Division of Endosymbiotic Organelles

ScienceWeek: "Like their free-living ancestors, both chloroplasts and mitochondria divide. Organelle division, segregation, and growth are often uncoupled from the cell division cycle, indicating that organelle and cell division are independent processes. Division of mitochondria and chloroplasts is orchestrated by multicomponent protein machines that assemble and drive the constriction and fission of the organellar membranes. Because both organelles are surrounded by inner and outer membranes that differ in composition, their division machines must accomplish the synchronized constriction of both membranes, the subsequent fusion of the four lipid bilayers, the final separation of the two daughter organelles, and possibly the resolution of the fused membranes back into two discrete bilayers."