Prokaryotes vs. Eukaryotes

Prokaryotes and eukaryotes are two classifications of living things based on cellular composition. They are mutually exclusive, meaning that every living thing that is not a prokaryote is a eukaryote.

Prokaryotes are a kingdom that consists of mainly single-celled organisms with no distinct nucleus or organelles contained by a membrane. They can be broken into two domains: bacteria and archaea. It is believed that prokaryotes were the only organisms on Earth for millions of years.

Eukaryotes are organisms consisting of one or more cells that contain a nucleus and organelles contained by a membrane. They can be organized into complex structures such as humans. All living things except for prokaryotes (bacteria and archaea) are eukaryotes.

The distinction between prokaryotes and eukaryotes is one of the most important among groups of organisms. All living things except for prokaryotes share a similar cellular structure consisting of a nucleus with DNA and other organelles.