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.
Joule isunit of work or energy in the International System of Units (SI) which is equal to the work done by a force of one newton acting through one metre.