For example, some biological isomers may be more active than others. This means that one isomer can do more work than the next in a metabolic pathway. Isomers are important for life because humans are composed of a number of arrangements of organic molecules such as carbon, hydrogen, oxygen, nitrogen, phosphorus, etc. which require a great level of complexity to carry out essential biological processes. All these arrangements are not only complex in their atom content, but also in their bonds. They are usually composed of a series of single or double bonds that can also form ring structures. For this reason it is more than likely that most organic compounds present in life contain an isomer. Furthermore, it has always been known that the evolution of biological systems favors the use of one isomer over another in order to move forward and benefit that system. Isomerism is also a very important concept to understand in the drug manufacturing process. Every year, numerous drugs are produced that are adapted to combat different disease symptoms throughout the human biological system. Such symptoms include pain, allergies, infections, psychological problems and so on. The way these drugs become effective is through interaction with protein receptors in the human body that will target the specific protein in the problem area. The drug will have to mimic proteins in the problem area, and in most cases the drugs will modify the conformation or function of a protein-enzyme system to regulate that metabolic pathway. The only way a drug can mimic a human protein receptor and change its conformation is through the isomer concept. The drug will have the same type and number of atoms, leading to an identical chemical formula. However, the function will vary, making the drug effective in the metabolic pathway. These examples are enough to demonstrate it