= Bacteria
{wiki}
<Bacteria> are a major evolutionary lineage of <organisms> with <prokaryotic> cellular organization. <Escherichia coli> and <cyanobacteria> illustrate its variety: the same broad cellular plan supports different kinds of <metabolism>. Most <bacteria> have a <cell wall> containing <peptidoglycan>; <archaea> do not have <peptidoglycan> walls. A <cell wall> and a <cell membrane> are distinct structures, and some <bacteria> lack a <cell wall>. See https://openstax.org/books/biology-2e/pages/22-2-structure-of-prokaryotes-bacteria-and-archaea[OpenStax Biology 2e, 22.2: bacterial envelopes].
The usefulness of recognizing <bacteria> extends beyond naming: it identifies a shared evolutionary background for comparing <genes>, <proteins> and cellular mechanisms. A familiar shape or the absence of a <cell nucleus> alone cannot distinguish <bacteria> from <archaea>; molecular comparisons, including <ribosomal RNA>, supply additional evidence.
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