There is a small microrganism, know as Pseudomonas aeruginosa, which is able to infect people with cystic fibrosis. Well, recently it was seen how it is able to eliminate competition of other bacteria through injection of a lethal toxin. In fact, the competition between bacteria is a very cruel fight, of course compared to their nature and size. Not far in time, there was talk of bacteria, especially since he took the headlines of newspapers a particular strain of Escherichia coli that has caused several deaths in Germany and other European countries. But what about of bacteria?
They are unicellular organisms (ie compounds from a single cell) belonging to the world of prokaryotes (the oldest type of cells on the face of our planet), with varying dimensions between 0.2 and 30 microns (that is, up to 1/3 of the diameter of a human hair). Some types of bacteria can adapt to living in extreme environmental conditions (and their are known as archaea), but we can say that each bacterium has optimal conditions for growth and reproduction. There is a subdivision that is often more important for its link with animal and plant population: commensal bacteria (ie, those who live together to a body without causing disease) and pathogens (able to bring diseases). It is therefore essential to recognize a bacterium to another. Usually the most common analysis are those that provide for the recognition under the microscope (identifying typical structures) or staining of the bacterium with chemical reagents (answer to a dye rather than to another is typical for each bacterium). But you can also take advantage of its biochemical characteristics: growth on specific culture media (again, each bacterium has strictly need for specific nutrients) or production of typical enzymes which can help in identification.
But how it's exactly a bacterium? We start from the outside, where we encounter the first cell wall, which has a varying thickness in different bacteria. This is already a first element that allow us identification: some walls are so thick (gram-positive bacteria, from scientist who created this staining method) that some chemical dyes can pass through but then they cannot be washed away with solvents and the cells are stained dark blue; otherwise those which have a thinner wall (gram-negative) are more easily to decolorize and they assume a pink color. Under the cell wall is present the cell membrane, consisting of a particular form of fats, which delimits the inner space of the cell. You can easily imagine the structure of the cell by placing a drop of oil in a glass of water: the cell uses roughly the same principle to refine its internal space from the external environment. Attached to the cell membrane are also many enzymes responsible not only for the life of the cell but also for its "social life", allowing interaction with other bacteria. The internal space is formed from the cytoplasm, a liquid substance in which there are many other proteins with the most disparate functions. Some are for the "life" of the cell, others for movement (forming flagella or cilia, a bit as occurs in the sperm), and still others for the reproduction of the cell (through the division of single one cell into two cell daughters). In bacteria, there is not a nucleus (as in our cells, known as eukaryote, structurally most advanced) and DNA is located in a region that is named nucleoid. Some pieces of circular DNA (plasmids) have a story in itself: while DNA controls normal vital activities of the cell and is passed only to the daughter cells, plasmids contains, for example, resistance to certain antibiotics and they can also be passed between bacteria not related each others.
But it's is not all! Not yet!
They are unicellular organisms (ie compounds from a single cell) belonging to the world of prokaryotes (the oldest type of cells on the face of our planet), with varying dimensions between 0.2 and 30 microns (that is, up to 1/3 of the diameter of a human hair). Some types of bacteria can adapt to living in extreme environmental conditions (and their are known as archaea), but we can say that each bacterium has optimal conditions for growth and reproduction. There is a subdivision that is often more important for its link with animal and plant population: commensal bacteria (ie, those who live together to a body without causing disease) and pathogens (able to bring diseases). It is therefore essential to recognize a bacterium to another. Usually the most common analysis are those that provide for the recognition under the microscope (identifying typical structures) or staining of the bacterium with chemical reagents (answer to a dye rather than to another is typical for each bacterium). But you can also take advantage of its biochemical characteristics: growth on specific culture media (again, each bacterium has strictly need for specific nutrients) or production of typical enzymes which can help in identification.
But how it's exactly a bacterium? We start from the outside, where we encounter the first cell wall, which has a varying thickness in different bacteria. This is already a first element that allow us identification: some walls are so thick (gram-positive bacteria, from scientist who created this staining method) that some chemical dyes can pass through but then they cannot be washed away with solvents and the cells are stained dark blue; otherwise those which have a thinner wall (gram-negative) are more easily to decolorize and they assume a pink color. Under the cell wall is present the cell membrane, consisting of a particular form of fats, which delimits the inner space of the cell. You can easily imagine the structure of the cell by placing a drop of oil in a glass of water: the cell uses roughly the same principle to refine its internal space from the external environment. Attached to the cell membrane are also many enzymes responsible not only for the life of the cell but also for its "social life", allowing interaction with other bacteria. The internal space is formed from the cytoplasm, a liquid substance in which there are many other proteins with the most disparate functions. Some are for the "life" of the cell, others for movement (forming flagella or cilia, a bit as occurs in the sperm), and still others for the reproduction of the cell (through the division of single one cell into two cell daughters). In bacteria, there is not a nucleus (as in our cells, known as eukaryote, structurally most advanced) and DNA is located in a region that is named nucleoid. Some pieces of circular DNA (plasmids) have a story in itself: while DNA controls normal vital activities of the cell and is passed only to the daughter cells, plasmids contains, for example, resistance to certain antibiotics and they can also be passed between bacteria not related each others.
But it's is not all! Not yet!
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