Structural Polysaccharides

• The principal structural molecule in plants is cellulose.
  • 50% of all organic carbon in the biosphere is contained in cellulose
  • Forms fibrous parts of plant cell wall, becomes inflexible as time passes.
  • Cellulose is a polymer composed of monomers of glucose like starch and glycogen. The difference is that starch and glycogen are composed entirely of alpha units, while cellulose consists entirely of beta units. This difference bears an effect on the 3d structure, allign parallel forming crystalline cellulose microfibrils. As a result, cellulose is "immune" to enzymes that normally break down storage polysaccharides.
• Chitin is a mayor component in the exoskeletons of antropods, as it is a tough, modified polysaccharide.