ABSTRACT
All living systems and their biomolecules follow the Laws of Thermodynamics. Polysaccharides are long chains of repeating sugar subunits. While many different sugars can be used as subunits in the polymeric structure, the polysaccharides based on the 6-carbon glucose molecule are by far the most important in the biological world. Glucose is called blood sugar, and it is the major energy molecule in most animals. Cellulose is the major structural molecule of all plant cell walls, from algae to trees. Extracellular enzymes are excreted outside the cell to break down large molecules and allow their passage through the cell wall. The porphyrin ring is used in another important molecule, the chlorophyll molecule which is the basis for photosynthesis. Nitrogen in the form of ammonia or ammonium is a major component not only of proteins but also nucleic acids and many other molecules of life.
