Archaea VS Bacteria
Should Bacteria and Archaea belong to the same Kingdom?
The main purpose of this essay is to find out if Archaea and Bacteria should be classified as two different Kingdoms or as a single one. As organisms, bacteria and archaea both are microscopic and prokaryotic (not possessing a true nucleus). These prokaryotes are very abundant on Earth and inhabit a wide spread of areas, including extreme ones. Both are an example of the most ancient living cells, which have appeared over 3.5 billion years ago. Correct classification of these organisms is important in order to trace the evolutionary history from the very beginning and make a clearer picture of the common ancestor, if it existed. This work will explain the basic taxonomy principles and compare some of the main similarities and differences between archaea and bacteria.
Taxonomy is a section of science which puts organisms into biological groups and names them, based on their characteristic features. The history of this science started when ancient Greek and Roman scientists classified certain animal and plant species known to them (http://www.nhm.ac.uk). Since that time, the way of classifying organisms has changed several times, as the ways of gathering information about the species improved. Scientists of different times proposed their own ways of classification schemes which included the four-Kingdom version with Monera, as a collective name for prokaryotic organisms (Scamardella, 1999). This was followed by five-Kingdom classification by Whittaker (1969), again introducing Kingdom Monera, which became very popular that time. However, some scientists opposed the initial dichotomic division of organisms into prokaryotes and eukariotes. Woese (1977) proposed the three-domain or six-Kingdom division, where Kingdom Eubacteria and Kingdom Archaea were classified separately (see Figure 2). Overall, there was no united opinion about Kingdoms in the 20th century. Terms, such as "urkingdoms", "superkingdoms"
The main purpose of this essay is to find out if Archaea and Bacteria should be classified as two different Kingdoms or as a single one. As organisms, bacteria and archaea both are microscopic and prokaryotic (not possessing a true nucleus). These prokaryotes are very abundant on Earth and inhabit a wide spread of areas, including extreme ones. Both are an example of the most ancient living cells, which have appeared over 3.5 billion years ago. Correct classification of these organisms is important in order to trace the evolutionary history from the very beginning and make a clearer picture of the common ancestor, if it existed. This work will explain the basic taxonomy principles and compare some of the main similarities and differences between archaea and bacteria.
Taxonomy is a section of science which puts organisms into biological groups and names them, based on their characteristic features. The history of this science started when ancient Greek and Roman scientists classified certain animal and plant species known to them (http://www.nhm.ac.uk). Since that time, the way of classifying organisms has changed several times, as the ways of gathering information about the species improved. Scientists of different times proposed their own ways of classification schemes which included the four-Kingdom version with Monera, as a collective name for prokaryotic organisms (Scamardella, 1999). This was followed by five-Kingdom classification by Whittaker (1969), again introducing Kingdom Monera, which became very popular that time. However, some scientists opposed the initial dichotomic division of organisms into prokaryotes and eukariotes. Woese (1977) proposed the three-domain or six-Kingdom division, where Kingdom Eubacteria and Kingdom Archaea were classified separately (see Figure 2). Overall, there was no united opinion about Kingdoms in the 20th century. Terms, such as "urkingdoms", "superkingdoms"
References: Brooker, R. J., Widmaier, E. P., Graham, L. E., Stiling, P. D. 2014 Biology 3rd edition, New York: McGraw-Hill Education Bryant, D Cary, N. C. 2009 New Foundations of Evolution: On the Tree of life, New York: Oxford University Press Cavicchioli, R Kato, S. Y. 2011 Microbiology Research Advances: Archaea: Structure, Habitats and Ecological Significance, New York: Nova Science Publishers Kelman, L Woese, C. R., Fox, G. E. 1977 Phylogenetic structure of the prokaryotic domain: the primary kingdoms. Proc Natl Acad Sci, 74(11), 5088-90, available from: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC432104/, [accessed on 19/02/2015]