Symbiogenesis

Evolutionary theory

Symbiogenesis, also known as the endosymbiotic theory or serial endosymbiotic theory,) is the leading scientific theory for the evolutionary origin of eukaryotes from prokaryotic ancestors. The theory holds that multi-membraned eukaryotic organelles such as mitochondria and chloroplasts are endosymbionts descended from formerly free-living prokaryotes (more closely related to the Bacteria than to the Archaea) that were phagocytized into another prokaryote's endomembrane system. Mitochondria appear to be phylogenetically related to Alphaproteobacteria such as Rickettsiales, while chloroplasts are thought to be related to beta-cyanobacteria.

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