Between 4.1 and 3.5 billion years ago
Prokaryotes are unicellular, do not possess cell organelles, lack membrane bound nucleus, histone proteins, contain 70's ribosome.
prokaryotes
Archaea
Prokaryotes differ with other organisms in they don't have definite nucleus, nuclear envelop is absent. nucleolus is absent. no mitosis instead they show amitosis mediated by divisomes ( septasome )...