Glucosamine is an amino acid (or sugar). It is a predominant particle that is used in the break down of lipids and proteins within the body. This is found within many multi-cellular organisms, and one of its components creates the exoskeletons of crustaceans and arthropods. The main chemical component of glucosamine also forms many cell walls in various types of plants and fungi as well. The exact chemical structure of glucosamine is (C6H13NO5).