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Topic: Archaea


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  Types of Microbes: Archaea
There are three main types of archaea: the crenarchaeota (kren-are-key-oh-ta), which are characterized by their ability to tolerate extremes in temperature and acidity.
Although many archaea have tough outer cell walls, these walls contain different kinds of amino acids and sugars than those found in bacteria.
The archaea very much resemble bacteria, so much so that they were once thought to be a weird group of bacteria.
www.microbeworld.org /microbes/archaea/default.aspx   (634 words)

  
  Archaea
The archaea have a curious mix of traits characteristic of
have suggested that the archaea may be the little-changed descendants of the first forms of life on earth.
Archaea may also be enlisted to aid in cleaning up contaminated sites, e.g., petroleum spills.
users.rcn.com /jkimball.ma.ultranet/BiologyPages/A/Archaea.html   (600 words)

  
  Archaea - Wikipedia, the free encyclopedia
Archaea were identified in 1977 by Carl Woese and George Fox based on their separation from other prokaryotes on 16S rRNA phylogenetic trees.
Archaea are similar to other prokaryotes in most aspects of cell structure and metabolism.
In some archaea, the C-40 isoprenoid side-chain is actually long enough to span the membrane, forming a monolayer for a cell membrane with glycerol phosphate moieties on both ends.
en.wikipedia.org /wiki/Archaea   (1621 words)

  
 Archaea Info - Encyclopedia WikiWhat.com   (Site not responding. Last check: 2007-11-07)
The Archaea are one of the three major groups of living organisms, together with the bacteria and eukaryotes.
The Archaea may be treated as a single kingdom or as a domain, in which case the subgroups may be ranked as kingdoms.
Archaea differ from the true bacteria in many important respects, as well as from the eukaryotes.
www.wikiwhat.com /encyclopedia/a/ar/archaea.html   (559 words)

  
 archaea
The structure and function of the genes in archaea are surprisingly similar to the structure and function of the genes in eukaryotes, while those of eubacteria are not.
Archaea are thought to be among the earliest terrestrial life-forms to have evolved, survivors from a time when the environment on Earth would have been too hostile to allow anything other than extremophiles to develop (see Earth, early history).
It may be that archaea, and other varieties of extremophiles, are commonly the first to colonize young planets and that as time goes by they retreat to those regions, such as hydrothermal vents and subsurface rocks, where primordial environments remain.
www.daviddarling.info /encyclopedia/A/archaea.html   (423 words)

  
 The Story of Archaea
Bacteria and archaea are unicellular prokaryotes (lacking a nucleus).
Archaea are found in many harsh environments on the planet, and have adapted to live at extremes of temperature (from Polar ice to superheated water), pressure, pH (from extreme acid pH 0 to alkaline pH 10) and salinity (saturated NaCl in salt pans and the Dead Sea).
Archaea constitute a major portion of the biosphere, and are also present in soil, temperate sea water and even the human gut.
waterindustry.org /Water-Facts/archaea-3.htm   (691 words)

  
 archaea
Archaea are found in many harsh environments on the planet, and have adapted to live at extremes of temperature (from Polar ice to superheated water), pressure, pH (from extreme acid pH 0 to alkaline pH 10) and salinity (saturated NaCl in salt pans and the Dead Sea).
So archaea are often called "Extremophiles", but they also constitute a major portion of the biosphere, and are also present in soil, temperate sea water and even the human gut.
Most hyperthermophiles are archaea, and the most extreme are crenarchaea.
www.st-andrews.ac.uk /~mfw2/archaea.htm   (0 words)

  
 The Archaea
Archaea differ from bacteria in that they have histone proteins associated with their DNA as we do.
Though many Archaea (singular Archaeon) live in environments which are hazardous to most other organisms, some live much closer to us and species of Archaea have been found in animal, including in the human, digestive tract.
The Archaea are a diverse and fascinating group of micro-organisms and the Korarchaeota (one of the group's main divisions) may contain the most ancient of living things and therefore are the closest thing we have to our original 'ancestral organism'.
www.earthlife.net /prokaryotes/archaea.html   (0 words)

