Prokaryotes, Eukaryotes, and Endosymbiotic Theory

There are many theories as to how life began here on Earth, one theory states that microorganisms from space came to Earth in the ice of comets.  Others state that the oceans were a "primordial soup" with all of the building blocks of life already present with a mix of gases and lightning which came together in just the right way to form the beginnings of life. 

No matter how life began, it did.  I would like to begin here.  With the very first cells on Earth.