Non-cellular life is life that exists without cells. This term usually is applied to earth-based life, and presumes the phylogenetic classification of viruses as lifeforms. Cells in culture, stained for keratin (red) and DNA (green). ... A phylogeny (or phylogenesis) is the origin and evolution of a set of organisms, usually of a species. ... Classification may refer to: Taxonomic classification See also class (philosophy) Statistical classification Security classification Hint: Language use may refer to a taxonomic classification that is used for statistical purposes also as a statistical classification (like International Statistical Classification of Diseases and Related Health Problems). ... Groups I: dsDNA viruses II: ssDNA viruses III: dsRNA viruses IV: (+)ssRNA viruses V: (-)ssRNA viruses VI: ssRNA-RT viruses VII: dsDNA-RT viruses A virus (Latin, poison) is a microscopic particle that can infect the cells of a biological organism. ...

In discussing the taxonomic domains of life, the terms Acytota or Aphanobionta are occasionally used as the name of a viral kingdom, domain, or empire. The corresponding cellular life name would be Cytota. Non-cellular organisms and cellular life would be the only two subdivisions of earthly life -- also known as terrestrial organisms, Biota, Naturae, or Vitae. Taxonomy (from Greek ταξινομία from the words taxis = order and nomos = law) may refer to either a hierarchical classification of things, or the principles underlying the classification. ... In biology, a domain (also superregnum, superkingdom, or empire) is the top-level grouping of organisms in scientific classification, higher than a kingdom. ... Ernst Haeckels presentation of a three-kingdom system (Plantae, Protista, Animalia) in his 1866 Generelle Morphologie der Organismen. ... In biology, a domain or empire is the top-level grouping of organisms in scientific classification. ... Cellular life is life with cells. ... Galunggung in 1982, showing a combination of natural events. ...

The issue of life without cellular structure came to the fore with the 2003 discovery that the large and complex Mimivirus can make its own proteins. This recent discovery increased the number of proponents of a fourth -- that is, viral -- domain of life among virologists and bacteriologists. However, the content of this proposed domain is much debated as to whether it should include all viruses, most viruses, or just nucleocytoplasmic large-DNA microbes such as the Mimivirus. The mimivirus is a giant double-stranded DNA virus with mature particles of 400 nm in diameter (icosahedral capsid). ... A representation of the 3D structure of myoglobin, showing coloured alpha helices. ... Virology is the study of viruses and their properties. ... Microbiology (in Greek micron = small and biologia = studying life) is the study of microorganisms, including unicellular (single-celled) eukaryotes and prokaryotes, fungi, and viruses. ... The general structure of a section of DNA Deoxyribonucleic acid (DNA) is a nucleic acid that contains the genetic instructions for the biological development of a cellular form of life or a virus. ... A microorganism or microbe is an organism that is so small that it is microscopic (invisible to the naked eye). ...

See also

• Alternative biochemistry