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STARCH
 Polymer of  glucose molecules
 Energy store in plants
 Insoluble
 Can be seen as grains in the chloroplasts with light microscope
 Does not interfere with metabolic reactions or affect water
potential
 Mixture of amylose and amylopectin
Amylose is a straight chain of
glucose molecules. In fact the
chain is floppy, and it tends to coil
up into a helix.
Amylopectin is a chain with about
4% branches. This gives it a more
open molecular structure than
amylose. Because it has more
ends, it can be broken more
quickly than amylose by amylase
enzymes.
Both amylose and amylopectin are broken down by the enzyme
amylase into maltose, though at different rates.
GLYCOGEN
 Polymer of  glucose molecules
 Energy store in animals
 Insoluble
 Can be seen as grains in the liver cells with electron microscope
 Does not interfere with metabolic reactions or affect water
potential
 Because it is so highly branched, it can be mobilised (broken down
to glucose for energy) very quickly.
 Glycogen is similar in structure to
amylopectin. It is a glucose chain
with 9% branches.
CELLULOSE
 Long chains of  glucose molecules
 Structural material of cell walls – strength protects and supports
plant cells
 Long, straight cellulose molecules group together to form
microfibrils
  links are stronger than  links.
 Cannot be digested by amylase – instead digested by cellulase, an
enzyme only found in bacteria.
O
O
O
O
O
O
HO
O
O
OH
O
hydrogen bond
O
O
O
O
HO
O
O
OH
O
O
O
O
HO
O
O
O
O
O
O
O
O
OH