Contents In elaborating on any biological phenomenon and trying to explain the intimate nature of the processes that determine a property or function of living beings, we inevitably in the field of molecular biology. Take for example the study of genes. The classical laws of Mendel are explained immediately in morphological and functional knowledge of the chromosomes. But when we want to know the composition and modus operandi of a gene need to penetrate deep into the double helix structure of DNA by Watson and Crick, the arrangement of purine and pirimid micas, ie the genetic information.By qualifying the possibility of synthesizing an enzyme by a gene, we must continue the process of transmission of the genetic information from nuclear DNA to messenger RNA, the activation of amino acids by RNA carrier, the management of these activated amino acids on the ribosome according to the predetermined pattern by messenger RNA, obtaining the primary structure of the enzyme protein. All these topics are studied in molecular biology But there’s more, the protein, once synthesized, must be ordered in space according to certain rules that are specific spatial conformation (secondary and tertiary structures) and sometimes several molecules associated with the same or different to constitute what is called quaternary structures and quinaria, so that the biological properties of the molecule as an enzyme linked to this complex spatial organization.The well organized protein molecule may prove an enzyme in its catalytic activity, is susceptible to activation or inhibition by certain substances, these actions of transcendental importance for the life of the cell. Similarly, molecular biology is concerned with the chemical structure of the component substances of biological membranes and management of the enzymes that chained actions, P. ej., within the mitochondria, nucleus and other subcellular corpuscles, to explain the mechanical and biochemical cycles determined by the cellular topochemical. The processes of reproduction of viruses, bacteria and higher organisms contain many unknowns about going to solve molecular biology.The mutations produced by physical agents (X rays, gamma rays, heat, etc..) Or chemical (mutagenic substances) have a much more satisfactory explanation the better you know the molecular basis of processes of change in the structure and management of databases DNA nitrogen. The relationship between different species of living things can be established through individual study compared macromolecular substances (proteins) produced by them. Thus, the sequence of amino acids in hemoglobin, myoglobin, cytochromes, pituitary hormones or insulin induces the degree of phylogenetic proximity, by showing the evolution of the protein for progressive changes. Multitude of genetic events such as natural selection, adaptation to environment, species differentiation, and so on., Have their ultimate explanation at the molecular level.Finally, the molecular biology of organisms is providing interesting data for the search for new antibiotics and anti-metabolites, which allow to efficiently and selectively attack the pathogens. But this is not to say that molecular biology is a complete science and perfectly crafted. On the contrary, new discoveries, solving a mystery posing many more questions that are the subject of future research. Today this young science is growing explosively. Moreover, the last and definitive explanation of the behavior of the molecules of living things need to be known in depth, dealing with other branches of science such as sub-molecular biophysics (orbital bonding forces, hybridization, etc.. ) and even sub-atomic physics, which is required for a wealth of knowledge that can never be the property of individual researchers, but scientifically work teams heterogeneous but harmonic combination.