Domain Archaea: Archaea were discovered in the 1970’s by Dr.Carl Woese and his coworkers at the University of Illinois. At first, Dr. Woese thought that archaea were just bacteria, but then realized that there were differences between the two domains, for instance: Archaea live in places with extreme environments,they produce methane, usually gathered together in groups, they have very different genetic makeup than that of bacteria and eukaryotes. Archaea were at first called Archaebacteria, but the name was later changed to just Archaea because, well, it’s Archaea, and not bacteria. Even though Archaea are known to live in hostile environments, they also have been found to live in open ocean waters among smaller organisms like plankton [1].
Domain Bacteria: Bacteria were discovered by Van Leeuwenhoek. Something that Van Leeuwenhoek discovered while he was researching bacteria, was that there are more bacteria in a single human mouth than people in the world. Many bacteria release exotoxins that react very badly with human the body or sometimes they have glycoproteins on the outside of their capsules. There are three main shapes of bacteria. The first shape is Cocci. Cocci are spherical, prokaryotic cells. The second shape is Bacilli. Bacilli take on the shape of a rod. The third shape is Spirochete. Spirochete are spiral shaped [2].
Domain Eukarya: Domain Eukarya was discovered 1.7 billion years ago. To classify an organism as eukarya, the organism must have a series of characteristics. For instance, an organism must have many modes of accessing energy and carbon dioxide(dependant on the kingdom), it must have “Eukaryotic cells”, it must be unicellular, multicellular, colonial, and they must have membrane organelles. It is important to understand how the Eukaryotic endomembrane system came to be through membrane infolding. In this process there are around three steps. 1. The plasma membranes of the first prokaryotic cells that brought about the first eukaryotic membranes, folded inward 2.This created the endoplasmic reticulum after the inwards projections of the plasma membrane were pinched off [3].
Similarities: There are many similarities between the three domains. For instance there are similarities between Archaea and Bacteria. They both resemble each other in shape and size, they both cannot be seen with the naked eye, and they both have flagella [4].While there are a few similarities between Archaea and Bacteria, there are also some similarities between Archaea and Eukaryotes. They are both not sensitive to antibiotics, they both have the same first amino acid during protein synthesis: Methionine, and they both have histones [5]. Although, Archaea and Eukaryotes have some things in common, Bacteria and Eukaryotes also have some things in common. They (sometimes in the case of Eukaryotes) both have a cell wall and they both contain rRNA [6].
Differences: There are many differences between the three domains. Archaea is a bit different than bacteria and eukaryotes in the sense that Archaea have different lipid bonds compared to bacteria and eukarya [7]. Bacteria can cause illnesses or cure them, Archae help scientists to learn about genetics, and Eukarya help scientists to learn about new species of animals and plants [6]. Bacteria can be found in moderate environments, Archaea grow in extreme environments, and Eukarya tend to have the ability to grow just about anywhere [8].
