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Topic: Endosymbiosis


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  Symbiosis - Open Encyclopedia   (Site not responding. Last check: 2007-11-06)
An example of mutual symbiosis is the relationship between clownfish of the genus Amphiprion (family, Pomacentridae) that dwell among the tentacles of tropical sea anemones.
The biologist Lynn Margulis, famous for the work on endosymbiosis, contends that symbiosis is a major driving force behind evolution.
She considers Darwin's notion of evolution, driven by competition, as incomplete, and claims evolution is strongly based on co-operation, interaction, and mutual dependence among organisms.
open-encyclopedia.com /Symbiosis   (522 words)

  
 The Serial Endosymbiosis Theory of Eukaryotic Evolution
The term "endosymbiosis" specifies the relationship between organisms which live one within another (symbiont within host) in a mutually beneficial relationship.
This discovery served to demonstrate that endosymbiosis could provide a major mechanism for cellular evolution and explain the introduction of new species (Jeon 1991).
ecent research by Martin and Müller (1998) into the origin of the mitochondrion has led to a new theory of endosymbiosis called the "hydrogen hypothesis." In the current picture of the origin of the eukaryotic cell, the mitochondrion was a "lucky accident" (Vogel 1998).
www.geocities.com /jjmohn/endosymbiosis.htm   (2294 words)

  
 Comment on "The Evolution of Modern Eukaryotic Phytoplankton" -- Keeling et al. 306 (5705): 2191b -- Science   (Site not responding. Last check: 2007-11-06)
This endosymbiont was reduced and integrated, and part of this process involved the transfer of hundreds of genes from the cyanobacterium/plastid to the eukaryotic host nucleus (red arrow).
A single endosymbiosis involving a red alga probably gave rise to the chromalveolates (yellow); this group is supported by several molecular characters and gene trees (plotted on the figure).
The ancestor of red algae must have had at least this many genes, but this does not necessarily mean that the genome of the ancestor (or ancestors) of secondary red algal plastids retained all of these genes.
www.sciencemag.org /cgi/content/short/306/5705/2191b   (1416 words)

  
 Genome Biology | Full text | Phylogenomic evidence supports past endosymbiosis, intracellular and horizontal gene ...   (Site not responding. Last check: 2007-11-06)
The apicoplast is a relict plastid hypothesized to have been acquired by an ancient secondary endosymbiosis of a pre-alveolate eukaryotic cell with an algal cell [8].
In apicomplexans that have a plastid, many of the original plastid genes appear to have been lost (for example, photosynthesis genes) and some genes have been transferred to the host nuclear genome; their proteins are reimported into the apicoplast where they function [12].
Plastids acquired by secondary endosymbiosis are scattered among eukaryotic lineages, including cryptomonads, haptophytes, alveolates, euglenids and chlorarachnions [13-17].
genomebiology.com /2004/5/11/R88   (7219 words)

  
 Endosymbiosis
That force may be hidden in the process of endosymbiosis, the process by which a new organism originates from the fusion of two existing organisms, or, more precisely, by which two independently evolved organisms become a tightly coupled system and eventually just one organism.
The American biologist Lynn Margulis is perhaps the strongest proponent of endosymbiosis.
Margulis' fundamental thesis is that our bodies are amalgams of several different strains of bacteria: endosymbiosis of bacteria is responsible for the creation of complex forms of life.
www.thymos.com /science/endosymb.html   (2233 words)

  
 Journal of Systematic Biology--Volume 8, Number 2
The third theory of serial endosymbiosis relies on symbiogenesis, or long term symbiotic relationships between different species that lead to new forms of life.
Evidence given by the authors (Raven and Johnson, 1996; Dyer and Obar, 1994; Winckner et.al., 1986) states that the chloroplast followed the mitochondria in endosymbiosis is that chloroplasts are to use the glucose and starch that they produce without the aid of mitochondria.
To test for endosymbiosis, nuclei were extracted from infected amoebae and inserted into normal amoebae.
comenius.susqu.edu /bi/202/Journal/Vol8/number2/dragonfliespub.htm   (1539 words)

  
 margulis
With the benefit of hindsight it is easy to smile at the comparison between continental drift and endosymbiosis, two great scientific heresies that later revolutionized the way we look at the natural world.
She was also writing her first book on endosymbiosis, which sparked a lively controversy when it was published in 1970.
According to the traditional view, evolution usually occurs gradually; endosymbiosis, however, is based on the idea of rather sudden evolutionary changes.
www.msu.edu /course/lbs/145/luckie/margulis.html   (2265 words)

  
 Brainstorms: Endosymbiosis and science
Her first paper, "Origin of Mitosing Cells" makes it clear that the lion's share of her attention was devoted to the centrioles, where she even went so far to argue that centromeres were of bacterial origin.
Suffice it to say that the main thrust of her hypothesis has been rejected by mainstream science, where endosymbiosis currently accounts for the origin of mitochondria and chloroplasts, not eukarya (although some now favor a symbiosis these between archaea and eubacteria).
Since endosymbiosis is a common phenomena, how does this square with a "single endosymbiotic origin of mitochondria?" It would seem to me that a polyphyletic origin follows more naturally from the basic tenets of the serial endosymbiosis thesis.
www.iscid.org /boards/ubb-get_topic-f-6-t-000236.html   (1064 words)

