- archaea [är kē′ə]pl.n.archaealadj.
* * *▪ bacteriaunicellular organisms that are prokaryotic (that is, do not have a membrane-bound nucleus and other internal units) but that differ in certain physiological and genetic features from bacteria, the most prominent prokaryotes. Archaea have some features in common with bacteria as well as eukaryotes (organisms whose cells contain nuclear membranes), but evidence suggests that archaea are more closely related to eukaryotes than to bacteria.The archaea are aquatic or terrestrial microorganisms that exhibit a diversity of shapes, including spherical, rod-shaped, and spiral forms. Archaea lack murein and ester-linked lipids in the cell walls, which is characteristic of bacteria; instead, they have ether lipids, as well as a number of different cell-wall constituents. Archaea also differ from bacteria in the structure of their ribosomal RNAs, which are used in genetic testing to assess the degree of genetic relatedness among different species. The archaea reproduce using a wide variety of mechanisms, including binary and multiple fission, budding, and fragmentation.Archaea survive in a number of extreme environments, including very hot or saline ones. Archaea may be aerobic, anaerobic, or facultatively anaerobic in their metabolic requirements. Some archaea, such as Halobacterium, require a highly saline environment. Others, such as Methanobacterium, produce methane (CH4) as an end product, while still others are dependent on sulfur for their metabolism. The latter group are among the most thermophilic of the archaea, surviving in temperatures higher than 45 to 50 °C (113 to 122 °F). Still other archaea are found in oceanic thermal vents, growing at temperatures higher than 95 °C (203 °F).
* * *
Look at other dictionaries:
Archaea — Saltar a navegación, búsqueda ? Archaea Rango fósil: Arcaico Holoceno Halobacteria sp. cepa NRC 1, cada … Wikipedia Español
Archaea — Archaea, Archaeen, Überreich der Organismen, dem die ⇒ Archaebacteria zugeordnet werden … Deutsch wörterbuch der biologie
ARCHAEA — Aeolidis in Asia urbs. Pausan. l. 2 … Hofmann J. Lexicon universale
archaea — [är kē′ə] pl.n. ARCHAEBACTERIA archaeal adj … English World dictionary
Archaea — см … Генетика. Энциклопедический словарь
Archaea — Archea redirects here. For the geologic eon, see Archean. For the spider family, see Archaeidae. Archaea Temporal range: Paleoarchean – Recent Halobacteria sp. strain NRC 1, each cell about 5 μm long … Wikipedia
Archaea — Archées … Wikipédia en Français
Archaea — Archaeen Archaeon des Genus Sulfolobus, infiziert mit dem Sulfolobus Virus STSV1. Maßstab = 1 μm. Systematik Klassifikation … Deutsch Wikipedia
archaea — noun plural Etymology: New Latin, from Greek archaios Date: 1990 microorganisms of a domain (Archaea) including especially methane producing forms, some red halophilic forms, and others of harsh hot acidic environments (as a hot spring) compare… … New Collegiate Dictionary
Archaea — A unique group of microorganisms classified as bacteria (Archaeobacteria) but genetically and metabolically different from all other known bacteria. They appear to be living fossils, the survivors of an ancient group of organisms that bridged the … Medical dictionary