Questions about the origin and definition of life can be answered from different perspectives: thermodynamics, physiological, metabolic, biochemical or genetic. The latter focuses on the characterization of information flows and nucleic acids and proteins that carry. Efforts to consolidate these perspectives lead to a definition derived from the so-called cell theory, based on three basic elements: the presence of a semipermeable boundary (cell membrane), a unit of energy production and processing systems and management information (the proteome and the genome). These assumptions define minimum cellular organism as simple as possible. But we shall see, this is just theory. The plasticity of nature and the potential inherent in the evolution have led to bridge the world of living beings who are in a real interface, which meet some of these requirements, but lack other to survive and prosper independently.

One mechanism that has encouraged the emergence of these organisms is endosymbiosis: an example is provided by bacteria that live permanently in specialized tissues of insects and are transmitted from generation to generation. But how genomes have evolved from these organisms over millions of years to build a symbiotic relationship improved? This is one of the research group working in the Cavanilles Institute of Valencia, coordinated by Amparo Latorre and Andrés Moya.