The term monera or monera was introduced by Haeckel in 1986 as a phylum within the Protista kingdom. Later, in 1969, Robert H. Whittaker proposed the classification of life forms in 5 kingdoms of nature: Animalia, Plantae, Protista, Fungi and Monera. This classification has been accepted as accurate until recently, considering the Monera kingdom as one that encompasses microscopic unicellular organisms without a defined nucleus, also known as prokaryotes, differentiating between archaebacteria and eubacteria. However, with the development of new identification techniques and the work of Woese in the 1980s, it was observed that the so-called archaebacteria presented important structural and molecular differences with bacteria and, therefore, had to be considered independently with respect to these, under a new perspective of domains: Archaea and Bacteria.
If you want to know more about Monera kingdom: what is it, characteristics, classification and examplesKeep reading this Green Ecologist article, in which we are going to explain the peculiarities of this kingdom.
In nature there are 5 kingdoms: the Animalia kingdom, the Plantae kingdom, the Fungi kingdom, the Monera kingdom and the Protista kingdom. The Monera kingdom (from the word “moneres” = “simple”) or monera kingdom it is formed by prokaryotic organisms, that is, unicellular beings lacking a defined nucleus and with sizes between 3 and 5 µm, among which are bacteria. The Monera kingdom is made up of the oldest, most widespread and numerous organisms on Earth, present in all types of ecosystems, both aquatic and terrestrial. They are organisms whose form of nutrition can be autotrophic or heterotrophic (parasitic or saprophytic). In these other posts we talk in detail about autotrophic organisms: what they are, characteristics and examples and heterotrophic organisms: what they are, characteristics and examples.
In addition, these beings can be found in isolation or forming colonies, as a consequence of cell division without subsequent separation of the descendant cells.
In addition to those already mentioned, some of the main characteristics of the Monera kingdom are:
In addition to the above characteristics, it should be noted that the components of the kingdom Monera are made up of a series of typical structures that are exposed next.
As mentioned at the beginning of this article, in the past, within the Monera kingdom two types of organisms were differentiated: eubacteria and archaebacteria. However, it was later concluded that the latter had an evolutionary history completely independent of bacteria and were considered as two separate groups: archaea and bacteria. So, this is the classification of the kingdom Monera:
They are the oldest existing prokaryotes on Earth and are characterized by inhabiting environments with extreme conditions (for example, hot springs and saline areas), due to the fact that they have a cell wall with a characteristic structure that allows them to survive such conditions. They share characteristics both with bacteria (such as, for example, their prokaryotic cell structure, their types of metabolism, such as nitrogen fixation or denitrification, etc.) and with eukaryotic cells (for example, they have autotrophic nutrition, they lack peptidoglycans in cell wall and possess RNA polymerases with multiple polypeptides, among other things). They present nucleotide sequences in their unique t-RNA and r-RNA.
The name of eubacteria means "true bacteria", and they have the typical characteristics mentioned above, such as having rigid cell walls composed of peptidoglycans, locomotion with the help of flagella, presence of pili on the cell surface that help in sexual reproduction and also pathogens to attach to a host they are going to invade, and so on.
Known as blue-green algae because they were considered as such for a long time, they are the only prokaryotic organisms capable of oxygenic photosynthetic processes. They are the largest prokaryotic organisms, being able to reach dimensions of up to 60 micrometers. Some, in addition, are capable of fixing nitrogen and have developed specialized cells called heterocysts to be able to combine this process (which cannot take place in the presence of oxygen) with that of oxygenic photosynthesis. As prokaryotic organisms, the presence of gas vacuoles stands out in some types, which favors their buoyancy. The characteristic color of some of these organisms is given by the combination of phycobilin and chlorophyll a, but other species can be green, brown, yellow, black or red due to other pigments such as carotenoids and phycoerythrin. Although most cannot exist in the absence of light, certain species can if there is a sufficient supply of glucose to serve as a source of carbon and energy.
In closing, these are some examples within the monera kingdom:
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