Over the past century, several scientists around the world have made the following observations New mitochondna and plastids can only be generated by old mitochondria and plastids through a process similar to bin fission Both mitochondria and plastids contain DNA that is similar in shape and size to that of bacteria and plastids are surrounded by two or more membranes whose composition is similar to a prokaryotic membrane Mitochondria and plastids are about the same size as bacteria These observations scientists to conclude