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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]
I greatly admire Lynn Margulis's sheer courage and stamina in sticking by the endosymbiosis theory, and carrying it through from being an unorthodoxy to an orthodoxy. I'm referring to the theory that the eukaryotic cell is a symbiotic union of primitive prokaryotic cells.
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]
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 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.
This theory is analogous to the accepted theory for the origin of eukaryotic mitochondria and chloroplasts, which are thought to have developed from a similar endosymbiotic relationship between proto-eukaryotes and aerobic bacteria. [68]
Ivan Emanuel Wallin (22 January 1883 – 6 March 1969) [1] was an American biologist who made the first experimental works on endosymbiotic theory. [2] Nicknamed the "Mitochondria Man", he claimed that mitochondria, which are cell organelles, were once independent bacteria, as supported by his comparative studies and culture of isolated mitochondria. [3]