Hypothesize whether prokaryotic cells might have been symbiotic before the evolution of eukaryotic

 Two prokaryotes turning into a eukaryotic cell began with a process called

endosymbiosis. One large prokaryote engulfs (a process called

endocytosis) one small, aerobically respiring prokaryote. The small

prokaryote turned into a membrane-bound organelle, which prokaryotes do

not have, and like we know, only eukaryotes have membrane-bound

organelles. So that is how the eukaryotic cell structure evolved from

prokaryotic cells, meaning that before this evolution, they were most likely symbiotic.