  
 Nearctica - Natural History - Archaea
The Archaea have historically been considered part of the bacteria (they are sometimes called the Archaebacteria), but recent work has shown them to be very distinct.
A common nickname for the Archaea is "Extremophiles".
Although the Archaea break down into four distinct evolutionary lines, three major groups are recognized on the basis of their physiology.
www.nearctica.com /nathist/miscanim/archaea.htm   (0 words)

  
 Ammonia-loving archaea win landslide majority
Archaea are single-celled microbes that, along with bacteria, comprise a category of small organisms whose genetic material, or DNA, is not stored in a nucleus (as it is in animals and plants).
During a recent study of a collection of genes in microorganisms, researchers had stumbled on a particular gene, which is responsible for the production of a key enzyme used for the oxidation of ammonia.
The gene was subsequently found in a marine strain of archaea that uses ammonia as its sole source of energy.
www.eurekalert.org /pub_releases/2006-08/ps-aaw081606.php   (0 words)

  
 From hot springs to rice farms, scientists reveal new insights into the secret lives of archaea
Indeed, many species of archaea thrive in environments that would kill other organisms, from Yellowstone hot springs to the hyper-salty Dead Sea to streams polluted by mining waste where the pH level is equivalent to battery acid.
''Archaea have been a pretty hot topic for a number of years in the microbial ecology and physiology realm,'' Francis said, noting that most biology textbooks now divide life into three domains-Archaea, Bacteria and Eukarya, a category that includes plants, animals, fungi, algae and protozoa.
Although archaea are believed to be among the oldest organisms on Earth, finding paleontological evidence of these ancient microbes has proven elusive.
www.eurekalert.org /pub_releases/2006-12/su-fhs120706.php   (0 words)

  
 The Archaea Group
Thus, by studying the archaea, it may be possible to deduce properties of the earliest cellular organisms.
Archaea therefore provide insights into the origin of the eukaryotes, and provide simple model systems for complex eukaryal processes, in particular for the transcription and replication machineries.
Extremophiles and applied science Many archaea are extremophiles that thrive under conditions of extreme heat, acidity, salinity and/or pressure, and there is intense industrial interest in archaea as sources of thermostable enzymes and other biomolecules of unusual properties.
artedi.ebc.uu.se /molev/resarch/archaea.html   (842 words)

  
 World Builders: Archaea -- Early earth life forms. E Viau CALSTATE
It is believed that the archaea may be the oldest life forms on earth, and that the bacteria and eukaryotes have evolved from them and with them, at least in part.
The relationships are still being studied, and right now the scientists think that perhaps the early archaea and bacteria may have been the survivors of a pool of life forms that were all in the early stages of their evolution.
The members of the archaea are tiny prokaryotes that look a lot like bacteria, and, until Dr. Carl Woese at the University of Illinois started studying their DNA sequences, no one had guessed that these little prokayrotes were a separate group of living things.
leda.calstatela.edu /courses/builders/lessons/less/les4/archaea.html   (619 words)

  
 Leigh Lab : Archaea
Archaea constitute one of the three domains in the Woesian tree of life along with Bacteria and Eukarya.
Archaea are generally like Bacteria in size and shape and can be found in many of the same environments.
Archaea are distinct from Bacteria in the possession of a simplified version of the transcriptional apparatus that is characteristic of Eukaryotes, and they can serve as model systems for the study of the eukaryal transcription apparatus.
faculty.washington.edu /leighj/mmarchaea.html   (198 words)

  
 Archaea - Biocrawler   (Site not responding. Last check: 2007-11-07)
However, their genetic transcription and translation - the two central processes in molecular biology - do not show the typical bacterial features, but are extremely similar to those of eukaryotes.
However, other archaeans are mesophiles, and have been found in environments like marshland, sewage, and soil.
Some have suggested that eukaryotes arose through fusion of an archaean and eubacterium, which became the nucleus and cytoplasm, which accounts for various genetic similarities but runs into difficulties explaining cell structure.
www.biocrawler.com /encyclopedia/Archaea   (891 words)

