Describe the first step that may have led toward cellular organization

Cellular organization: Refers to all components of the cell and how they are arranged to perform their specific functions.

It has been suggested that all organisms originate from a single primordial cell. I think the first step in cellular organization began with the postulation that eukaryotic cells evolved from the endosymbiosis of prokaryotic cells giving them the double-layered membrane and organelles.

formation of microspheres might have been the first step toward cellular organization (found this somewhere)