= Eukaryote
{wiki}
= Eukaryotic
{synonym}
A <eukaryote> is an <organism> belonging to the lineage characterized by a membrane-bounded <cell nucleus> and extensive cellular compartmentalization. A <nuclear envelope> surrounds the nuclear <genome>; nuclear <chromosomes> are typically linear. <Ribosomes> perform <biological translation> outside the <cell nucleus>. See https://openstax.org/books/microbiology/pages/3-4-unique-characteristics-of-eukaryotic-cells[OpenStax Microbiology, 3.4: nuclear organization and protein synthesis]. Specialized <biological cells> can lose their <cell nucleus>, as mature mammalian <red blood cells> do, while remaining parts of <eukaryotic> <organisms>; see https://openstax.org/books/biology-2e/pages/40-2-components-of-the-blood[OpenStax Biology 2e, 40.2: mature red blood cells].
<Yeasts>, <plants> and <animals> are all <eukaryotes>. Typical cells in these groups have <mitochondria>, but <chloroplasts> belong to photosynthetic <plant> and <algae> lineages, not to every <eukaryote>. A <cell wall> occurs in typical <plant> and <fungus> cells but is absent from <animal> cells. These are comparisons of representative cells, not a checklist every specialized cell must satisfy. See https://openstax.org/books/biology-2e/pages/4-3-eukaryotic-cells[OpenStax Biology 2e, 4.3: nucleus, organelles and representative cells].
The interesting feature is controlled separation: <cell membranes> and <organelle> membranes let different cellular processes occupy distinct compartments while <membrane transport> connects them. The <evolution> of <eukaryotes> also involved partnership: <mitochondria> descend from a bacterial <endosymbiosis>. Modern <phylogenetics> supports an archaeal ancestry for the nuclear lineage, alongside this bacterial contribution; see <two-domain system>. Thus the history of a whole <eukaryote> cannot be read as the history of just one of its <genes>.
\Image[/cell-lineages-and-shared-machinery.png]
{title=Shared cellular machinery and distinguishing organization across <bacteria>, <archaea> and <eukaryotes>}
{description=Original comparison table, not a <phylogenetic tree>. The shared functions do not require identical <molecules>. Entries describe representative cellular organization and explicitly qualify exceptions; column positions imply neither ancestry nor evolutionary rank.}
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