Organisms in the Domains Bacteria and Archaea


Discuss the similarities and differences between organisms in the domains Bacteria and Archaea


Organisms in the Domains Bacteria and Archaea

Archaea were formerly classified as bacteria with the name archaebacteria due to a number of similarities between them and bacteria. It is only after careful studies that scientists discovered the distinct biochemistry and evolutionary history between them (Pommerville, 2014). There are a number of similarities between archaea and bacteria. To start with, archaea and bacteria have basically the same size, shape and appearance. Secondly, both of the organisms multiply through binary fission which is a form of asexual reproduction. Thirdly, the primary means by which both organisms move is through the use of flagella. Fourthly, both are classified as prokaryotes since they lack a complex cell structure common among eukaryotes. Lastly, they both contain semi-permeable cell membranes that allow selective movement of elements or substances through them (Pommerville, 2014).

There are a number of differences found between archaea and bacteria that sets them apart. One of the notable differences is that bacteria have cell walls which contain peptidoglycan, which is a polymer consisting of amino acids and sugars (Pommerville, 2014). Archaea cell walls are made up of pseudopeptidoglycan, which partly comprise of N-acetyltalosaminuronic acid. There exist differences in the type of lipid bonding that occurs in the membranes of bacteria and archaea. Archaea membrane lipids are held together by ether bonds while in bacteria ester bonds occur. Archaeal lipids do not have fatty acids which are common in bacteria. Instead, the lipids are made up of side chains which comprise of isoprene units. The RNA in archaea is more complex to the one found in bacteria. Bacteria contain simple RNA polymerases. They also contain metabolic differences. Bacteria use glycolysis to breakdown glucose while archaea use a different process. Lastly, majority of Archaea lack the Kreb’s Cycle pathways which is common in bacteria (Pommerville, 2014).


Pommerville, J. C. (2014). Fundamentals of microbiology. Burlington, MA: Jones & Bartlett       Learning.

Genetic Drift