bacteria

bacteria
pl. n.; sing. bacterium
a group of microorganisms all of which lack a distinct nuclear membrane (and hence are considered more primitive than animal and plant cells) and most of which have a cell wall of unique composition (many antibiotics act by destroying the bacterial cell wall). Most bacteria are unicellular; the cells may be spherical (coccus), rod-shaped (bacillus), spiral (Spirillum), comma-shaped (Vibrio) or corkscrew-shaped (spirochaete). Generally, they range in size between 0.5 and 5 μm. Motile species bear one or more fine hairs (flagella) arising from their surface. Many possess an outer slimy capsule, and some have the ability to produce an encysted or resting form (endospore). Bacteria reproduce asexually by simple division of cells; incomplete separation of daughter cells leads to the formation of colonies consisting of different numbers and arrangements of cells. Some colonies are filamentous in shape, resembling those of fungi. Transfer of DNA from one bacterium to another takes place in the process of conjugation.
Bacteria are very widely distributed. Some live in soil, water, or air; others are parasites of humans, animals, and plants. Many parasitic bacteria do not harm their hosts; some cause diseases by producing poisons (see endotoxin, exotoxin).

The new mediacal dictionary. 2014.

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  • bacteria — f. microb. Organismo unicelular y procariota perteneciente al reino monera. Su aspecto externo es variado: puede poseer una forma esférica (coco), alargado (bacilo) o helicoidal y aunque se pueden encontrar aisladas, cuando las condiciones son… …   Diccionario médico

  • bacteria — [bak tir′ē ə] pl.n. sing. bacterium [bak tir′ēəm] or bacteria [ModL, pl. of bacterium < Gr baktērion, dim. of baktron, a staff: see BACILLUS] any of a division (Bacteria) of monerans, microorganisms which are typically one celled, have no… …   English World dictionary

  • Bacteria — Bac*te ri*a, n. pl. See {Bacterium}. [1913 Webster] …   The Collaborative International Dictionary of English

  • Bacterĭa — Bacterĭa, Gattung der Gespensterheuschrecken …   Pierer's Universal-Lexikon

  • bacteria — 1847, plural of Mod.L. bacterium, from Gk. bakterion small staff, dim. of baktron stick, rod, from PIE *bak staff used for support. So called because the first ones observed were rod shaped. Introduced as a scientific word 1838 by German… …   Etymology dictionary

  • bactéria — s. f. Nome geral dado aos micróbios unicelulares de forma alongada (bacilos), esférica (cocos) ou espiralada, sem membrana nuclear e que se alimentam segundo o modo vegetal …   Dicionário da Língua Portuguesa

  • bacteria —  Bacteria  Бактерии   Одноклеточные безъядерные живые организмы, обычно диаметром около одного микрона. Бактерии являются одними из самых древних, мельчайших и наиболее простых типов клеток. К настоящему времени описано около десяти тысяч видов… …   Толковый англо-русский словарь по нанотехнологии. - М.

  • bacteria — [n] microorganisms bacilli, germs, microbes, organisms, pathogens; concepts 306,393 …   New thesaurus

  • bacteria — sustantivo femenino 1. Microorganismo formado por una sola célula sin núcleo, que puede causar enfermedades como el cólera, o que interviene en procesos químicos como la fermentación: Hay bacterias buenas y malas para el hombre …   Diccionario Salamanca de la Lengua Española

  • bacteria — (Del gr. βακτηρία, bastón). f. Biol. Microorganismo unicelular procarionte, cuyas diversas especies causan las fermentaciones, enfermedades o putrefacción en los seres vivos o en las materias orgánicas …   Diccionario de la lengua española

  • bacteria — bacterial, adj. bacterially, adv. /bak tear ee euh/, n.pl., sing. bacterium / tear ee euhm/. ubiquitous one celled organisms, spherical, spiral, or rod shaped and appearing singly or in chains, comprising the Schizomycota, a phylum of the kingdom …   Universalium

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