3 polysaccharides

how are polysaccharides created?

condensation reactions between many glucose monomers

what 3 examples are created from glucose monomers?

• starch

• glycogen

• cellulose

what monomers are starch created from?

two polymers of alpha glucose (amylose and amylopectin)

where is starch found in?

starch grains inside plant cells (e.g. chloroplast)

what’s the function of starch?

insoluble fat store of glucose

how is amylose created?

by a condensation reaction and forms a 1-4 glycosidic bond which coils to form a helix

how is amylopectin created?

formed by a condensation reaction

what monomer is cellulose created by?

a beta glucose

where’s cellulose found in?

cell wall of plants

what’s the function of cellulose?

provides structural strength to cell wall

what’s glycogen created from?

alpha glucose

where’s glycogen found?

muscle and liver cells on animals

what’s the function of glycogen?

and insoluble store of glucose

what’s the structure of starch?

made of 2 polymers

• amylose - an unbranched helix

• amylopectin - branched molecule

what’s the structure of cellulose?

polymer forms long, straight chains which are held in parallel by many hydrogen bonds to form fibrils

what’s the structure of glycogen?

a highly branched molecule

how does starch’s structure lead to its function?

• helix can compact a lot of glucose in a small space

• branched structure increases surface area for rapid hydrolysis back to glucose

• insoluble - won’t affect water potential

how does cellulose’s structure lead to its function?

• many hydrogen bonds provide collective strength

• insoluble - won’t affect water potential

how does glycogen’s structure lead to its function?

• branched structure increases surface area for rapid hydrolysis back to glucose

• insoluble - won’t affect water potential

what’s the test for starch?

• add iodine solution

• positive result = orange —> blue/black

what’s the test for reducing sugars?

• add benedict’s solution and heat

• positive result = blue —> green, yellow, orange, brick red (more red = higher concentration of reducing sugar)

what’s the test for non reducing sugars?

• following a negative benedict’s test where the solution remains blue

• add acid and boil

• cool solution then add alkali to neutralise

• add benedict’s solution and heat

• positive result = blue —> orange or brick red (more red = higher concentration of reducing sugar)