Evolutionary origin of chloroplasts and mitochondria

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The evolutionary origins of the mitochondria and chloroplasts have been accepted and believed to have evolved from an event which occurred a long time ago. Scientists noticed that there was a huge resemblance with the mitochondria, chloroplasts and bacteria cells. They noticed that the DNA in the two organelles was organised in the same way as a DNA from a bacterial cell also mitochondria and chloroplasts also reproduce independently from the cells in which they reside, in a manner very like bacterial fission. "Many microbiologists think it is likely that mitochondria and chloroplasts were once free-living prokaryotes (cells that lack a nucleus and organelles) that somehow took up residence in larger cells. An Invading bacterium may have infected a cell, then become a permanent resident as it adapted to become less virulent, or the target cell became less susceptible. Or both” [1]. It has been accepted that the two organelles evolved from free living oxygen metabolizing bacteria (aerobic) that were engulfed by an ancestral eukaryotic cell (was anaerobic). The mitochondria and chloroplasts have two membranes supporting this theory. The inner membrane was most likely derived from the original bacteria membrane,whereas the outer membrane is a remenant of the plasma membrane from the engulfment. These features play a vital role in the functions of the two cellular power stations [2]


  1. [American society for Microbiology (2006) Mitochondria and Chloroplasts. Available at: http://archives.microbeworld.org/microbes/mergers/mitochondria.aspx Accessed: 17th November 2014
  2. [Harvey Lodish (and 8 others) by W.H.FREEMAN and company. (2013) Molecular cell biology, 7th edition, New York and England: W.H. FREEMAN AND COMPANY & Macmillan Higher Education .]

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