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bharathi's picture

The inner organization of the living cell, consisting of specialized organelles, makes complex forms of life possible...we all know about mitochondria..and prokaryotes... but can anyone explain  the origin of the mitochondria and their connection to the prokaryotes?.....

Fraser Moss
Fraser Moss's picture
Ivan Delgado
Ivan Delgado's picture

The prevailing theory about the origin of mitochondria is that they used to be bacteria that somehow developed a symbiotic relationship with another cell. Some of the observations that lead to this theory include: 
1. Their genome. Mitochondrial genomes are circular structures that resemble the plasmids found in bacteria.
2. The fact that mitochondria contain their own genome even though they exist inside a cell suggest they used to be a free-living organism. There is evidence that mitochondrial are losing their genes (they are migrating to the cell's nucleus), another fact that suggest mitochondria used to live outside cells
3. Mitochondria reproduce by binary fission, just like bacteria. Actually all your mitochondria came from your mother (every mitochondria in your body traces its lineage to the mitochondria found in the female egg)
4. Even their shape: unlike typical eukaryotic cells, mitochondria tend to be more rod-like, just like some bacteria
Of course this is just a hypothesis, but a very compelling one indeed.