Mutational variability and types of mutations

The term "mutation" goes back to the Latin word "mutatio", which literally means - change or change. Mutational variability refers to the 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 was 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 is becoming 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-sex cells. Their peculiarity is that they appear only in the 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 occurs at the first stages of the fragmentation of the zygote, then more cell lines will appear with different genotypes. Accordingly, more cells will carry a mutation, such organisms are called mosaic.

Levels of hereditary structures

Mutational variability manifests itself in hereditary 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.

Genetic changes affect the structure of DNA, as a result of which 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. But in other cases defective formations can occur, which already stops the protein's ability to perform its function.

Mutations at the chromosomal level already carry a more serious threat, because they affect the formation of chromosomal diseases. The result of such variability is the changes in the structure of chromosomes, and several genes are involved in this process. Because of this, the usual diploid set can change, which in turn can generally affect DNA as well.

Genomic mutations as well as chromosomal mutations can cause 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.

Genomic mutations include trisomy, which means 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 practically excludes the normal development of the embryo.

The cause of these phenomena are disorders 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 during cell division , and one of them may lag behind. 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.