Study
The origin and diversification of mitochondria
Roger, Andrew J.; Muñoz-Gómez, Sergio A.; Kamikawa, Ryoma
Current Biology, 2017
Reviews phylogenomic placement of the mitochondrial ancestor among bacteria, the extensive transfer of genes from the organelle to the host nucleus, and the diversity of mitochondrion-related organelles across eukaryotes.
- Studied in
- Eukaryota, Alphaproteobacteria
- Sample size
- review of phylogenomic and comparative evidence
Mitochondria descend from a bacterial lineage, retain only a small remnant genome, and have transferred most ancestral genes to the host nucleus. Their forms vary widely across eukaryotes, including highly reduced organelles that no longer respire.
What it means
The authors' reading, and ours. Where they differ, that difference is the point.
How the authors put it
Mitochondrial origin is settled in outline; the identity of the closest bacterial relatives and the order of events remain under investigation.
How NatureHQ reads it
The record that keeps the popular phrasing honest. "Mitochondria used to be bacteria" is a statement about ancestry, and it is true in that sense. A mitochondrion today is not a bacterium living in a cell: most of its genes are in the host nucleus, it cannot live independently, and it has been reduced and rebuilt over roughly two billion years. Descent from is not the same as a captive example of.
- A review; the precise bacterial sister lineage remains actively debated.
- The nature of the host cell at the time of the event is much less well constrained than the bacterial side.
What this study is used for on NatureHQ
One study can inform several subjects. Here is everywhere this one is cited.
Endosymbiosis
Mitochondria descend from free-living bacteria taken up by an ancestral cell. They are not bacteria now: most of their genes moved to the host nucleus, and none can live independently.
Endosymbiosis
No single observation established endosymbiosis. Own DNA, own division, double membranes, bacterial-type ribosomes and phylogenetic placement each point the same way for separate reasons.
Published by: Cell PressPublished in a Cell Press journal.
doi.org/10.1016/j.cub.2017.09.015
Checked against Crossref on 2026-09-28, and they agree on the title, the authors and the year.
NatureHQ summarises research in its own words and does not reproduce published text. Reviewed 2026-09-04.