HealthMedicine

What is a mutation?

Mutations are spontaneous changes in the structure of DNA of living organisms, leading to the emergence of all kinds of abnormalities in growth and development. So, let's consider what a mutation is, the reasons for its occurrence and the classifications existing in science. It is also worth paying attention to the impact of genotype changes on nature.

What is a mutation?

Scientists say that mutations have always existed and are present in the organisms of absolutely all living things on the planet, moreover, they can be observed up to several hundred in one organism. The manifestation of them and the degree of expression depend on the reasons they were provoked and which genetic chain suffered.

Causes of mutations

Causes of mutations can be very diverse, and they can arise not only naturally, but also artificially, in the laboratory. Genetic scientists distinguish the following factors for the occurrence of changes:

1) radiation (ionizing and x-ray) - when radioactive rays pass through the body, the charges of the electrons of atoms change, which leads to a disruption of the normal functioning of the chemical-biological and physicochemical processes;

2) an increase in body temperature can also lead to the appearance of changes due to exceeding the threshold of endurance of the organism;

3) delays in the division of DNA cells, and sometimes excessive proliferation;

4) "breakage" of DNA cells, after which, even in case of restoration, it is impossible to return the atom to its original state, which leads to inevitable changes.

Classification of mutations

Over 30 changes in genotypes and gene pools of living organisms caused by mutations are being read in the world, and they are not always expressed in external or internal ugliness, many of them are quite harmless and do not cause discomfort. To find the answer to the question: "What is a mutation?" - you can refer to the classification of mutogens, which are grouped according to the causes that cause them.

1. By the typology of the changed cells, a somatic and generative mutation is distinguished. The first is observed in mammalian cells of living organisms, it is transmitted only by inheritance. As a rule, it is formed even during the development of the embryo in the womb (for example, a different color of the eyes , etc.). The second is more often manifested in plants and invertebrates, is caused by unfavorable external factors of the environment (growth of fungi on the tree, etc.).

2. At the location of the mutated cells, nuclear mutations that directly affect DNA (do not respond to treatment) are distinguished, and cytoplasmic ones concern changes in all cells and fluids that interact with the nucleus (curable or amenable to elimination, such mutations are also called atavisms).

3. Depending on the reasons provoking the appearance of changes, natural (obvious) mutations that arise suddenly and without cause are distinguished, and artificial (induced) mutations are malfunctions in the normal functioning of chemical and physical processes.

4. Depending on the severity, the mutations are divided into:

1) genomic - changes in the number of sets of chromosomes (Down's disease) ;

2) gene mutations - changes in the sequence of nucleotide formation in the formation of new DNA chains (phenylketonuria).

The value of mutations

In most cases, they harm the entire body, because they interfere with its normal growth and development, and sometimes lead to death. Useful mutations never occur, even if they are endowed with supernormal abilities. They become a prerequisite for the active action of natural selection and affect the selection of living organisms, leading to the emergence of new species or degeneration. Thus, answering the question: "What is a mutation?" - it should be noted that these are the slightest changes in the structure of DNA, which disrupt the development and vital activity of the whole organism.

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