A Critical Analysis Of The Theory Of Endosymbiosis And It...

A critical analysis of the Theory of Endosymbiosis and it’s supporting evidence Abstract Introduction The endosymbiotic theory is an evolutionary theory explaining the origin of Eukaryotic cells from Prokaryotic, and is at present; the most widely accepted evolutionary theory of the Eukaryotic cell. The theory explains the origins of mitochondria and chloroplasts and their double membranes, suggesting that chloroplasts and mitochondria represent formerly free-living bacteria that were taken into a cell as an endosymbiont. Molecular evidence suggests that mitochondria developed from proteobacteria and chloroplasts from cyanobacteria. It is thought that the Prokaryotes may have entered the host cell as a parasite or source of nutrient for the host, however avoided digestion. The primitive chloroplast may have provided the host cell with crucial nutrients, and the primitive mitochondrion may have aided the exploitation of oxygen for the extraction of energy. In return the host cell offered a protected environment for the Prokaryotes to live in. This was the beginning of a symbiotic rela tionship between the primitive chloroplast and mitochondria, and the Eukaryotic cell. The theory was ridiculed for years due its controversial nature, however in 1967 Lynn Margulis, a biologist from Boston University, developed the modern Serial Endosymbiosis Theory. Primary Endosymbiosis vs. Secondary Endosymbiosis Primary endosymbiosis involves the engulfment of a bacterium by another