  
 ENDOSYMBIOTIC THEORY   (Site not responding. Last check: 2007-11-06)
Simply stated, the theory of endosymbiosis is the concept that mitochondria and chloroplasts are the result of years of evolution initiated by the endocytosis of bacteria and blue-green algae which, instead of becoming digested, became symbiotic.
Factors in favor of mitochondrial and chloroplast endosymbiosis.
If the theory of endosymbiosis is true, then one must ask what was the original eukaryotic cell (without mitochondria or chloroplasts) and how did it survive (glycolysis?).
www.mrs.umn.edu /~goochv/CellBio/lectures/endo/endo.html   (492 words)

  
 Darwinism Refuted.com
Unsurprisingly, it was criticized by scientists who carried out very important research into the subject on a number of grounds: We can cite D. Lloyd332, M. Gray and W. Doolittle333, and R. Raff and H. Mahler as examples of these.
The endosymbiosis hypothesis is based on the fact that the mitochondria of animal cells and the chloroplasts of plant cells contain their own DNA, separate from the DNA in the nucleus of the parent cell.
While the situation envisioned by the endosymbiosis hypothesis is occurring through a process of trial and error, what effects would this have on the DNA of the parent cell?
www.darwinismrefuted.com /origin_of_plants_02.html   (1011 words)

  
 Endosymbiosis
Symbiosis is an association between two or more species, and endosymbiosis implies that one species was living inside the other one, the host.
The prokaryotes that gave rise to all eukaryotes were probably from the domain Archaea because both noticeable characteristics and DNA comparison suggest that these monerans are more closely related to the eukaryotes.
According to one theory that is widely supported, mitochodrion evolved from small heterotrophic prokaryotes that were engulfed by a larger eukaryotic cells (where membrane infolding had occurred).
www.sidwell.edu /us/science/vlb5/Labs/Classification_Lab/Bacteria/symbiosis.html   (525 words)

  
 Endosymbiosis and The Origin of Eukaryotes
Sequencing of the apicoplast DNA shows that its genome is closely related to that of the chloroplasts of green algae (and thus of all green plants).
All of this indicates that the apicoplast is the product of an ancient endosymbiosis in which the eukaryotic ancestor engulfed a unicellular green alga with a solitary chloroplast.
Over time, the nucleus was lost (no residual nucleomorph) as well as many features of the chloroplast (including its ability to perform photosynthesis).
users.rcn.com /jkimball.ma.ultranet/BiologyPages/E/Endosymbiosis.html   (1344 words)

  
 Continued evolutionary surprises among dinoflagellates -- Morden and Sherwood 99 (18): 11558 -- Proceedings of the ...
(5) A eukaryotic cell with a secondary plastid is engulfed by a nonphotosynthetic eukaryote (tertiary endosymbiosis).
(4) Secondary endosymbiosis of green alga with retention of algal nucleus as nucleomorph between second and third layers of plastid membrane.
(6) Secondary endosymbiosis of red alga by cryptophyte with retention of algal nucleus (nucleomorph) between second and third layers of plastid membrane.
www.pnas.org /cgi/content/full/99/18/11558   (2105 words)

  
 Science Forums and Debate - Case for future endosymbiosis.   (Site not responding. Last check: 2007-11-06)
Endosymbiosis, the theory that says that plastids such as mitochondria and chloraplasts are actually the decendents of bacteria that entered into a symbiotic relationship with other cells.
The prediction made by my professor was the possibility of these bacteria one day becoming just as much a part of the plant as mitochondria.
So what we have is a possible case for future endosymbiosis.
www.scienceforums.net /forums/printthread.php?t=7303   (195 words)

  
 Endosymbiosis - The Appearance of the Eukaryotes
The hypothesized process by which prokaryotes gave rise to the first eukaryotic cells is known as endosymbiosis, and certainly ranks among the most important of evolutionary milestones.
Under this theory, the prokaryotes that gave rise to all eukaryotes were probably from the domain Archaea both because several key characteristics and DNA comparison suggest that Archaeans are more closely related to the eukaryotes than are eubacteria.
This is the so-called serial endosymbiosis theory of a monophyletic origin of the mitochondrion from a eubacterial ancestor.
www.fossilmuseum.net /Evolution/Endosymbiosis.htm   (275 words)

  
 Botany online: Evolution - Energy-Conversion - Eucaryotes
The ability of large and cell wall-less eucaryotic cells to take up organic material led also to their taking up smaller cells, a process called phagocytosis.
Phagocytosis may in some cases not have resulted in the digestion of the smaller cells, but in a symbiosis with them, a state also known as endosymbiosis.
The large differences in the pigmentation and the ultrastructure of the chloroplasts of red algae, brown algae, diatoms, and green plants make a single incident as the initiation of endosymbiosis unlikely.
www.biologie.uni-hamburg.de /b-online/e42/42c.htm   (2860 words)

