Viruses. Everyone knows about them and has experienced them personally in their bodies multiple times within their lifespan. But what exactly are they and do virus belong on the phylogenetic tree of life or not? The defining characteristics of life according to Biologists are: order, sensitivity or response to the environment, reproduction, adaptation, growth and development, regulation, homeostasis, energy processing, and evolution. Although viruses can attack living organisms, cause diseases, and even reproduce, they do not meet all the criteria that Biologists use to define life. One of the lessons, and a question on a couple exams was why viruses are not considered living. With that question as well as the well-known and recognized list Biologists go by to classify living and non-living organisms and the extensive research from David Moreira and Purificación López-García, I would have to lean more towards the side of viruses not being …show more content…
According to them they only compare in information content and any other comparisons that could happen is because of the host cell; not the virus alone. Once a virus has taken over a cell it can reproduce but only because it is now part of the cell. A virus cannot reproduce on their own. They are essentially, in Moreira and López-García's own words, gene robbers. Viruses such as the Mimivirus, evolve in the protein synthesis via HGT (Horizontal Gene Transfer) implying that viruses never had the capacity to synthesize their own proteins. Another point brought up in this article is, "most viral genes involved in energy and carbon metabolism, transcription, translation and replication with cellular homologues were acquired by viruses through