bacteria
bacteria (bak-teer-iă) pl. n. (sing. bacterium) a group of microorganisms all of which lack a distinct nuclear membrane and most of which have a cell wall of unique composition. Most bacteria are unicellular; the cells may be spherical (see coccus), rodlike (see bacillus), spiral (see Spirillum), comma-shaped (see Vibrio) or corkscrew-shaped (see 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. Bacteria reproduce asexually by simple division of cells. They live in soil, water, or air or as parasites of humans, animals, and plants. Some parasitic bacteria cause diseases by producing poisons (see endotoxin, exotoxin).
—bacterial adj.
—bacterial adj.
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bacteria
