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Life is divided into domains, which are subdivided into further groups. Intermediate minor rankings are not shown. In biological taxonomy, a domain (/ d ə ˈ m eɪ n / or / d oʊ ˈ m eɪ n /) (Latin: regio [1]), also dominion, [2] superkingdom, realm, or empire, is the highest taxonomic rank of all organisms taken together.
In biology, taxonomic rank (which some authors prefer to call nomenclatural rank [1] because ranking is part of nomenclature rather than taxonomy proper, according to some definitions of these terms) is the relative or absolute level of a group of organisms (a taxon) in a hierarchy that reflects evolutionary relationships.
The three-domain system adds a level of classification (the domains) "above" the kingdoms present in the previously used five- or six-kingdom systems.This classification system recognizes the fundamental divide between the two prokaryotic groups, insofar as Archaea appear to be more closely related to eukaryotes than they are to other prokaryotes – bacteria-like organisms with no cell nucleus.
This six-kingdom model is commonly used in recent US high school biology textbooks, but has received criticism for compromising the current scientific consensus. [13] But the division of prokaryotes into two kingdoms remains in use with the recent seven kingdoms scheme of Thomas Cavalier-Smith, although it primarily differs in that Protista is ...
Systematic biology (hereafter called simply systematics) is the field that (a) provides scientific names for organisms, (b) describes them, (c) preserves collections of them, (d) provides classifications for the organisms, keys for their identification, and data on their distributions, (e) investigates their evolutionary histories, and (f ...
In molecular biology, a protein domain is a region of a protein's polypeptide chain that is self-stabilizing and that folds independently from the rest. Each domain forms a compact folded three-dimensional structure. Many proteins consist of several domains, and a domain may appear in a variety of different proteins.
The two-domain system is a biological classification by which all organisms in the tree of life are classified into two domains, Bacteria and Archaea. [1] [2] [3] ...
Species can be placed in a ranked hierarchy, starting with either domains or kingdoms. Domains are divided into kingdoms . Kingdoms are divided into phyla (singular: phylum ) — for animals ; the term division , used for plants and fungi , is equivalent to the rank of phylum (and the current International Code of Botanical Nomenclature allows ...