causes a straight chain to be formed

solubility of amylose

less soluble

solubility of amylopectin

insoluble

solubility of glycogen

insoluble

solubility of cellulose

insoluble

how is amylose structure stabilised?

by hydrogen bonds between -O (in OH group) and -H groups on adjacent alpha glucose monomers

functions of amylose

used for energy in plants

as amylose is insoluble, why is this useful?

doesn’t exert any osmotic effect in cells

as amylopectin is branched, why is this useful?

• molecules can be built up by condensation

  • can be broken down by hydrolysis more quickly - due to free ends

function of amylopectin

insoluble so built for storage

is glycogen or amylopectin more branched?

glycogen

if glycogen is more branched, why is this useful?

• more compact

• less space needed for it to be stored

function of glycogen

• storage polysaccharide in animals

• primarily stored in liver/skeletal muscle cells

why are cellulose used to make cell walls?

• insoluble

• enormous tensile strength

• rigid

can cellulose form hydrogen bonds?

yes

function of cellulose (apart from cell wall)

• they form between parallel stands creating structures called microfibrils.

• microfibrils join together to form macrofibrils which join to form fibres.