Endosymbiosis Theory

The start of any evolutionary story told about us lies within the origin of the eukaryote cell. This remarkable event consisted of a revolution of cell type matched in momentousness by the arrival on the biological scene of the prokaryote (O’Malley). Bacteria had a couple billion years head start on eukaryotes and have given rise to many biochemical processes that are essential to the ecosystem (Wernergreen). One organism living within another defines endosymbiosis. Nobody can say the exact origin of the eukaryote cell. The endosymbiosis theory dates back to the earliest 20th century and devotion to different models of its origins is strong and adamant (O’Malley).

This theory was developed from the combined efforts of many different researchers. Together, Konstantin Mereschkowsky, Boris Mikhaylovich Kozo-Polyansky, Ivan Wallin, and Lynn Margulis are the main researchers whom coined the term “symbiogenesis” referring to the long term, or permanent physical association between “differently named partners” (taxa), or the genesis of new species through the merging of two or more existing species (Margulis). Endosymbiosis and symbiogenesis define hypothetical theories thought to justify the origin of species in addition to the processes of natural selection and random mutation. B.M. Kozo-Polyansky and Lynn Margulis, who very much admired Kozo-Polyansky’s work, both believed symbiogenesis was the major source of innovation for evolution (Margulis). The most well known of the first speculations about the origin of organelles, was Mereschkowsky. He primarily studied the chloroplast and was the first to suggest they were obtained initially from unicellular organisms that had been “enslaved” as endosymbionts. However, his theory was turned ...

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...hemical energy from cyanobacteria (the only bacteria that can perform photosynthesis) 2.4 billion years ago (Wernergreen). The first chloroplast came into being about one billion years ago when a single-celled protist and a cyanobacterium came together through endosymbiosis, and this first photosynthesizing eukaryotic lineage was the ancestor of land plants, green algae, and red algae. Cyanobacteria and algae endosymbionts have spread photosynthetic capabilities in such a broad range (Wernergreen). In other words, heterotrophic prokaryote cells had taken in autotrophic photosynthetic bacteria cells. The ingested cell continued to provide glucose and oxygen by photosynthesis. The host cell protected as well as provided carbon dioxide and nitrogen for the engulfed cell and overtime both cells lost the aptitude to survive without each other (Weber and Osteryoung).