Domain (biology)

The domain is the highest classification category in the now generally accepted systematic classification of living things by Carl R. Woese ( University of Illinois ).

Classification

All living things are divided into three domains in the system, the subdivision is based on the different structure of the ribosomal ribonucleic acid ( rRNA). These three domains are:

  • Bacteria ( Bacteria), dated: Eubacteria The domain of the bacteria is divided into phyla ( strains).
  • The domain Archaea is divided into phyla ( strains).
  • The domain of eukaryotes is divided into kingdoms ( empires ).

For the Eukaryota domain Eukarya also the names and Eucarya are common. Woese, Kandler, and Wheelis used in their published 1990 proposal for the classification of living organisms into three domains, the term Eucarya.

Outside of the system based on the degree of relationship all living things are classified with respect to their cellular structure into two groups:

  • Prokaryotes: organisms without a nucleus
  • Eukaryotes: organisms whose cells have a nucleus

The members of the domains Bacteria and Archaea are prokaryotes, eukaryotes all other living creatures. The classification of all living things in the two groups of prokaryotes and eukaryotes is based on the cell structure and is not a taxonomic classification in the kinship system of living beings. In contrast, the three domains Bacteria, Archaea and Eukaryota taxa in the system of living things, based on the degree of kinship.

Viruses, viroids and prions, which are not generally considered to be living things, are subject to a classification of its own.

Historical systematics

In the earlier system of living beings was no distinction between bacteria and archaea and the archaea were, as they are just like the bacteria prokaryotes, counted among the bacteria. Note: For the modern ( nichttaxonomischen ) eukaryotes and prokaryotes designations were previously called eukaryotes and prokaryotes used, which are very common today. Both spellings are generally considered acceptable.

Swell

  • Carl R. Woese, Otto Kandler, Mark L. Wheelis: Towards a natural system of organisms: proposal for the domains Archaea, Bacteria, and Eucarya. In: Proceedings of the National Academy of Sciences USA. Band 87, 1990, pp. 4576-4579 (PDF).
Phylum
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