Archaea and bacteria are generally single-celled organisms which represent two of the three domains of life. Although these two domains are now recognized as independent, this was not always the case. Previously these groups were referred to as Eubacteria and Archaebacteria. It was in the 1970s that archaea were discovered as a completely new group of organisms1.
The term Archaebacteria became inappropriate to use once it was discovered that archaea are actually quite different genetically and in terms of their biochemistry, from bacteria. Although, under the microscope these two types of organisms look to be rather similar.
Archaea are really unique organisms which are capable of living in very extreme environments, such as deep-sea vents, hot springs and very acidic waters. Similar to bacteria, they have been found in the digestive tracts of animals such as cows and marine life. More recently, these organisms have been found to also inhabit less extreme environments, such as in the plankton of the open sea1.
Bacteria represent a large group of prokaryotic organisms that are thought to be one of the earliest life forms. Although bacteria are not always thought of in a positive manner since they have been the cause of many diseases, they do have many applications. For example, some bacteria are capable of producing antibiotics; they can live in symbiosis with other eukaryotic organisms; and are used in the production of dairy products. Some characteristics of bacteria are that they are extremely small in size and can reproduce rapidly.
Archaea and bacteria are both very unique prokaryotes which are rather different from each other despite what was once believed. Further research in this area of biology is necessary to study both of these organisms and uncover the true lineages of the Archaean domain of life.
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