Biopolymers are natural polymers produced by living organisms; in other words, they are polymeric biomolecules derived from cellular or extracellular matter. Biopolymers contain monomeric units that are covalently bonded to form larger structures. Lots of biopolymers can be used for regenerative medicine, tissue engineering, drug delivery, and overall medical applications due to their mechanical properties. They provide characteristics like wound healing, and catalysis of bio-activity, and non-toxicity. There are three main classes of biopolymers, classified according to the monomeric units used and the structure of the biopolymer formed: polynucleotides (RNA and DNA), which are long polymers composed of 13 or more nucleotide monomers; polypeptides, which are short polymers of amino acids; and polysaccharides. Biopolymers can be polynucleotides (such as the nucleic acids DNA and RNA), polypeptides (that is, proteins) or polysaccharides (that is, polymeric carbohydrates). These consist of long chains made of repeating, covalently bonded units, such as nucleotides, amino acids or monosaccharides.