The term "mutation" goes back to the Latin word"mutatio", which literally means - change or change. Mutational variability refers to persistent and obvious changes in genetic material that are derived from hereditary traits. This is the first link in the chain of formation of hereditary diseases and pathogenesis. This phenomenon began to be actively studied only in the second half of the 20th century, and now it is increasingly possible to hear that mutational variability should be studied, since knowledge and understanding of this mechanism becomes the key to overcoming the problems of mankind.
There are several types of mutations in cells.Their classification depends on the variety of the cells themselves. Generative mutations occur in the sex cells, and there are also gametic cells. Any changes are inherited and often found in the cells of offspring, from generation to generation a number of deviations are transmitted, which eventually become the cause of diseases.
Somatic mutations refer to non-sexualcells. Their peculiarity is that they manifest only in that individual who has appeared. Those. changes are not inherited by other cells, but only when divided in one organism. Somatic mutational variability manifests itself more noticeably when it begins in the early stages. If the mutation happens at the first stages of the fragmentation of the zygote, then there will be more cell lines with different genotypes. Accordingly, more cells will carry a mutation, such organisms are called mosaic.
Levels of hereditary structures
Mutational variability is manifested inhereditary structures, differing in different levels of organization. Mutations can occur on the gene, chromosomal and genomic levels. Depending on this, the types of mutational variability also change.
Генные изменения затрагивают структуру ДНК, в as a result, it changes at the molecular level. In some cases, such changes do not in any way affect the viability of the protein, i.e. functions do not change in any way. But in other cases defective formations can occur, which already stops the protein's ability to perform its function.
Mutations at the chromosome level already carry moreserious threat because they affect the formation of chromosomal diseases. The result of such variability are changes in the structure of chromosomes, and here several genes are already involved at once. Because of this, the normal diploid set may change, which in turn can generally affect DNA.
Genomic mutations as well as chromosomal mutations cancause the formation of a chromosomal disease. Examples of mutational variability at this level are aneuploidy and polyploidy. This is an increase or decrease in the number of chromosomes that are most often lethal for a person.
To genomic mutations is trisomy,meaning the presence of three homologous chromosomes in a karyotype (an increase in the number). Such a deviation leads to the formation of Edwards syndrome and Down syndrome. Monosomy means the presence of only one of the two homologous chromosomes (a decrease in the number), which virtually excludes the normal development of the embryo.
The reason for the occurrence of such phenomenabecome violations at different stages of development of the sex cells. This occurs as a result of an anaphase lag - the homologous chromosomes move to the poles in cell division, and one of them may lag. There is also the notion of "non-divergence", when the chromosomes could not separate at the stage of mitosis or meiosis. The result is a manifestation of violations of varying degrees of severity. The study of this phenomenon will help to unravel the mechanisms and, probably, will make it possible to predict and influence these processes.
