Page 62 - Algae Anatomy, Biochemistry, and Biotechnology

Anatomy 45

FIGURE 2.14 Cells of Biddulphia sp.

Chlorophyceae, and Charophyceae (Chlorophyta). Generally, cell walls are made up of two com-
ponents, a microfibrillar framework embedded in an amorphous mucilaginous material composed
of polysaccharides, lipids, and proteins. Encrusting substances such as silica, calcium carbonate, or
sporopollenin may be also present. In the formation of algal cell walls the materials required are
mainly collected into Golgi vesicles that then pass it through the plasma membrane, where
enzyme complexes are responsible for the synthesis of microfibrils, in a pre-determinate direction.
In the Floridophyceae (Rhodophyta) the cell wall consists of more than 70% of water-soluble
sulfated galactans such as agars and carrageenans, commercially very important in food and
pharmaceutical industry, for their ability to form gels. In the Phaeophyceae (Heterokontophyta)
cell wall mucilagine is primarily composed of alginic acid; the salts of this acid have valuable