What is endosymbiotic theary?

Answer 1

This theory tries to explain the double membranes belonging to mitochondria and chloroplasts. It suggests that both organelles once used to be single organisms, as in they were not mere parts of a cell.

Answer 2

The endosymbiotic theory proposes that eukaryotic cells evolved from a symbiotic relationship between different types of bacteria. Specifically, it suggests that mitochondria and chloroplasts within eukaryotic cells were originally free-living prokaryotes that were engulfed by a larger host cell but were not digested, eventually forming a mutually beneficial relationship. This theory is widely accepted as an explanation for the presence of these organelles in eukaryotic cells.