Biomedical Engineering Reference
In-Depth Information
Figure 1-6. Glucose, a monosaccharide, in both its linear and ring form.
Monosaccharide subunits are linked together with glycosidic bonds to
form long polymers, polysaccharides, which are complex carbohydrates
( Fig. 1-7 ) . These polysaccharides perform two essential functions:
structural and storage. Glycogen and starch store energy in a way that
can be retrieved when the organism needs it. Structural saccharides, such
as cellulose from the plant kingdom and chitin in invertebrate arthropods
and insects, act as a mechanical reinforcement phase in a weak organic
“matrix”. Mono- and poly-saccharides exist in two structural forms:
linear molecules or as a ring. Monosaccharides in ring form have the
ability to polymerize, via a condensation reaction (releasing water), to
give stiff and straight chains of polysaccharides. Figure 1-7 demonstrates
this reaction, which is reversible by hydrolysis (addition of a water
molecule).
Hydrolysis
Figure1-7. Monosaccharides reacting by condensation to form polysaccharides, and by
undergoing hydrolysis polysaccharides return to monosaccharides.
The building block of primary interest in the plant kingdom is
cellulose, which can have thousands of monosaccharide units, arranged
such that the bonding oxygen atoms are staggered ( Fig. 1-8 ) . Because of
 
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