C6.2h To be able to recall that DNA is a polymer
made from four different monomers called nucleotides and that other important
naturally-occurring polymers are based on sugars and amino-acids
Naturally occurring polymers based on sugars:
Starch and Cellulose
Polymers
based on sugars: Starch and cellulose
Starch and
cellulose are two naturally occurring polymers that have sugar molecules as
their monomer.
They can be
drawn simply as polymers of glucose units bonded to each other by an ether —O—
linkage.
Cellulose
This is the
cellulose structure:
Starch
Starch is
more complicated because it is composed of two different polymers amylose and
amylopectin.
Amylose has
this structure where the glucose units are linked 1,4 between monomers. As a result amylose curls up into a spiral
structure where as cellulose is a long stranded molecule.
Amylopectin
has a branched structure and this means the entire molecule is more open and
water soluble.
Here is a
table summarising the different naturally occurring polysaccharide polymers:
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