> someone wrote:
> All glucose is the basic unit making up all or part of many
> sugars...and is also the building block of starches and cellulose.
> The main difference between starch and cellulose is the length of
> the chain.
Actually, that is an oversimplification and partly erroneous. The
main difference between starch and cellulose is the type of bond
between the sugar (glucose, galactose, fructose, and any
disacharrides, etc.) monomers. starch polymers can be broken down by
amylase, which is a digestive enzyme added from the mouth while
chewing. There are actually two types of amylase, but I'll stop
there.
The reason we can't derive any energy from wood chips is because we
don't secrete cellulase, the enzyme necessary to break down cellulose
polymers. Cellulose has a different type of molecular bond between
the sugar monomers(dimers), and therefore requires a different
enzyme. Termites have bacteria in their digestive systems that
secrete cellulase, thereby allowing the termite to derive energy from
wood chips. Some fungi also secrete an enzyme that will allow
de-polymerization of cellulose, and it is these fungi that companies
are now using to break down wood chips to manufacture ethanol for
vehicle use.
sorry for the long-winded diatribe... ignore if desired.
Gardner
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