Archaea

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Archaea

Evolutionary biology
One of the three domains of living organisms: Archaea, Bacteria and Eukaryota. While Archaea are single-celled, they are unlike bacteria given their independent evolutionary history. Archaea differ from Eukaryota in their ribosomal structure and the presence—in some—of introns in the genome, as well as other features (e.g., different membrane composition).
 
Molecular biology
Archaea are of interest in biotechnology as they have unique biochemical features (e.g., enzymes of theromophiles, such as Taq polymerase, the “workhorse” enzyme of PCR) and are extremely stable at high temperatures. Archaea include metabolic oddities (e.g., extreme halophiles, which live in extremely salty environments), methanogens (which produce methane) and sulphur-dependant extreme thermophiles (which can live in extremely hot environments).

Archaea phyla
• Crenarchaeota
• Euryarchaeota
• Korarchaeota
• Nanoarchaeota
• Thaumarchaeota (recently proposed)
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Archaea

( formerly
Collins Dictionary of Biology, 3rd ed. © W. G. Hale, V. A. Saunders, J. P. Margham 2005
References in periodicals archive ?
Banks et al., "Fluid chemistry and evolution of hydrothermal fluids in an Archaean transcrustal fault zone network: The case of the Cadillac Tectonic Zone, Abitibi greenstone belt, Canada," Canadian Journal of Earth Sciences, vol.
The second column represents a lake of the Archaean Eon (3500 million years ago) and holds an anaerobic community predominated by purple sulfur phototrophic bacteria (Chromatium sp., Thiocapsa sp.) and green sulfur bacteria (Chlorobium sp.).
1993) differs from the cotectic basaltic magmas inferred to be parental to Archaean megacrystic, layered intrusive, ocean basin, and lunar anorthosite.
Kilimapesa Gold's Lolgorien gold project is located in southwestern Kenya within the historically producing Migori Archaean Greenstone Belt.
Watkins worked on the surveys with King in the mid-1860s, producing images that would come to stand for the "archaean America" King elaborated in prose.
For example, preeminent evolutionary biologist Ernst Mayr, who died in 2005, never accepted an archaean domain.
"When I get tired of the modern world, I imagine the Archaean world when stromatolites were the only signs of life," he remarks.
The investigated area has granites of Archaean age and is unconformably over lained by the Deccan traps with intertrappean beds.
129) that "It will be a long time before such developments can be applied to the whole of the Proterozoic, or to the Archaean, and the present chapter should, therefore, be regarded as an interim report on a challenging topic." The chronometric subdivision of the Precambrian, ratified by IUGS in 1990, thus involves the familiar break down into the Archean and Proterozoic eons, further subdivided respectively into Eo-, Paleo-, Meso and Neoarchean eras, and Paleo-, Meso-, and Neoproterozoic eras.
In fact the almost anaerobic blastula stage embryo could reflect the existence of multicellular organisms in the Archaean anoxic world.
In fact, the blastula-stage embryo could reflect the existence of multicellular organisms in the archaean anoxic world.