It is presumed that mitochondria were primitive aerobic prokaryotes that were engulfed in mutualism by primitive anaerobic eukaryotes, receiving protection from these beings and offering energy to them. This hypothesis is called the endosymbiotic hypothesis on the origin of mitochondria.
The hypothesis is strengthened by some molecular evidence such as the fact that mitochondria have their own independent DNA and protein synthesis machinery, with their own RNA and ribosomes, and that they can self-replicate.
The endosymbiotic theory can be applied to chloroplasts too. It is supposed that these organelles were primitive photosynthetic prokaryotes because they have their own DNA, RNA and ribosomes and they can self-replicate too.
The hypothesis is strengthened by some molecular evidence such as the fact that mitochondria have their own independent DNA and protein synthesis machinery, with their own RNA and ribosomes, and that they can self-replicate.
The endosymbiotic theory can be applied to chloroplasts too. It is supposed that these organelles were primitive photosynthetic prokaryotes because they have their own DNA, RNA and ribosomes and they can self-replicate too.
