The answer is Domain. It is also referred to as Superkingdoms. There are three domains in current classification system namely; Archaea, Bacteria, and Eukarya. The first two classify single-celled organisms whose cells have no nucleus while Eukarya classifies organism that have a nucleus bound by a membrane. The difference between Archaea and Bacteria is their membrane structure; Archaea’s membrane is characterized by membrane lipids that are branched hydrocarbon chains attached to glycerol by ether linkages, while Bacteria’s is made of unbranched fatty acid chains attached to glycerol by ester linkages.
