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Last updated 6 November 2017 at 04:12 PM
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Bacteria are common prokaryotic organisms. They are the oldest organisms on earth that have existed for several million years.
Biologists count over 2,500 species of bacteria. There are so many of them on Earth that the total mass of microorganisms is greater than the mass of other living organisms. The general characteristics of bacteria reveal a common feature - a cellular structure with an absent nucleus.
- 1 Cell structure
- 2 Types of bacteria
3 The role of bacteria in human life
3.1 Similar articles
All bacteria have genetic material, which is represented by elongated DNA molecules and about 1 mm in size. Each such molecule contains approximately 5 million base pairs.
Cytolemma separates the cell body from the external environment and adverse factors, while performing the function of a eukaritic membrane. Some types of bacteria have lysosomes, which are formed as a result of the protrusion of the cytolemma into the cell body.
Lysosomes have a function that vaguely resembles respiration in its simplest form. The cytoplasm also contains ribosomes, which are necessary for the synthesis of protein and various amino acids. Some cells need to be attached to each other, and for this, special oblong protein protrusions on the cell wall are used.
In addition, the cell wall allows the cell to maintain its shape, especially under the influence of unfavorable external factors. In addition, the mucous membrane located on top of the cell wall is an additional protection of the cell.
The bacterial kingdom has another common characteristic: almost all bacteria do not have chlorovill and their nutrition consists of ready-made organic matter. The bacterial world is diverse - they exist everywhere. These organisms can be found in water, in soil and on its surface, air, outside and inside animals and people.
Bacteria have adapted to any area for their comfortable existence. So, many of them do not need oxygen for life, they are able to survive in a vacuum, during boiling, or at very low temperatures.
Due to the fact that bacteria multiply rapidly, scientists have the opportunity to observe their life cycle, to carry out various experiments on these microorganisms, finding out their capabilities. Relatively recently, it was found that bacteria are able to survive even outside the world.
For example, some organisms are not harmed by the alkali that makes up the surface of Jupiter. These experiments show that bacteria are, in fact, the only living organisms that can survive in the destructive environment of other planets.
Types of bacteria
Prokaryotes can be divided into several types. This characteristic of all bacteria is carried out due to their shape and appearance:
- in the form of a ball;
- in the form of sticks;
- in the form of bunches;
The number of bacteria is constantly growing in hygrometric progression. They reproduce at a high rate, approximately every half hour. As with any other living organisms, external factors actively influence their reproduction: sunlight, extreme cold or high temperatures.
In addition, they also have an endless struggle between species, which is natural selection to identify stronger and more resistant specimens. If conditions are ideal, the bacterial cell grows at a high rate. When she reaches maturity, she begins to share.
Division in prokaryotes is asexual, and comes without the help of a second individual. Before cell division, its genetic material is noticeably increased to provide information to two "newborn" cells.
In nature, the kingdom of all bacteria has a wide variety, the general characteristics of which attribute them to heterotrophic organisms. In short, they cannot form organic substances from inorganic ones, therefore, according to the type of nutrition, these cells are divided into three types:
- parasites, which in the course of their vital activity can release toxins that are harmful to living organisms. For example, many parasitic bacteria are the main cause of many diseases such as tuberculosis or cholera. Diseases caused by the vital activity of such organisms lead to various complications, sometimes even death. In addition, parasitic bacteria are recognized as plant pathogens, and many cases have already been identified when an accidentally brought bacterium to a certain area affected most fruit trees, causing irreparable harm to agriculture;
- symbiotic. They take their name from the symbiosis in which they perform with living plants. Such organisms are most often found on the roots of plants, forming special tubers on them and saturating the plant with nitrogen;
- saprophytes. These bacteria feed on dead organics. They help to decompose various remains, saturating the soil with useful substances.
The role of bacteria in human life
Many microorganisms live in the digestive tract and intestines, helping the body to digest food. Their absence significantly affects human health.
After taking certain medicines, the number of living organisms in the human intestine is markedly reduced, which leads to discomfort and poor health.
Scientists have noticed that many of these organisms are capable of degrading inorganic substances. For example, oil, pesticides or dyes. And it doesn't matter if these substances got into the environment. Thanks to this, the problem of non-degradable food waste, which man has generously enriched nature, is gradually being solved.
Moreover, the short lifespan and rapid reproduction allows bacteria to successfully adapt to changing environments and living conditions. A new enzyme was discovered in many microorganisms, which was formed relatively recently.
With the help of this enzyme, microorganisms can degrade pesticides so quickly that the time of exposure of the latter to pests is sharply limited. Other organisms can be used to extract oil from wells.
In addition, they are an important element in saturating the soil with useful substances. So, during the life of some types of bacteria, humus is formed, which is useful for plants.
Humus is decomposed organic matter that plants actively feed on. Bacteria also circulate certain substances in nature. For example, they decompose organic matter, releasing the active substance in the form of nitrogen.
Nitrogen is absorbed by the roots of plants and stored in their leaves, which, after dying off, re-saturate the bud with nitrogen.
Bacteria are also actively used in industry. With their help, sewage is purified, and many types of antibiotics are produced from their waste products, the most famous of which is penicillin.
The discovery of this medicinal substance made a real breakthrough in the history of medicine and humanity as a whole. Some prokaryotes are also used in the food industry to produce yeast, vinegar, alcohol or lactic acid.
In addition to precipitating milk proteins, lactic acid plays an important role in protecting cucumbers or cabbage during fermentation.