From Extracellular to Intracellular: The Establishment of Mitochondria and Chloroplasts

• Published in: Proceedings of the Royal Society of London. Series B, Biological sciences Biological sciences, 1979-04, Vol.204 (1155), p.165-187
• Main Authors: Whatley, Jean M., John, P., Whatley, F. R.
• Format: Article
• Language: English
• Subjects: Adenosine Diphosphate - metabolism; Adenosine Triphosphate - metabolism; Algae; Bacteria; Bacterial Physiological Phenomena; Cell membranes; Chloroplasts; Chloroplasts - physiology; Cyanobacteria - physiology; Cytochrome c Group - physiology; Cytochromes; Daughter cells; Mitochondria; Mitochondria - physiology; Paracoccus; Paracoccus - physiology; Photosynthesis; Plant cells; Plants; Rhodopseudomonas - physiology; Species Specificity; Symbionts; Symbiosis
• ISSN: 0962-8452; 0080-4649; 0950-1193; 1471-2954; 2053-9193
• DOI: 10.1098/rspb.1979.0020

Paracoccus and Rhodopseudomonas are unusual among bacteria in having a majority of the biochemical features of mitochondria; blue-green algae have many of the features of chloroplasts. The theory of serial endosymbiosis proposes that a primitive eukaryote successively took up bacteria and blue-green algae to yield mitochondria and chloroplasts respectively. Possible characteristics of transitional forms are indicated both by the primitive amoeba, Pelomyxa, which lacks mitochondria but contains a permanent population of endosymbiotic bacteria, and by several anomalous eukaryotic algae, e.g. Cyanophora, which contain cyanelles instead of chloroplasts. Blue-green algae appear to be obvious precursors of red algal chloroplasts but the ancestry of other chloroplasts is less certain, though the epizoic symbiont, Prochloron, may resemble the ancestral green algal chloroplast. We speculate that the chloroplasts of the remaining algae may have had a eukaryotic origin. The evolution of organelles from endosymbiotic precursors would involve their integration with the host cell biochemically, structurally and numerically.