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Which three domains are recognized in Carl Woese’s classification system?
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A herd of African elephants (Loxodonta africana) drinking from the Chobe River, Botswana.
In Carl Woese’s classification system, all life is organized into three distinct domains based on molecular characteristics, particularly ribosomal RNA sequences. These three domains are:12
- Bacteria: Comprising the traditional or true bacteria (formerly known as eubacteria).12
- Archaea: Consisting of prokaryotic organisms that are biochemically and genetically distinct from true bacteria.31
- Eukarya: Including all eukaryotes, such as animals, plants, and fungi.12
This system replaced earlier models that primarily divided life into prokaryotes and eukaryotes, recognizing that archaea represent a separate evolutionary lineage.31