Mutations are called spontaneous changes in the DNA structure of living organisms, leading to the occurrence 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 that exist in the science. It is also worth paying attention to the impact of changes in the genotype on nature.
What is a mutation?
Scientists say that mutations have always existed and are present in the organisms of absolutely all living beings on the planet, moreover, up to several hundred of them can be observed in one organism. Their manifestation and severity depend on what causes they were provoked and which genetic chain suffered.
Causes of mutations
The causes of mutations can be very diverse, and they can arise not only naturally, but also artificially, in the laboratory. Genetic scientists identify the following factors for the occurrence of changes:
1) radiation (ionizing and X-ray) - when radioactive rays pass through the body, they changecharges of electrons of atoms, which leads to disruption of the normal functioning of chemical-biological and physico-chemical processes;
2) an increase in body temperature can also lead to changes due to exceeding the body's endurance threshold;
3) DNA cell division may experience delays and sometimes overgrowth;
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
There are more than 30 changes in the genotypes and gene pools of living organisms caused by mutations in the world, and they are not always expressed in external or internal deformities, many of them are quite harmless and do not cause discomfort. To find the answer to the question: "What is a mutation?" - you can also refer to the classification of mutogens, which are grouped depending on the causes that cause them.
1. According to the typology of changed cells, somatic and generative mutations are distinguished. The first is observed in the cells of mammalian living organisms, is transmitted only by inheritance. As a rule, it is formed during the development of the embryo in the womb (for example, different eye colors, etc.). The second is more often manifested in plants and invertebrates, caused by unfavorable external environmental factors (growth of fungi on a tree, etc.).
2. According to the location of the mutated cells, nuclear mutations are distinguished, which directly affect DNA (they are not amenable totreatment), and cytoplasmic - relate to 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 that provoked the appearance of changes, there are natural (obvious) mutations that occur suddenly and for no reason, and artificial (induced) - these are failures in the normal functioning of chemical and physical processes.
4. Depending on the severity of 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 construction during the formation of new DNA chains (phenylketonuria).
Meaning of mutations
In most cases, they harm the entire body, as they interfere with its normal growth and development, and sometimes lead to death. Beneficial mutations never occur, even if they grant superpowers. They become a prerequisite for the active action of natural selection and influence the selection of living organisms, leading to the emergence of new species or degeneration. Thus, answering the question: "What is a mutation?" - it is worth noting that these are the slightest changes in the DNA structure that disrupt the development and vital activity of the whole organism.
