term "mutation" comes from the Latin word "mutatio", which literally means - change or change.Mutational variability represents a stable and distinct change in the genetic material that is displayed in the hereditary characteristics.This is the first link in a chain formation and pathogenesis of hereditary diseases.This phenomenon was actively studied only during the second half of the 20th century, and now more and more often you can hear that the 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 germ cells, there are also germline cells.Any changes are inherited and are often found in the cells of the offspring from generation to generation is passed to a number of abnormalities, which eventually become a cause of disease.
Somatic mutations are asexual cells.Their peculiarity is that they appear only to the individual who has appeared.Iechanges are not inherited to other cells, but only at the division in one body.Somatic mutational variability is more pronounced when it starts early.If a mutation occurs in the early stages of crushing zygote, there is a greater cell lines different from each other genotypes.Accordingly, the longer the cells will carry the mutation, such organisms are called mosaic.
levels of genetic structures
mutational variability is manifested in the genetic structures differ different levels of the organization.Mutations can occur at the gene, chromosome and genome level.Depending on this change and the types of mutation.
gene changes affect the structure of DNA, causing it changes at the molecular level.Such changes in some cases do not affect the viability of the protein, i.e.function does not change.But in other cases, may be defective education that has the ability to terminate the protein to perform its function.
chromosomal mutations are already a serious threat, because they affect the formation of chromosomal diseases.The result of this change, are changes in the structure of chromosomes and are already involved several genes.Because this may vary normal diploid, which in turn may influence the whole DNA.
genomic mutations as well as chromosomal may cause the formation of chromosomal disease.Examples of mutation at this level - aneuploidy and polyploidy.This increase or decrease in the number of chromosomes that human are often lethal.
Gene mutations is trisomy, meaning the presence of three homologous chromosomes in the karyotype (increasing the number).This deviation leads to the formation of Edwards syndrome and Down syndrome.Monosomy means that only one of the two homologous chromosomes (reduced amount), which virtually eliminates the normal development of the embryo.
cause of such phenomena are violations at different stages of development of germ cells.This happens as a result of anaphase lag - homologous chromosomes during cell division are moving toward the poles, and one of them could keep up.There is also the concept of "non-disjunction", when the chromosomes could not be divided into stages of mitosis or meiosis.The result is a manifestation of disorders of varying severity.The study of this phenomenon will help to unravel the mechanisms and probably will make it possible to predict and influence these processes.
