Endosymbiosis:
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Endosymbiosis, or the Endosymbiotic Theory, is defined as “a process in which unicellular organisms (the “host”) engulfs the other cell” (Reece, Campbell, Cain, Urry, Minorsky, Wasserman & et al, 2011 pp. 516). This idea of phagocytosis via endosymbiosis is said to be the cause of the divergence of the first heterotrophic eukaryotic cells. Green alga and red alga are a result of this process. Plastids are said to be decedents of particular cyanobacteria called “Protochlorophytes” ( Heldt, 1997 pp. 13). The definition of endosymbiosis, as it relates to algae is that the Cyanobacteria, or Protochlorophyte symbiont, were phagocytized into an established host (heterotrophic eukaryote).