Starch, glycogen and Cellulose



Starch is a polysaccharide

Alpa helical structure makes it good for storage (its compact)

starch is insoluble due to its structure - it is therefore the main plant storage sugar

amylase                                                                                            amylopectin

heical stucture                                                                       highley branced chains

properties= usually stored as intracellular starch grains in organelles called plastids

plasids= include green chloroplasts (in leaves) and colourless amyloplasts (in potaotoes)

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Cellulose is another polysaccharide and its the main part of the plant cell walls it is the most abundant orgain polymer

Unlike starch, cellulose is very strong and prevents cells from bursting when they take in excess water

Cellulose consits of long chains of beta glucose molecules joined by beta 1-4 glycosidic bonds

The glucose chains fron chains from rope - like microfibrils which are layered to form a network  

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specific features of cellulose

B-glucose molecules joined by glycosidic links

Alternate B-glucose molecules are rotated through 180 degrees

The chains can be very long with between 1000-10000 glucose molecules

This results in the cellulose molecule forming very straight long umbranced chains

Hydroxyl (-OH) groups project from both sides of the chain

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Animals store it as glucogen for quick energy resources plants store it as starch

Contains Alpha 1-6 glycosidic bonds that produce an even more branched structure

Glycogen is stored as granules particullary in muscles and the liver

Glycogen is less dence and more soluble than starch and is broken down more rapidly this indicates the higher metabolic requirements of animals compared with plants

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