Both bacteria and archaea are organisms consisting of a single cell that lacks a nucleus or organelles. Even though these two groups are evolutionarily unique, there are a number of similarities. It is easy to see why archaea were once considered a type of bacteria.
All living organisms belong to one of three groups, or domains. These domains are Archaea, Bacteria and Eukaryota. Eukaryotic organisms have cells that contain a nucleus and other organelles bound by individual membranes. Animals, plants and fungi are all eukaryotes. Archaea and Bacteria are prokaryotic cells — they contain no membrane-bound organelles. Both groups do, however, contain ribosomes. Ribosomes consist of RNA and protein and create all the proteins necessary for a cell’s survival. Bacteria and Archaea are both capable of movement, and accomplish this via flagella. Both types of organisms are also both surrounded by a cell wall. The two prokaryotic domains reproduce through asexual reproduction. There are three methods common to both domains: binary fission, fragmentation and budding. In binary fission, cells double their size then split evenly, creating equal-sized daughter cells. In fragmentation, a new cell grows from a severed piece of the parent cell. In budding, a new organism develops from some point on the parent organism. Due to asexual reproduction, the offspring of Archaea and Bacteria are genetic copies of the parent.