ABSTRACT
Carbohydrates are a major class of compounds composed of free sugars (monosaccharides) or of sugars in polymeric association (polysaccharides). Their essential roles in the metabolism of the protist cell include the following:
The backbone of DNA and RNA.
Intermediary compounds, especially sugar phosphates used in the energy transfer process; this process includes both the release of energy and the harnessing of energy by aerobic (algal and blue-green algal) and anaerobic (bacterial) photosynthesis.
Energy storage reserves: amylopectins, glycogen, laminaran.
Cell wall components: bacterial mureins, fungal and algal cellulose, and fungal chitins.
Extracellular polysaccharides: bacterial cellulose, yeast mannans, fungal glucans.
