Prokaryotic Cells: What They Are And What Are Their Characteristics
Taxonomy and phylogeny, animals are a kingdom of living beings that brings together a large group of organisms. All members of this taxon have a series of characteristics in common: they are eukaryotes (they have a nucleus delimited in the cell), heterotrophs, multicellular, with organization in the form of tissues and organs, extensive capacity for movement and embryonic development with common patterns. .
As you already know, human beings are within this group, since we continue to be bipedal vertebrate animals, despite moving further and further away from natural selection and the biological processes that characterize the rest of living beings. For our part, the human being is made up of 30 million million cells, 84% of them being red blood cells or red blood cells, responsible for transporting oxygen in the blood to all our organs.
With these lines we have described multicellular eukaryotic living beings, that is, invertebrates, fish, birds, reptiles, amphibians and mammals. In any case, we cannot forget that there is a microscopic world that, although it cannot be observed with the naked eye, is one of the most important bases of all ecosystems on Earth. Today we tell you everything about prokaryotic cells and the organizations that present them. Do not miss it.
The prokaryotic cell is defined as the cell body of a unicellular organism without a nucleus (prokaryote), whose genetic material is found in the cytoplasm , grouped in an area called nucleoid. Prokaryotic microorganisms are almost without exception unicellular, and include the taxonomic groups of bacteria and archaea.
Although there are a series of vital differences between the cells of animals, plants and fungi that make up the body of many microorganisms, every cell must present a series of basic “ingredients” to be considered as such. Among them, we find the following:
Except for the compartments typical of prokaryotes, all the points that we have mentioned in this list are essential for a cell to be considered as such. Due to this very specific definition, Viruses would be left out of the group of microorganisms and, therefore, could not be considered living beings to use.
Before continuing with the study of prokaryotes, it is very interesting to pose the following dilemma: are viruses alive? The answer, at least strictly speaking, is no.
The basic unit of life is the cell , and this must present all the components mentioned above. Although a virus has a kind of “membrane” that delimits it from the environment (protein capsid) and genetic information in the form of DNA or RNA, it does not have cytosol, ribosomes or other organelles. Since it does not have ribosomes, it is not capable of synthesizing proteins on its own and, therefore, cannot reproduce autonomously: this is where viruses fail as living beings.
Due to this very primitive mechanism, all viruses are parasites These must enter a host cell, take advantage of its replication mechanism and multiply thanks to its complex machinery. Without the ribosomes and other organelles of their host, viruses would not be able to persist at the evolutionary level.
Other characteristics of prokaryotic cells
As we have said previously, there are some organelles that are exclusive to these cell types. An example of this are phycobilisomes, complexes of water-soluble pigments that serve mainly as light reception antennas in cyanobacteria and red algae. Also Magnetosomes, intracellular magnetite crystals that allow bacteria to organize themselves in the environment, stand out for their interest according to magnetic polarity.
Better known are the flagella, fimbriae and pili, protein appendages of variable hardness, thickness and length that allow microorganisms to move through the environment and interact with each other. Without these structures, many bacteria, protozoa and other microscopic beings would not be able to relate to their environment.
Multicellular animals can “afford” to organize our tissues based on their functionality, and that is why we have legs, sense organs and evolutionarily advanced structures that allow us to develop in the three-dimensional environment. Since microorganisms are unicellular, natural selection must “manage” to accumulate the maximum possible number of adaptations in an extremely limited environment , as is the covering of a cell and its cytosol. The organelles and structures previously mentioned exemplify this.
It may seem that prokaryotes do not play an essential role in ecosystems, as they are invisible to the human eye and, as such, should be relegated to minor conservation work. Nothing could be further from the truth: we show you the importance of prokaryotic cells with a series of very easy to understand data.
It is estimated that On planet Earth there are about 550,000 million tons (550 gigatons or Gt) of carbon , chemical element that represents the amount of biomass (organic matter) available for the existence of living beings. As you can imagine, most of this organic matter is stored in plants, which contribute 450 Gt of carbon, or in other words, 80% of the total.
The consequential thing would be to think that the human being and the rest of the animals would appear in second place, right? Well no. It is shocking to know that the second most contributing living beings are bacteria, since they provide the Earth with 70 gigatons of carbon (15% of the total). Animals, sadly, barely contribute more than 2 Gt of organic matter to ecosystems.
The functionality of prokaryotic cells (bacteria and archaea) is not limited only to the accumulation of biomass. Some are capable of transforming organic matter into inorganic matter (and vice versa), others carry out fermentation processes, are present in the carbon, phosphorus, nitrogen cycles and even synthesize oxygen, among many other things: in short, without bacteria, the life would not be possible.
Anyway, There is no need to go to the jungle to understand the essentiality of prokaryotic microorganisms: just look in the mirror It is estimated that 39 billion bacteria live inside and on the surface of human beings, many of them commensals, some potentially pathogenic and others symbionts, which allow us to conceive of our species as what it is today.
The highest concentration of bacteria in humans is found in the gastrointestinal tract, where they perform a series of invaluable functions. Among them, we can highlight that they “guide” our immune system at birth, allow us to metabolize substances of plant origin that we could not digest on our own and protect us from pathogenic agents, secreting bactericides and occupying with high efficiency the ecological niche that is our internal cavities. Without bacteria, ecosystems would not exist, but neither would our body as we conceive it
Summary
Prokaryotic cells are the “simplest” from an evolutionary point of view, but the organisms that present them (bacteria and archaea) are as important as the most complex living being you can think of, even more so. They are the first to colonize any environment, they establish extremely complex biochemical relationships with the inorganic components of ecosystems and allow the entry, in the long term, of more advanced beings on the evolutionary scale.
If we want you to have an idea of everything discussed so far, it is the following: Prokaryotic cells differ from eukaryotic cells mainly in that the former do not have a nuclear envelope in their cytoplasm , that is, the genetic information is “free” in the form of a nucleoid. Although they are considered simpler than the eukaryotic cell bodies that make up vertebrates and invertebrates, they are just as important as any other organic element present on Earth.
