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An overview of the endosymbiosis theory of eukaryote origin (symbiogenesis). Symbiogenesis theory holds that eukaryotes evolved via absorbing prokaryotes. Typically, one organism envelopes a bacterium and the two evolve a mutualistic relationship. The absorbed bacteria (the endosymbiont) eventually lives exclusively within the host cells.
The original theory by Lynn Margulis proposed an additional preliminary merger, but this is poorly supported and not now generally believed. [1] Symbiogenesis (endosymbiotic theory, or serial endosymbiotic theory [2]) is the leading evolutionary theory of the origin of eukaryotic cells from prokaryotic organisms. [3]
Reductive evolution [4] is the basis behind the Endosymbiotic Theory, which states that Eukaryotes absorbed other microorganisms (Eukaryotes and archaea) for their metabolites produced. The absorbed organisms undergo reductive evolution, deleting genes that were deemed nonessential or non-beneficial to the cell in its specific niche in the host.
The endosymbiotic theory implies rare but major events of saltational evolution by symbiogenesis. [79] Carl Woese and colleagues suggested that the absence of RNA signature continuum between domains of bacteria, archaea, and eukarya shows that these major lineages materialized via large saltations in cellular organization. [80]
The theory of endosymbiosis, as known as symbiogenesis, provides an explanation for the evolution of eukaryotic organisms. According to the theory of endosymbiosis for the origin of eukaryotic cells, scientists believe that eukaryotes originated from the relationship between two or more prokaryotic cells approximately 2.7 billion years ago.
The hydrogen hypothesis is a model proposed by William F. Martin and Miklós Müller in 1998 that describes a possible way in which the mitochondrion arose as an endosymbiont within a prokaryotic host in the archaea, giving rise to a symbiotic association of two cells from which the first eukaryotic cell could have arisen (symbiogenesis).
The theory proposes the process through which these organelles evolved within the ancestors of eukaryotic organisms through the formation of an endosymbiotic relationship between a bacteria and an archaea This idea is that the ancient Archaean organism engulfed a bacteria that possessed aerobic capabilities.
Fungal-bacterial endosymbiosis encompasses the mutualistic relationship between a fungus and intracellular bacteria species residing within the fungus. Many examples of endosymbiotic relationships between bacteria and plants, algae and insects exist and have been well characterized, however fungal-bacteria endosymbiosis has been less well described.