Bacteria belong to the realm of moneras. These are tiny unicellular organisms, that is, they are formed by a single cell, they do not contain the hereditary material enclosed in a nucleus, like other cells; nor do they possess the structures that are common in other cells; for this reason it is considered that moneras or bacteria, have little relation with the other kingdoms.
Bacteria, like any other organism, are classified into two categories, according to the way they get their energy, and in this we refer to the terms: Autotrophs and Heterotrophs.
Autotroph organisms are those that have the ability to obtain energy by manufacturing their own food. While organisms that can not produce their food are called Heterotrophs. To understand these two words, let's see their meanings below: Auto- is a prefix that means "by itself" and the root -trofo means "food" and the second prefix hetero-means "other". Heterotrophic organisms can feed on autotrophs or other heterotrophs, but all ultimately depend on autotrophic organisms for their feeding.
Before the term "bacterium" was used to refer to certain types of moneras, others of them were known as blue-green algae, but now they are called cyanobacteria or blue-green bacteria; Nowadays all moneras are considered bacteria, so that both terms are used interchangeably. Since bacteria are a better known term than moneras, from now on we will use the word bacteria to continue referring to these important organisms.
Many scientists have claimed that bacteria were the first life forms on Earth, which appeared about 3,500 million years ago, being the only living beings for 2 billion years; bacteria are the most numerous organisms on Earth, scientists calculate that in an ounce of soil there are an average of 2.500 million bacteria.
The bacteria can have different shapes and sizes, many of them can be seen in the microscope with elongated capsule-shaped, spherical, like a marble, curled like springs, round or have no shape. In addition, the range of colors of the bacteria ranges from red and yellow to blue and violet. Some of them live as separate cells and others in groups of cells linked together.
The cell wall is a rigid and rigid structure that surrounds, holds, shapes and protects the cell; almost all bacteria have a cell wall; They also have a protective layer, this layer is called capsule. Now, how does the capsule protect the bacteria? The cell wall is internally covered by the cell membrane, which will control substances entering and leaving the cell, inside this membrane is the cytoplasm, which is a gelatinous mixture of substances that forms almost the entire cell .
Unlike almost all cells, the hereditary material of the bacteria is not enclosed in the nucleus, since the moneras or bacteria do not have any membrane that separates the hereditary material from the rest of the cell. Many bacteria can not move on their own, move from one place to another in air and water currents, in clothing and other objects. While there are others with structures that allow them to move in liquid media, called flagella. Flagella are species of long, thin whips that propel the bacteria.
As we pointed out earlier, many bacteria are heterotrophic, we said at the beginning that this kind of bacteria is not capable of making its own food, therefore it has to eat, usually other organisms, to obtain energy. Some bacteria feed on living organisms, acting as parasites. This type of bacteria causes infections in humans, animals and plants. Other bacteria feed on dead beings, decomposing these organisms until they become simpler substances. In this process, materials that will serve as nutrients are returned to the soil. Other bacteria are autotrophic, as we also said at the beginning, that this type of bacteria are those that make their own food, some of them use the energy of sunlight to make food; the nauseating smell of sulfur from some sludge or decomposing food is due to the action of this type of bacteria.
ome bacteria break down food and make other tasty or useful products, for example a type of bacteria breaks down milk and forms yogurt. In many cases we want to preserve food and for this we use mechanisms to avoid or delay the decomposition of food by heat, drying, salting, refrigerating, or proceeding to smoke them; All these processes prevent or delay the growth of bacteria, for example, milk when heated at certain temperatures for pasteurization, thus eliminating most of the bacteria that damage it. Bacterial growth can also be prevented by heating and then canning vegetables, fruits, meat and fish; but if they do not heat up enough they can grow bacteria inside the can and produce poisonous toxins that generate a gas that inflates the can, for this reason they should not be consumed, because it can cause serious problems for our health.
Bacteria clean the environment
Bacteria are used to clean the environment, some are used to treat sewage, and to decompose waste; some to decompose oil spilled in the sea and others to decompose complex chemicals such as pesticides and plastics.
Certain bacteria produce substances that fight diseases, some of them are processed to obtain chemical products, which destroy or weaken other harmful bacteria in our body, these products are what are called antibiotics. Before continuing, we must ask ourselves this question: How are bacteria transformed into antibiotics? Recently scientists have found a way to modify the hereditary material of bacteria, with these data or information, scientists have been able to make bacteria produce medicines and other useful substances. There are bacteria that produce a wide range of antibiotics, such as certain strains of the genus Streptomyces (Streptomycin, tetracycline, erythromycin) among others.
Tetracycline made with bacteria
Among the human diseases caused by bacteria we have laryngitis, some types of pneumonia, diphtheria, cholera, tetanus, tuberculosis, bubonic plague and Lyme disease. Other bacteria cause mouth problems such as tooth decay and pyorrhea. Some diseases can be avoided with good hygiene and vaccination and others can be treated with antibiotics.
Although the time has not yet come for bacterial plastics, there are other substances that are commercially manufactured by bacteria for different purposes: coloring food, processing paper and cloth, and modifying chemical products, to name a few.
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