Comparing Organisms in the Domains Bacteria and Archaea (Essay Sample)

Similarities and Differences
Name
Institution
Similarities and Differences
The two domains are neither ancestor to each other; however, they do have several similarities among the two and differences are present as well. The two domains, bacteria, and archaea are found in the prokaryotes division. The organisms in the two domains have been found to have similarities that make them classified into one category but the differences they have made them different enough to be differently classified. The organisms in the two domains are both single-celled as well as ubiquitous in nature. They are found to be present in many places in the world. They lack the complexity of the eukaryotes (Lane & Martin, 2010).
The organisms in the archaea domain are similar to organisms in the bacteria domain regarding shape, size as well as appearance (Garrity, 2012). They are both unicellular, and they are therefore microscopic, often having sizes equating to micrometers in diameter as well as in length. Giving the example, halobacteria, archaea, is about five micrometers long while a cocci can be about 0.2 micrometers. The organisms in both domains have been found to have similar shapes, each having diverse and strange forms such as flat or square-shaped cells for the archaea or the star-shaped cells of rectangular cells as is for some bacteria. It should be noted that where the organisms from both domains have the same shape, it becomes difficult to differentiate the two when being studied under a microscope.
It is also difficult to tell the two organisms apart due to their morphological similarities. The organisms in both domains lack a true membrane-bound nucleus. Thus, the nucleic acid is found to be free in the cytoplasm of the cell. The nucleic acid is mainly the double-stranded DNA, which is a circular molecule though some bacteria may have plasmids (Adams, 2012). The organisms have a cell wall, and cell membrane but the variation comes in the chemical composition of the cell wall. The cell walls are the ones that support the flagella, fimbriae, and other external structures. Organisms from both domains use the flagella as they primary means of movement. The two domains are similar to each other since the organisms multiply asexually by binary fission, whereby the resulting daughter cells are alike to the parental cell.
There are differences between the two domains. The cell wall composition for the bacteria includes the peptidoglycan, which is lacking in the cell wall of the archaea. They have several types that include the pseudo peptidoglycan. The cell membranes also differ from one another, where bacteria’s contains ester linkage while the archaea’s contains ether bonds. The archaea’s external structures especially the plasma membranes are made up of different and unusual lipids to enable them to survive in the extreme conditions they inhabit. The ribosomal RNAs of the organisms in the domains differ as well as the numbers of RNA polymerases. It should be noted that the archaeal ribosomes work much more like the eukaryotic ones than those found inside a bacterial cell.
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