Page 48 - Biology_F5

Cytology

give cellulose its considerable stability to also used in the manufacturing of fabrics.
make it a valuable structural material. It is Rayon, a product of cellulose extract
the major component of the plant cell walls, is used in manufacturing of industrial
where it plays structural role. belts, tyre cods and clothing. Cellulose
derivatives have various uses, for
Cellulose’s structural strength has made it example; cellophane is used in packaging,
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a valuable raw material in manufacturing and celluloid is used in manufacturing
various industrial products, such as cotton, of photographic film. Other cellulose
which is a pure form of cellulose. It is products include paper and explosives.

Figure 1.26: Structure of cellulose
Figure 1.27 Structure of cellulose
Chitin cellulose, has its repeating units joined in
Chitin is an extracellular structural β (1,4) linkages. However, the two differ in
polysaccharide found in large quantities that, the hydroxyl group (-OH) of chitin at
in exoskeletons of arthropoda. Chitin is also carbon atom number two (C-2) is replaced by

found in small amounts in sponges, molluscs, –NH.CO.CH (acetyl-amino) group. It is
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annelids and cell walls of fungi. Also, it has thus a result of an amino sugar, glucosamine,
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been identified in the cell walls of some combining with an acetyl group (CH CO ).
green algae. Its structure and chemistry are Chitin, is therefore a polymer of acetyl,
similar to those of cellulose. Chitin, like glucose and amine (Figure 1.27).

Form Five Student’s Book 41
Figure 1.28 Structure of chitin