Abundant evidence has been found for endosymbiosis: 1. Mitochondria and chloroplasts are similar in size and morphology to bacterial prokaryotic cells, though the mitochondria of some organisms are known to be morphologically variable. 2. Mitochondria and chloroplasts divide by binary fission, just as bacteria do, and not by mitosis as eukaryotes do. Both types of organelle have Fts proteins at their division plane.