We explain to you what bacteria are, the types that exist and how is their structure. In addition, some examples and their differences with the virus.
What are the bacteria?
It is called a domain of prokaryotic microorganisms (devoid of a cell nucleus) of various possible shapes and sizes, which together with the archaea, constitute the most primitive living beings and m It is abundant on planet Earth, adapted to virtually all conditions and habitats, including parasitic. Some may even subsist in hostile conditions, such as outer space.
The bacteria are immediate descendants of the first unicellular life forms on the planet, arising under conditions very different from the current ones about 4, 000 million years ago. It is unknown whether these beings were more similar to archaea or bacteria, but it is known that they are their common ancestor.
However, bacteria have been implicated, perhaps due to their abundance, in most cellular evolutionary leaps, such as the origin of mitochondria (in eukaryotic cells) or chloroplasts (in plant cells), through processes of endosymbiosis.
Likewise, these living beings have relations with practically all life forms of the planet, either of commensalism (such as bacteria that proliferate on the skin), mutualism (such as those that collaborate with decomposition). n of food in the intestine) or parasitism (as the cause of infections and diseases). To combat the latter, the human being created antibiotics.
On the other hand, bacterial life is essential in the processes of decomposition of organic matter, necessary for the recycling of elements such as carbon or nitrogen, and constitute the floor of the chains microscopic traffic in various environments.
The bacteria reproduce with speed and by asexual procedures, which consist of the replication of the progenitor cell in two exactly equal to it (mitosis or binary physics). that, in an auspicious environment, a bacterium is divided in two in just 15-20 or 20-30 minutes, depending on the species.
See also: Autotroph.
Types of bacteria
Bacteria are studied by bacteriology, a branch of microbiology. This discipline has classified them according to various criteria, such as their form or their response to staining. In that sense, we can talk about:
- Bacteria according to their form :
- Bacilli Elongated shapes, such as microscopic bars.
- Coconuts With spherical or round shape.
- Vibrios Corkscrew or corkscrew.
- Spirils Shaped propeller or spiral.
- Bacteria according to their response to tincture :
- Gram positive They acquire a violet or clearly violet color when the dye is used.
- Gram negatives They take a clearly red color when dye is used.
There are other classifications, which take into account the habitat, its cellular metabolism or its biochemical components.
The unicellular bacterial structure is usually quite simple, with no cell nucleus and almost no defined organelles, but with a nucleoid (irregular region where the circular DNA of prokaryotes is found), a peptidoglycan cell wall that lines the cell outside the membrane plasma and frequently pili or flagella to move (in case they are mobile).
Scattered in the bacterial cytoplasm there are usually plasmids (small non-chromosomal DNA molecules), vacuoles (reservoirs of reserve substances) and ribosomes (for protein synthesis). Some bacteria have prokaryotic compartments, primitive organelles surrounded by membranes, intended for specific biochemical work within the cell, depending on their metabolism.
Examples of bacteria
Some of the best known bacteria are:
- Escherichia coli A gram-negative bacterium common in the gastrointestinal tracts of humans and other warm-blooded animals, capable at certain times of causing an infection.
- Neisseria gonorrhoeae . Gonococcus that causes gonorrhea, a sexually transmitted infection in humans.
- Bacillus anthracis . Immobile and positive bacterial bacteria that produce recognizable black lesions on the skin (carbuncles).
- Sorangium cellulosum . Myxobacteria gram negative extremely common in soils and harmless metabolism.
- Clostridium botulinum . The causative agent of botulism, by means of a `` neurotoxin '' that these bacteria secrete, whose growth in canned food (the canned cans and that release gas when opened are a clear symptom) and other food preserves is known.
Differences between viruses and bacteria
Viruses and bacteria are extremely different, even though they are the most known and frequent infectious forms for humans.
The main difference has to do with its structure and size : while the bacteria are single-celled organisms whose size ranges between 0.5 and 5 micrometers in length, the viruses are cellular beings. Very simple and elementary, unable to reproduce if it is not infecting other cells that act as a factory for viral replicas, after being inoculated with viral DNA invader.
Consider that viruses do not even know if they are really alive, from the primitive nature of their existence, that it is not much more than a simple molecule of DNA or RNA wrapped in a layer of proteins. For this reason antibiotics have no effect on viruses, but on bacteria; while antivirals or retrovirals are exclusively used to fight virus infections.
More in: Virus.