The mitochondrial genome, transcriptional and translation systems closely resemble bacterial systems, rather than the nuclear genome of the same organism. This is strong evidence that the mitochondrial genome, and probably the entire organelle, evolutionarily derive from a heterotrophic bacterium that became an endosymbiont in a simple eukaryotic cell. A very few known eukaryotes lack mitochondria, these are generally parasites of other eukaryotes. No other animal organelles are known to contain autonomous genomes or translation systems, although there has been speculation that some of the other organelles may once have contained genomes and have derived from endosymbiotic events. In plants, as in animals, membrane translation occurs on the endoplasmic reticulum and on the mitochondrial inner membrane.
Chloroplasts perform light energy capture to drive photosynthetic electron transport.
Plastids, like mitochondria, contain a genome. In fact, the chloroplast genome is considerably larger than most mitochondrial genomes and encodes many of the key proteins involved in photosynthetic electron transport and and carbon dioxide fixation. In general these proteins form parts of complexes along with proteins encoded by the nuclear genome and imported from the cytosol. This is one way the nuclear genome contributes to the regulation of chloroplast protein synthesis. Chloroplast Translation Membrane translation in chloroplasts occurs on the thylakoid membrane systems, which absorb light and couple the energy to drive electron transport and ATP production.