Which theory explains the origins of some organelles in eukaryotic cells as formerly free-living prokaryotic microbes?

The endosymbiotic theory is a widely accepted explanation for the origin of certain organelles in eukaryotic cells, specifically mitochondria and chloroplasts. This theory posits that these organelles originated from free-living prokaryotic cells that entered into a symbiotic relationship with ancestral eukaryotic cells. Over time, these prokaryotic cells became integral parts of the eukaryotic cells, losing their ability to survive independently.

Evidence supporting the endosymbiotic theory includes the fact that mitochondria and chloroplasts possess their own DNA, which is circular and resembles that of prokaryotes, as well as the presence of double membranes surrounding these organelles. These features suggest that they were once independent bacteria that were engulfed by a host cell. Additionally, the replication of mitochondria and chloroplasts occurs through a process similar to binary fission, which is characteristic of prokaryotes.

In contrast, cell theory primarily focuses on the idea that all living organisms are composed of cells, while gene theory pertains to how traits are passed from one generation to another through genes. Evolutionary theory, broadly defined, encompasses the mechanisms by which species change over time but does not specifically address the origin of