Bacterial organisms have long mastered all known habitats. They are in the air, in water, live in other organisms. But most of them are in the upper layers of the soil. The number of these organisms depends not only on the structural features. It increases many times due to its great ability to reproduce. How bacteria are propagated will be summarized in the article.
What are bacteria?
These organisms are unicellular, rarely colonial organisms. They are arranged quite primitively. The surface apparatus is represented by a membrane and mucous capsule, and the cytoplasm is devoid of mitochondria and plastids. Many cells have a flagellum with which the bacterium can move.
Genetic material
Bacteria are prokaryotes. This means that their cells lack a nucleus. But genetic material is still present in them. Accumulations of DNA molecules are located in a specific part of the cytoplasm and are called a nucleoid. In other words, we can say that prokaryotes have a core without a shell. Therefore, they cannot carry out complex biochemical processes. However, this does not affect their ability to reproduce.
How are bacteria propagated?
Bacteria multiply by cell division. This is the main and fastest way. Two daughter cells are formed from one mother cell in half an hour. And after the same period of time, two cells again form from two daughter cells. This explains the large number of bacteria in nature.
Under adverse conditions, bacteria can form spores - asexual reproduction cells . Occasionally, bacterial cells are budded - they form small protrusions that grow, turn into adults and split off from the mother.
How bacteria are propagated can also be examined using conjugation as an example. This is a form of the sexual process. It consists in the exchange of hereditary information between cells. Before starting, there is a doubling of the ring DNA molecule. Further, a cytoplasmic bridge is formed between the cells, along which the hereditary information of one cell moves to another. There is an exchange of DNA. As a result, the body acquires new signs that are most often useful to it. For example, bacteria become resistant to adverse environmental factors, viruses or antibiotics.
Nodule bacteria live and multiply on the roots of legumes and cereal plants. Introducing into the root system through the affected areas or root hairs, they grow and form protrusions - nodules. A favorable environment for metabolism is created inside them. The root gives bacteria organic matter, and bacteria - nitrogen, which is so necessary for the growth and development of plants.
Cell division in two
How bacteria are propagated depends on their type and habitat. But all bacterial organisms are able to divide in two. This process occurs in several stages and is called binary division.
Before starting the division, the ring DNA molecule doubles. In other words, replication occurs. The nucleotide divides; daughter DNAs diverge. Growing into the cytoplasm, the cell membrane is located between the DNA molecules. It is she who divides the cell and its contents in half.
72 bacterial generations are born per day from one cell. If all of these bacteria remained viable, their biomass would be about 5 tons. In nature, of course, this does not happen and most bacteria die.
Vegetative propagation
The structure also determines how bacteria multiply.
Colonial species and cyanobacteria (blue-green algae) are capable of vegetative propagation. In this way, plants often reproduce. It consists in the separation of the multicellular part from the whole organism.
The filamentous species of cyanobacteria form specialized cells called heterocysts. Vegetative propagation consists in breaking the filaments, the border of which passes at the locations of the heterocysts.
Cocci spherical bacteria can connect in chains, clusters or other formations. Separating from each other, they also multiply.
Spore formation
Bacteria multiply by spores that form when adverse conditions occur. Spore formation is not only a method of reproduction. A special environment is created inside the spores, the water content is reduced, and vital processes are suspended. In this state, spores are not afraid of high temperatures, or ionizing radiation, or exposure to chemicals. When favorable conditions occur again, young bacterial organisms emerge from the spores. Thus, spore formation is an additional opportunity to maintain cell viability under unsuitable conditions. There are cases when bacterial spores remained viable for tens or even hundreds of years.
Encystation
Another way to protect against adverse conditions and the method of reproduction is the formation of cysts. They are vesicles with thick shells. Bacteria can be in a state of cyst for a long time. However, they do not die from temperatures of more than 200 degrees. With the onset of normal conditions, the bacterium leaves the shell and begins the usual binary division.
In what way bacteria reproduce, environmental conditions rather solve it. When there is a lack of nutrients and moisture, an excess oxygen content is observed, the air has too high or low temperature, bacteria use the processes of encystation or spore formation. In comfortable conditions, they divide or reproduce vegetatively. It is this diversity of breeding methods that bacteria are capable of that determines their number in nature. If the process of division of one cell of the bacterium did not stop within 10 days, they could cover the entire surface of the globe.