Definitions for "Endosymbiosis"
When one organism takes up permanent residence within another, such that the two become a single functional organism. Mitochondria and plastids are believed to have resulted from endosymbiosis.
The hypothesis that mitochondria and chloroplasts are the descendants of ancient prokaryotic organisms from the domain Bacteria.
A mutually beneficial relationship between two organisms in which one, the endosymbiont, lives within the tissues or the cells of the other, the host.