People from the very beginning of their existenceengaged in the knowledge of themselves and the world. And often research activity leads to the fact that people intentionally interfere in the usual processes, thereby disrupting the course of events and introducing obvious changes that affect not only the surrounding nature, but also the person.
Mutagenesis is a process of changes in the structure of DNA, as a result of which a mutation of the organism occurs.
There are two types of mutagenesis: artificial (induced) and natural (spontaneous).
In 1899, the Russian scientist Korzhinsky wasgiven the scientific explanation of mutagenesis. In 1900, the geneticist Frieze continued to study the phenomenon, and it was this scientist who gave the current definition of mutagenesis.
These two scientists deduced the following propositions of his theory:
Most often, mutagenesis occurs when mistakes are made when doubling and restoring DNA strands, when there is a violation of the chromosomes to the poles during meiosis.
Generally, in every cell there is a constantrecovery of broken DNA chains. However, if DNA integrity is not restored, all errors in the genetic code will accumulate, which ultimately leads to a mutation process.
It occurs under natural conditions of development, when no mutagens act from the outside.
What could be the reasons for the appearance of this kind of it:
For example, in areas of arctic coldvegetation has a polyploid form. It depends on the fact that during the growing season at abnormally low temperatures a number of genomic mutations are formed in plants.
For a long time, scientists believed thatfactors of natural mutagenesis are cosmic waves and natural radiation. However, in the course of the research it was found that only a small fraction of spontaneous mutagenesis is formed under the action of radiation.
It is established that the cause is local small deviations of the thermal motion of the particles.
Artificial mutagenesis is the process of creating artificial mutations to produce the necessary material.
For example, in plant breeding, scientists applymutagenic factors that transform the original genotype. In the course of this, modified plant species are obtained with new signs and forms that their original species do not have.
Therefore, it can be said that induced mutagenesis in breeding plays an important role in obtaining new varieties.
Its mechanism looks like a violation of the fragment.DNA If it was carried out with inaccuracies, then the formation of mutations is inevitable. If the violation occurred in an unimportant part of the DNA, or vice versa, in a meaningful fragment, then the mutation will appear, but it will not appear once and more.
Mutagens are phenomena that cause mutational changes in the body. By the nature of their origin, they are all divided into physical and chemical.
Physical mutagens include:
The methods of their impact are as follows:
Chemical mutagens are as follows:
The mechanism of chemical mutagens is as follows:
So, we can confidently say that mutagenesis is a phenomenon that can affect the state of the body.
Если мутаген затронет «незначительный» фрагмент DNA, in fact, the organism will not undergo any changes. Mutations will exist in the DNA “memory” and are inherited, and with time they can disappear altogether.
But if mutagenesis factors affect a significantDNA fragment, as a result of which the standard amino acid sequence will be disrupted, this will lead to irreversible changes in the body. And if the mutation is detected in the overwhelming majority of individuals of a particular species, then in the future this will lead to significant changes in the characteristic features of the species.
Since mutagenesis is a violation of the normal integrity of DNA, mutations are capable of harming the body.
The overwhelming number of mutations can reduce the vital activity of organisms and provoke the emergence of serious diseases.
Those effects of mutagenesis that are formed insomatic cells are not transmitted with genetic material to the next generation. But as a result of mitotic division, when new cells form, forming a tissue, tumor consolidations can form.
Mutations that affect germ cells are capable of being passed on to the next generation.
Specific example:a mutation that leads to the shortened wings of one of the representatives of the insect, will later manifest itself in the rest of its species, and if these insects live in a windless area, then it will be difficult for them to move. In this case, it will be a matter of acquired disease or even deformity.
But if strong winds begin to blow in such an area, the original appearance of insects with long wings will suffer inconvenience, and the short-winged, on the contrary, will have advantages.
Thus, it can be said that mutations can generate a new species of organism by changing the genomic structure of an existing species.
