The endosymbiotic theory states that some of the organelles in eukaryotic cells were once prokaryotic microbes. Mitochondria and chloroplasts are the same size as prokaryotic cells and divide by binary fission. Mitochondria and chloroplasts have their own DNA which is circular, not linear.
THREE observations that support the endosymbiotic theory. Mitochondria/chloroplast contain their own DNA. Mitochondria/chloroplast can self-replicate. -chromosomes are circular.