endosymbiont theory

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endosymbiont theory

[‚en·dō′sim·bē‚änt ‚thē·ə·rē]
(cell and molecular biology)
A theory that the mitochondria of eukaryotes and the chloroplasts of green plants and flagellates originated as free-living prokaryotes that invaded primitive eukaryotic cells and become established as permanent symbionts in the cytoplasm.
References in periodicals archive ?
The late Lynn Margulis explains endosymbiotic theory and the evolutionary importance of symbiotic relationships between organisms from dissimilar phyla or kingdoms.
Margulis' revolutionary work in biology earned her prestige in the field with her theory on the origin of eukaryotic organelles and her contributions to the endosymbiotic theory.
However, ever since a seminal event in the far past--it's hypothesized in the Endosymbiotic Theory that one prokaryotic (non-nucleated, single cellular bacteria) organism engulfed another one and rather than just digesting it, began a productive co-association--there have actually been two (or more) distinct genome partitions in eukaryotic cells.