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Graham Smith Bio 205 Final Project Archaea “Archaea” are a diverse group of “bacteria-like” (prokaryotes/no nucleus) and are often considered a major group unto themselves. This group is called the Archaea (from Greek, „old‟) for short and to distinguish them from the other prokaryotes, all other bacteria are then called Eubacteria.” source: http://www.bacteriamuseum.org/niches/evolution/evolution.shtml one classification system as dsiplayed on: http://honeybee.helsinki.fi/users/gjurgens/Archaea/archaea.htm According to the above diagram, the Archaeans are not bacteria at all, but exist in an entirely exclusive domain composed of halophiles(salt-loving Archaeans) and thermophiles (Archeans that habitate environments of extreme temperature). Ecology Archaeans are often discovered in “extreme” environments. Many archaeans live in extremely acidic or alkaline conditions. Others inhabit deep sea rift vents where temperatures are in excess of 100 degrees Centigrade. Recently, Archaean icrobes were discovered here in Northern Indiana. Contaminated groundwater created from years of steel slag dumping provided an extremely alkaline environment in which these particular Archaeans have probably been thriving for years. “ ‟Just how the unusual bacteria got to the slag dumps is currently a mystery,‟ says Roadcap. „ I‟d hate to hazard a guess,‟ he said, regarding their origins. One possibility is that local bacteria adapted to the extreme environment over the last century. Another possibility is that they somehow got imported. As for whether the unexpected microbial community has any effect on the extensive groundwater archaeans are often called “nature’s extremists”because of the oustandingly dynamic environments they inhabit such as the hotspring shown above. http://calvin.st-andrews.ac.uk/external_relations/down_loads/archaea-brilliant_but_small.jpg contamination problem in the slag dumps, „ We have not come to any conclusion about that,‟ says Roadcap. Among the possible harmful things microbes could do is collect and distribute hazardous materials to nearby lakes and wetlands. But so far that has not been documented.” (Department of Geology – UIUC. http://www.geology.uiuc.edu/news_info/RoadcapAlkaline.html ) “Although many archaea are extremophiles, direct rDNA amplification from environmental samples has made it clear that the archaea are widespread also in non-extreme biotopes. Thus, they have ecological significance for large-scale circulation of energy, nutrients and biomass, as well as for the greenhouse effect, since all biologically released methane (several hundred million tons annually) is produced by archaea.” http://artedi.ebc.uu.se/molev/resarch/archaea.html Human beings have had a tremendous effect on the domain Archaea and have even created some of their many habitats. As discussed above, slag dumping in “the region” (NW Indiana/Chicago/Lake Michigan area) has resulted in extremely contaminated groundwater which serves as a supportive ecosystem for a few different Archaeans. Reproduction Archaeans reproduce asexually. Binary fission (simple cell division) is utilized. Molecular and Cellular Information There is much debate over how to classify Archaeabacteria, or the “Archaeans.” Because these organisms are prokaryotic, many scientists wish to call them bacteria. However, other professionals maintain that Archaeans are as different from bacteria as humans are when it comes to biochemistry and genetics. I will use both terms when referring to the organisms in question in this project. Archaeans have no nucleus as implied by the frequent prokaryotic classification. They resemble other bacteria in many ways, but there also exist critical differences. Archaeans “are more similar to Eukaryotes than to bacteria in several ways: their cell-wall does not contain peptidoglycan (a component of each bacterial cell)...) http://www.bacteriamuseum.org/niches/evolution/evolution.shtml The Archaea are predominantly unicellular. The cell does not(like other prokaryotes) contain a nucleus. It also does not contain membrane-bound organelles. Archaean cells are capable of growth at temperatures exceeding 80 degrees Celcius. Histone proteins and gas vesicles are present. An Archaean cell is capable of Denitrification, Nitrogen fixation, and Chemolithotrophy. Genetics/Evolution In Archaeans, DNA occurs in circular form. Operons( gene clusters under common control in bacteria.) are also present. pewagbiotech.org/resources/glossary/ . Archaeans have no nucleus and DNA is stored free-floating within the cell membrane. According to scientists Archeans have been on the scene since the dawn of time. “ In the universal phylogenetic tree, all the shortest and deepest branches consist of hyperthermophiles. This suggests that the last common ancestor of all life on Earth was a hyperthermophile, and most hyperthermophiles are archaea. Thus, by studying the archaea, it may be possible to deduce properties of the earliest cellular organisms. It has also been suggested that the eukaryotic lineage originated from a series of cellular fusions between different bacteria and archaea. 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.” http://artedi.ebc.uu.se/molev/resarch/archaea.html ebiomedia.com/ prod/images/Tree2.jpg Most scientists maintain that as the Earth changed over the years, Archaeans were by far one of the most adaptable groups of unicelluar organisms on the planet. This accounts for their extreme adaptibility to extreme environments. The question is raised, however, as to whether the Archaens are an invasive species in such environments as the slag dumps mentioned above. Archaeans most definitely affect other organisms, but the effects are largely indirect due to the fact that these “Slag-Archaeans” were found deep in the ground. The real invasive species in this instance would be human beings. It was, indeed, humans that polluted the groundwater. Closing The domain Archaea was not recognized until recently. In previous times scientists classified organisms as either plants or animals. With the development of the domains “Bacteria” and “Eukaryota” scientists were forced to place the Archaeans in one of these categories. However, this task was not so easy as it was found that the Archaens shared characteristics with both bacteria and eukaryotes. Thus, the domain “Archaea” was born. The archaens are unique in that they inhabit such extreme environments. Research is still uncovering new information about these fascinating organisms and much speculation continues as to why Archaens choose such “strange” circumstances in which to exist.
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