  
 BioMed Central | Full text | A genomic timescale for the origin of eukaryotes
Based on the serial endosymbiosis theory, the first symbiotic event involved a spirochete [3].
This result was consistent with the serial endosymbiosis theory [3] and with other findings [6] and therefore we designated this divergence as BK-o (origin of eukaryotes).
Estimation of the divergence time of the origin of plastids (BK-p) was not a goal of this study, and the LCA was not estimated because of an insufficient number of duplicate proteins needed for reciprocal rooting [23].
www.biomedcentral.com /1471-2148/1/4   (4994 words)

  
 Chlorophyta Lecture   (Site not responding. Last check: 2007-11-06)
There are no chloroplasts, or the entire cell can be viewed as a chloroplast.
*endosymbiosis between eukaryotic heterotroph predator and eukaryotic autotrophic prey
*endosymbiosis between eukaryotic heterotroph and eukaryotic autotrophic prey
www.lander.edu /rsfox/300chlorophtLec.html   (1137 words)

  
 Endosymbiosis   (Site not responding. Last check: 2007-11-06)
Molecular Evolution - Endosymbiosis and endosymbiotic gene transfer...
Endosymbiosis and genome evolution, Molecular Evolution Workshop at the MBL, Aug...
AltaVista Search: Simple Query endosymbiosis Autopoiesis symbiogenesis microbial...
www.scienceoxygen.com /biology/82.html   (129 words)

  
 Eukaryotes
Endosymbiosis is undoubtedly a fascinating concept and, at first glance, the evidence appears to support it as the mechanism for the evolution of chloroplasts and mitochondria.
Furthermore, most of the mitochondrial genes can also be found in the nucleus (endosymbiosis proponents explain this as leaping genes).
The size of ribosomes in organelles varies among eukaryotes (60-80S) and while that does overlap with prokaryotic ribosomes (70S for eubacteria) it also overlaps with the cytoplasmic ribosomes of eukaryotes (78-80S).
www.gwu.edu /~darwin/BiSc151/Eukaryotes/Eukaryotes.html   (1609 words)

  
 SET and Organelles
Endosymbiosis = concept in biology in which one or more organisms lives inside another organism
Successive mergers (secondary endosymbiosis) added structural and functional features, such as new organelles, to the resulting cells.
Because of commentary and criticism from Max Taylor and other generous colleagues the serial endosymbiosis theory prevailed.
www.lionden.com /set_and_organelles.htm   (1327 words)

  
 AltaVista Search: Simple Query endosymbiosis Autopoiesis symbiogenesis microbial ...   (Site not responding. Last check: 2007-11-06)
A traditional book has covers, a table of contents, chapters so is linear and fixed in time and space.
In an effort to bolster their life-in-outer-space theory, scientists and engineers from around the world were meeting in Pasadena on Wednesday and Thursday to discuss an exploration of Lake Vostok, a subglacial lake under the ice in Antarctica which they believe has conditions similar to Europa's sea.
endosymbiosis Autopoiesis symbiogenesis microbial Protoctists life margulis Mitochondria microcosmos microcosm bacterial microbiology molecular microbial microorganisms microorganism biology evolutionary lovelock gaia biosphere sagan gaian biology biochemistry genetics pathogenesis bacterium organism enzyme protein enzymes pathogenic viruses anaerobic bacteria evolutionary evolution rna dna ecology ecosystem ecosystems ecological molecular systematics microbes organisms organism genetically genetic
members.tripod.com /wiredbrain/weblife.htm   (1632 words)

  
 The theory of endosymbiosis
Coursework and Essays: By Subject: Biology: The theory of endosymbiosi
Below is a short sample of the essay "The theory of endosymbiosis".
If you sign up you could be reading the rest of this essay in under two minutes.
www.coursework.info /i/14233.html   (461 words)

  
 Molecular Evolution - Endosymbiosis and endosymbiotic gene transfer
Plastids and mitochondria were once free-living prokaryotes - at the time of endosymbiosis they possessed all genes necessary for that free-living lifestyle.
Deane JA, Fraunholz M, SuV, Maier U-G, Martin W, Durnford DG, McFadden GI (2000): Evidence for nucleomorph to host nucleus gene transfer: light-harvesting complex proteins from cryptomonads and chlorarachniophytes.
Henze K, Schnarrenberger C, Martin W (2001) Endosymbiotic gene transfer: A special case of horizontal gene transfer germane to endosymbiosis, the origins of organelles and the origins of eukaryotes.
www.molevol.de /research/endosymbiosis.html   (431 words)

  
 Algae--Chapter 7   (Site not responding. Last check: 2007-11-06)
Endosymbiosis and the Origin of Eukaryotic Algae with a focus on Glaucophytes, Chlorarachniophytes, and Apicomplexans
endosymbiosis, chlorarachniophytes as examples of a group that originated by
secondary endosymbiosis, and dinoflagellates as exemplars of tertiary
www.botany.wisc.edu /cryptogams/graham/chapter7.html   (124 words)

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