In nuclear physics, nuclear fission is either a nuclear reaction or a radioactive decay process in which the nucleus of an atom splits into smaller parts (lighter nuclei). The fission process often produces free neutrons and releases a very large amount of energy.
Thus, The Nuclear Fission is caused by the impact of Neutrons.
Prokaryotic cells lack a nucleus and do not have an extensive system of interior membranes. They are encased in a cell wall and many contain external structures such as a capsule, flagellum, or pili. Prokaryotes – have a relatively uniform interior that is not subdivided by internal membranes.