The Structure of Mono, Di & Polysaccharides

Starch

→ Its a polysaccharide

→ Starch is constructed from 2 different polysaccharides

Eg : Amylose & Amylopectin

→ the monomers of starch is Alpha glucose

→ Starch is formed by condensation

Amylose

→ Amylose is an unbranded chain of glucose molecules

→ join by the 1 & 4 glycosidic bond

→ the glucose is coiled together → compact molecules

→ water soluble

→ 200 unit glucose

→ Helical structure

Amylopectin

→ Polymer of alpha glucose

→ bonded with 1.4 & 1,6 glycosdic bond

→ Branch 25 - 30 glucose molecules

→ not soluble

→ Due to the side branches , these can act upon by many enzymes. Therefore broken down to release energy.

Key properties of Starch

The Structure of starch relate to its functions

→ Amylose form a tight helix due to its compact molecules

→ Can store large amount of glucose

→ Insoluble in water → no osmosis occurs

→ Amylose + Amylopectin =) the glucose molecules are too big → too large to diffuses out of the membrane

The enzyme can break down rapidly → break down the glycosdic bond by the hydrolysis reaction.

→ Find in plant cells

cellulose

→ is a component of the cell wall in plants

→ Long unbranded of beta - glucose

→ monomers of beta glucose

→ Made by condensation

→ unbranded polysaccharide

Key properties of cellulose

→ Microfibrils are strong thread made up of cellulose chains , parallel to another that are joined by hydrogen bond in between.

→ beta branch → beta sheets → cellulose fiber → cellulose cell wall

→ Forming strong linkages

→ cellulose can stop the cell from bursting under osmotic pressure.

→ high tensile strength

→ insoluble

→every 2nd beta flips to that 2 beta glucose can be attached → condensation

Glycogen

→ It’s the main energy stored molecule in animals.

→ Monomer of alpha glucose

→ Joined by 1, 4 glycosdic bond & 1,6 glycosdic bond

→ Also found in liver and muscle cells

→ Insoluble + compact

→ Large surface area / glycogen is broken down faster than starch due to the higher SA / many branch ends

Key properties of glycogen

→ insoluble, it has no effect on H2O potential

-. No osmosis

→ lots of free ends → allowed enzyme can convert glycogen back to glucose rapidly ( Animals )

→ metaboliclity inactive

→ more branched structures than starch, more compact → stored in small space

→ high ratio of respiration

what are the key properties of glucose ?

Soluble + Polar

has chemical energy in its bonds

its a source of energy / respiratory substrate