What is the evidence for endosymbiotic theory?
Evidence that mitochondria and plastids arose from ancient endosymbiosis of bacteria is as follows: New mitochondria and plastids are formed only through a process similar to binary fission. In some algae, such as Euglena, the plastids can be destroyed by certain chemicals or prolonged absence of light without otherwise affecting the cell. In such a case, the plastids will not regenerate. They are surrounded by two or more membranes, and the innermost of these shows differences in composition from the other membranes of the cell. The composition is like that of a prokaryotic cell membrane. Both mitochondria and plastids contain DNA that is different from that of the cell nucleus and that is similar to that of bacteria (in being circular in shape and in its size). DNA sequence analysis and phylogenetic estimates suggests that nuclear DNA contains genes that probably came from plastids. These organelles’ ribosomes are like those found in bacteria (70s). Proteins of organelle origin, like
