starch + cellulose
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12 Terms
starch
storage polysaccharide of plants
where is starch stored
as granules in plastids and amyloplasts
amylose structure
unbranched helix shape
1,4 glycosidic bonds between alpha-glucose molecule
why is amylose helix shaped
more compact so more digestion-resistant
structure of amylopectin
1,4 glycosidic bonds between alpha-glucose molecules
also 1,6 glycosidic bonds between glucose molecules
= branched molecule
why are terminal glucose molecules good
can be easily hydrolysed during cellular respiration/added to for storage
why is starch a storage polysaccharide
compact (store large quants)
insoluble (no osmotic effect, no movement of water)
cellulose structure
polymer with long chains of beta-glucose
joined by 1,4 glycosidic bonds
what is beta-glucose
isomer of alpha-glucose
is rotated 180 to previous molecule, then forms 1,4 glycosidic bond
inverted beta-glucose = hydrogen bonds form in long chains, give cellulose its strength
functions of cellulose
main structural component of cell walls
high tensile strength
cellulose fibres + etc in cell walls = strong matrix
strengthened cell walls = plant support
why is cellulose strong
many hydrogen bonds between parallel chains of microfibrils
