Polymorphism Chromosomal

Chromosome polymorphism

Chromosome polymorphism is the simultaneous presence in a population of two or more morphological variants of chromosomes, and the prevalence of the rarest variant exceeds the level of spontaneous occurrence of repeated chromosomal mutations.

Chromosome polymorphism occurs as a result of chromosomal rearrangements - inversions, translocations, deletions and duplications. These changes in the structure of chromosomes do not lead to significant disturbances in the vital functions of the organism, and therefore become fixed in the population.

Chromosomal polymorphism is widespread among wild species of animals, plants and fungi. In humans, polymorphic variants of some chromosomes have also been described. For example, polymorphism in the length of the arms of chromosome 1, inversions in chromosome 9, etc.

Chromosomal polymorphism plays an important role in the evolution of species because it creates increased diversity of genetic material in populations. In addition, different chromosome morphs may have different fitness under certain environmental conditions.

In genetics, chromosomal polymorphism is the phenomenon of the simultaneous presence in a population of two or more morphological variants of chromosomes - this can be ** heterochromosomy** and haploidy or **polyclonality**. Complete studies of chromosomal polymorphism are carried out thanks to haplotypes of 72 human chromosomes.

Before the development of shotgun genome sequencing techniques, determining the constitutive number of chromosomes was a difficult task at different levels of evolution - from gene sequences and transcriptional pathways to chromosome interaction interfaces. The use of haplotyping makes it possible to identify gene modifications and hereditary diseases associated with altered versions of the chromosomal composition in genes. Thanks to shotgun sequencing, new methods are being developed to identify chromosomal polymorphisms and associate clinical syndromes with each specific gene associated with them.

The term chromoedra is used to describe the structure of chromosomes in cytology and animal genetics to classify their subunits and characteristics of chromosomes within a group of chromosomes of the same type. Heterochromicity is the presence in organisms of two identical sets of chromosomes with different genetic material in each pair. Haploids are organisms with half nuclei that have only one set of chromosomes instead of the pair in diploids. Also, the term heterologancy is a variation of dystrophy.

In addition, chromosome homology is the similarity between pairs or multiple sequences on the same chromosome. In addition to 23 chromosomes, the DNA in prophase of the nucleus contains 9 pairs of X and Y chromosomes (the so-called “extra”), which work like normal X-chromosomal chromosomes for the recessive male set. The male set of Y chromosomes contains a complete set of X chromosomes without a second copy and secondary structures that determine sex. In population genetics, the gene in question is called YD - Y-chromosome-specific gene. Almost all cells contain two paralog copies of both X and Y (that is, "XXXY" and "XYXY").