  
 Untitled Document
Some microbiologists suggest that the archaea domain sits between that of the prokaryotes and that of the eukaryotes, but the current main-stream view is as shown below, which is based on ribosomal DNA analysis.
The plasma membranes in Archaea are different from those found in other organisms and are made from lipid-like materials.
As with prokaryotes the genetic strands - DNA - of archaea float freely in the cell.
www.theguardians.com /Microbiology/gm_mbf05.htm   (278 words)

  
 Archaea   (Site not responding. Last check: 2007-11-07)
The major physiological groups within the Archaea (informally, archaes) are extreme thermophiles (including thermoacidophiles), sulfate reducers, methanogens, and extreme halophiles.
This is largely because the methanogens have given rise to multiple other groups, including the halophiles, the sulfate reducers, and at least two other lineages of nonmethanogenic thermophiles.
The thermophilic members of the Archaea include the most thermophilic organisms cultivated in the laboratory, some having optimal growth at > 100 °C. The aerobic thermophiles are also acidophilic; they oxidize sulfur in their environment to sulfuric acid, creating acid hot springs.
lecturer.ukdw.ac.id /dhira/ClassAndPhylo/archaea.html   (516 words)

  
 Archaea
Archaea was originally thought to be just another form of bacteria, but archaea is a much simpler form of life, simpler than a single-celled organism, which nevertheless contains DNA, the gene-code of life.
Archaea may be the oldest and oddest form of life.
Other Archaea species are not extremophiles and live in ordinary temperatures and salinities.
www.windows.ucar.edu /tour/link=/life/archaea.html&edu=high   (303 words)

  
 Aetiology: Archaea as human pathogens?
The archaea have received a lot of attention as "extremophiles:" the microbes that live in environments that have high salinity, very high or low temperatures, or other extremes that make the processes of life daunting.
A paper in the April issue of the Journal of Clinical Microbiology reports the identification of archaea in tissue from infected teeth.
Though these data obviously aren't conclusive regarding a role played by archaea in disease causation, they are suggestive of one, especially in conjunction with the findings in the current article.
scienceblogs.com /aetiology/2006/05/archea_as_human_pathogens_1.php   (2103 words)

  
 WebQuest
Since Brock's initial discovery of Archaea in hot springs, scientists have found Archaea living in all sorts of harsh conditions-in the Dead Sea, in sewage sludge, on the ocean floor, in the gut of cows.
Archaea look like bacteria under a microscope, but scientists do not consider them to be true bacteria.
A type of Archaea known as strain 121 was found in a vent on the floor of the Pacific Ocean at a depth of 1.5 miles.
highered.mcgraw-hill.com /sites/0078664276/student_view0/unit4/webquest.html   (1217 words)

  
 Domain Archaea
Species of the domain Archaea are not inhibited by antibiotics, lack peptidoglycan in their cell wall (unlike bacteria, which have this sugar/polypeptide compound), and can have branched carbon chains in their membrane lipids of the phospholipid bilayer.
It is believed that Archaea are very similar to prokaryotes that inhabited the earth billions of years ago.
Therefore, it is believed that the domains Archaea and Bacteria branched from each other very early in history, and membrane infolding produced eukaryotic cells in the archaean branch approximately 1.7 billion years ago.
www.sidwell.edu /us/science/vlb5/Labs/Classification_Lab/Archaea   (167 words)

  
 Archaea research
Many Archaea live in hostile environments, from salt lakes to acidic hot springs, but they can be very difficult to grow and study in the laboratory.
The use of naturally occurring arsenic by Archaea and certain types of bacteria has serious consequences in some parts of the world, because the process converts the arsenic to a more toxic form that is also more likely to remain dissolved in water.
Many Archaea are poisoned by oxygen and have to be grown in special airtight containers.
currents.ucsc.edu /05-06/11-28/archaea.asp   (948 words)

  
 Archaea - Gurupedia
The Archaea may be treated as a single kingdom or as a
Arachaea also include the methanogens in their number, the only organisms known to produce methane, which are one of the several possible explanations for the recently discovered presence of methane on Mars.
The Archaea appear to be close relatives of the eukaryotes, and some work has suggested that the Euryarchaeota may be closer to them than the Crenarchaeota, though more recent studies support their monophyly.
www.gurupedia.com /a/ar/archaea.htm   (525 words)

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