Theories on Cell Fusion Essay -- Biology Microbiology

Theories on Cell Fusion Endosymbiotic theory commonly asserts that the eukaryotic endomembranes and cytoskeleton originated and formed a type of proto-eukaryotes that started engulfing and using other prokaryotes, thus explaining the presence of bacterial genes in mitochondria. Many scientists are now contesting this idea based on new data. This new data shows that some of the machinery for transcription and translation of DNA may be from archaea, instead of the theory that most or all genetic information came from an engulfed bacterial cell. â€Å"In particular, it is turning out that eukaryotic nuclear genomes carry many genes of bacterial (sometimes à ¡-proteobacterial) origin which have nothing to do with mitochondrial functions.† (2) The tree of life may not necessarily be correct when it shows Eukarya coming off either the bacterial or archaeal branch of the tree. Instead, we are proposing that new theories suggesting genomic fusion may be more accurate. The relationship may have started out through necessity, which lead to increased surface contact and eventual lateral gene transfer. Scientists not only have evidence that this may have happened instead of endosymbiosis, but also reasons why cell fusion may have occurred. Martin and Muller think that the excretion of hydrogen and carbon dioxide by à ¡-proteobaceria benefited methane-producing archaeans that used hydrogen and carbon dioxide as sources of energy and carbon. â€Å"In the absence of an outside source of hydrogen, the Archaean (nominally the host) became dependent on the à ¡-proteobacterium (the symbiont). Selection of host genes produced tighter and tighter physical association and greater surface contact between the two.† (2) Researchers recently used thirt... ...wo prokaryotes. In addition, we are not trying to determine in this short paper whether Archaea or Bacteria evolved first; instead, we are simply stating that the endosymbiosis theory of Lynn Marguiles leaves far too many gaps in the foundation of eukaryotic existence for it too be widely accepted without any further examination. Works Cited: (1)†Complex Cells Likely Arose from Combination of Bacterial and Extreme Microbe Genomes.† NSF Press Release. 8 Sept 2004. http://www.nsf.gov/od/lpa/newsroom/ (2)Doolittle, W. Ford. â€Å"A Paradigm Gets Shifty.† Nature. Volume 392. 5 Mar 1998. (3)Lake, James; Rivera, Maria. â€Å"The Ring of Life provide evidence for a genome fusion origin of eukaryotes.† Nature. Volume 431. 9 Sept 2004. (4)Embley, T. Martin; Martin, William. â€Å"Early Evolution Comes Full Circle.†