Give a description of the three basic types of Archaebacteria. What makes them unique in the global flora?

Question

Give a description of the three basic types of Archaebacteria. What makes them unique in the global flora and fauna?

Answer 1

The Archaea [ɑrˈkiə] (help·info) are a group of single-celled microorganisms. A single individual or species from this domain is called an archaeon (sometimes spelled "archeon"). Archaea, like bacteria, are prokaryotes and have no cell nucleus or any other organelles within their cells. In the past they were viewed as an unusual group of bacteria and named archaebacteria but since the Archaea have an independent evolutionary history and show many differences in their biochemistry from other forms of life, they are now classified as a separate domain in the three-domain system. In this system, introduced by Carl Woese, the three main branches of evolutionary descent are the Archaea, Eukaryota and Bacteria. Archaea are further divided into four phyla of which two, the Crenarchaeota and the Euryarchaeota, are most intensively studied. Classifying the Archaea is still difficult, since the vast majority of these organisms have never been studied in the laboratory and have only been detected by analysis of their nucleic acids in samples from the environment.

Generally, archaea and bacteria are quite similar in size and shape: although a few archaea have very unusual shapes, such as the flat and square-shaped cells of Haloquadra walsbyi. Despite this visual similarity to bacteria, archaea possess genes and several metabolic pathways that are more closely related to those of eukaryotes: notably the enzymes involved in transcription and translation. Other aspects of archaean biochemistry are unique, such as their reliance on ether lipids in their cell membranes. The archaea exploit a much greater variety of sources of energy than eukaryotes: ranging from familiar organic compounds such as sugars, to using ammonia, metal ions or even hydrogen gas as nutrients. Salt-tolerant archaea (the Halobacteria) use sunlight as a source of energy, and other species of archaea fix carbon; however, unlike plants and cyanobacteria, no species of archaea is known to do both. Archaea reproduce asexually and divide by binary fission, fragmentation, or budding; in contrast to bacteria and eukaryotes, no species of archaea are known that form spores.

Initially, archaea were seen as extremophiles that lived in harsh environments, such as hot springs and salt lakes, but they have since been found in a broad range of habitats, such as soils, oceans and marshlands. Archaea are particularly numerous in the oceans, and the archaea in plankton may be one of the most abundant groups of organisms on the planet. These prokaryotes are now recognized as a major part of life on Earth and may play an important role in both the carbon cycle and nitrogen cycle. No clear examples of archaeal pathogens or parasites are known, but they are often mutualists or commensals. One example are the methanogenic archaea that inhabit the gut of humans and ruminants, where they are present in vast numbers and aid in the digestion of food. Archaea have some importance in technology, with methanogens used to produce biogas and as part of sewage treatment, and enzymes from extremophile archaea that can resist high temperatures and organic solvents are exploited in

The classification of archaea, and of prokaryotes in general, is a rapidly moving and contentious field. Current classification systems aim to organize archaea into groups of organisms that share structural features and common ancestors.[9] These classifications rely heavily on the use of the sequence of ribosomal RNA genes to reveal relationships between organisms (molecular phylogenetics).[10] Most of the culturable and well-investigated species of archaea are members of two main phyla, the Euryarchaeota and Crenarchaeota. Other groups have been tentatively created. For example, the peculiar species Nanoarchaeum equitans, which was discovered in 2003, has been given its own phylum, the Nanoarchaeota.[11] A new phylum Korarchaeota has also been proposed, it contains a small group of unusual thermophilic species that shares features of both of the main phyla, but is most closely related to the Crenarchaeota.[12][13] Other recently detected species of archaea are only distantly related to any of these groups, such as the Archaeal Richmond Mine Acidophilic Nanoorganisms (ARMAN), which were discovered in 2006.[14]



The ARMAN are a new group of archaea recently discovered in acid mine drainage.The classification of archaea into species is also controversial. In biology, a species is a group of related organisms. A popular definition of a species in animals is a set of organisms that can breed with each other and are reproductively isolated from other groups of organisms (i.e. they cannot breed with other species).[15] However, efforts to classify prokaryotes such as archaea into species are complicated by the fact that they are asexual and show high levels of horizontal gene transfer between lineages. The area is contentious; with, for example, some data suggesting that in archaea such as the genus Ferroplasma, individual cells can be grouped into populations that have highly-similar genomes and rarely transfer genes with more divergent groups of cells.[16] These groups of cells are argued to be analogous to species. On the other hand, studies in Halorubrum found significant genetic exchange between such populations.[17] Such results have led to the argument that classifying these groups of organisms as species would have little practical meaning.[18]

Current knowledge on the diversity of archaea is fragmentary and the total number of archaean species cannot be estimated with any accuracy.[10] Even estimates of the total number of phyla in the archaea range from 18 to 23, of which only 8 phyla have representatives that have been grown in culture and studied directly. Many of these hypothetical groups are known from only a single rRNA sequence, indicating that the vast majority of the diversity among these organisms remains completely unknown.[19] The problem of how to study and classify uncultured microbes is also encountered in the Bacteria.[20]

their Origin and evolution,morphology,cell structure,cell membrane,metabolism,genetic,ecology,habi... in chemical cycling,Interactions with other organisms,Significance in technology and industry all these things are explained in detail with pictures i dont mind copy pasting ti here...but will take loadsa space sorry...hope thishelped you :)

Answer 2

The Archaea are divided into 3 main phylums

http://www.cas.muohio.edu/~stevenjr/mbi2...

Euryarchaeota (salt tolerant Halophiles, Methanogens- methane producers, and acid tolerant Acidophiles)

http://www.tolweb.org/Euryarchaeota/10

http://www.earthlife.net/prokaryotes/eur...

Crenarchaeota (Thermophiles in heat or in cold as Cryophiles)

http://www.earthlife.net/prokaryotes/cre...

http://www.tolweb.org/Crenarchaeota/9

Korarchaeota recently discovered and little is known but are also thermophiles.

http://www.jgi.doe.gov/sequencing/why/34...

http://www.textbookofbacteriology.net/pr...

Archaea are able to colonize and survive in humans but are not known to cause any diseases.

http://iai.asm.org/cgi/content/full/71/2...