The structure of the bacterial cell: for the curious

Bacteria may seem like simple microorganisms, but do not be deceived by this simplicity. In fact, the structure of the bacterial cell makes it very adaptable to its vital needs. Some bacterial cell formations are unique and explain their unusual biological properties.

Previously, the word "bacteria" meant "any prokaryotes." In our time, more primitive and small forms of life are distinguished - the archaea. They differ from the true bacteria. The latter have properties, for the archaean are uncharacteristic.

Before the discovery of electron microscopes in the 50s of the previous century, the structure of the bacterial cell was a secret for scientists. More precisely, bacteria were understood simply as "some proteins and lipids." The structure of the bacterial cell became an object of study only after the mysterious world of the smallest forms of life was discovered.

There are at least 4 species of bacteria in the form: spherical cocci, filamentous bacteria, bacillus sticks and crimped spirilla rods. The small size of the bacterial cell gives it an evolutionary advantage, because the surface area / volume ratio is quite large, which allows the bacterial cell to successfully adapt to the environment, the metabolic processes proceed faster and more efficiently.

The cytoplasmic membrane delimits the internal contents of the bacterial cell. But much more important is its contribution to maintaining the stability of the internal environment, because because of osmotic pressure, processes can go not in the right direction, but the membrane is opposed to this natural process. A unique feature that is always mentioned when talking about the structure of a bacterial cell is the cell wall, which contains a substance called peptidoglycan. It is porous and transmits many solutions to the membrane. Some bacteria of the cell wall do not have (mycoplasmas), but this is an exception. Therefore, penicillin antibiotics and antibiotics-cephalosporins, which disrupt the synthesis of the cell wall, are effective in combating bacterial infection. They do not affect mammalian cells, because the latter do not need a cell wall. And bacteria without it can not survive - it's their outer skeleton and barrier against dangerous influences.

Depending on the resistance to staining according to the Gram method, bacteria are divided into gram-positive (blue after staining) and gram-negative (pink). In gram-positive bacteria, peptidoglycans contain many polysaccharide structures, while in the gram-negative bacteria, the layer is very thin, and there is an outer shell of phospholipids from the outside.

In bacteria, the nucleus is not isolated by the membrane, all the processes of DNA multiplication, transcription and translation take place right among other organelles. DNA is not laid down with the help of histones, but is in a still mysterious superhelical form. Also in the transfer of genetic material involved plasmids, special formations in the cytoplasm. They do not carry the most important information, but they can give the owner an advantage. They are transmitted when reproducing horizontally. Simply put, who they get when dividing the cells in two - and lucky.

The cell also contains ribosomes, which in all cells of living organisms synthesize a protein. In this respect, bacteria are no exception. The structure of a bacterial cell is also characterized by the fact that most bacteria do not have internal membranes that differentiate different cell compartments. Exception - some phototrophs and bacteria, oxidizing methane.

Bacteria can store carbon in the form of glycogen, sulfur in the form of granules and nitrogen in the form of nitrates. Also, bacteria living in water have gas bubbles that allow them to stick to the surface. Some species have special organelles - carboxysomes (fix carbon dioxide from the atmosphere) and magnetosomes - orient the bacterium in a magnetic field (for what - a riddle).

Unique special protein formations of the bacterium - the pili, thanks to which the bacteria attach to the surfaces. And also interesting flagella, allowing them to move around in space.

The world of bacteria is waiting for inquisitive researchers. And the others now will not confound the task: "Describe the structure of the bacterial cell."