How does endo symbiosis play a role in the evolution of prokaryotes to eukaryotes and how are mitochondria important to this evolution?

EndosymbiOSis is the process where one organism lives inside another. In the evolution of eukaryotes, it is believed that a prokaryotic cell engulfed a smaller prokaryotic cell, forming a symbiotic relationship. This led to the development of organelles like mitochondria. Mitochondria are crucial in eukaryotic evolution because they produce energy for the cell through respiration, allowing for more complex cellular functions to evolve.