[en] The process to decipher the genetic code has taken several years and it began with the investigations that he carried out toward half of the XIX century the Czech monk Gregor Mendel who used characteristic contrasting in the plants to study the laws of the inheritance. He made two surprising discoveries. First that many characteristics are inherited in a form of everything or anything: a plant is high or short, and their seeds are flat or rough and second that disappears during a generation when crossing those plants to each other one of the characteristic. When crossing a short plant with a discharge, in the first generation, high plants will only be obtained, but when crossing them again, the characteristic that didn't show during a generation, the short plant will appear again. The article is about the genes and chromosomes, mutations and like the genes work among other topics