The presence of double-membrane structures in mitochondria and chloroplasts similar to bacterial cells supports the theory of endosymbiOSis.
The existence of circular DNA in mitochondria and chloroplasts, similar to bacterial DNA, provides evidence of their bacterial origin.
Phylogenetic studies reveal that the genetic material in mitochondria and chloroplasts is more closely related to certain groups of bacteria than to eukaryotic nuclear DNA, supporting their evolutionary history as once-independent organisms.
