Endosymbiosis and the Evolution of Eukaryotes

What is endosymbiosis?The topic that was brought before is about cell theory.But how do cell form?There are a few main point to explain how the cell form itself.

Endosymbiosis is the concept of one cell engulfing another and both cells benefiting from the relationship.

Endosymbiosis was originally considered after the observation of the similarity between plant chloroplasts and free-living cyanobacteria.

Endosymbionts may have transferred some of their DNA to the host nucleus, thus becoming dependent on the host for survival and completing full integration into a single organism.

The Endosymbiotic Hypothesis

The endosymbiotic hypothesis concerns the origin of mitochondria and chloroplasts, two organelles contained within various eukaryotic cells.  According to this hypothesis, these organelles originated as separate prokaryotic organisms that were taken inside a primordial eukaryotic cell.  Such symbiotic relationships in which two species are dependent upon one another to varying extents served as crucial elements of the evolutionary progression of eukaryotic cells.