Karyotype


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karyotype

[′kar·ē·ə‚tīp]
(cell and molecular biology)
The complement of chromosomes characteristic of an individual, species, genus, or other grouping.
An organized array of the chromosomes from a single cell, grouped according to size, centromere position, and banding pattern, if any.

Karyotype

 

chromosome set, the aggregate features of the chromosomes (numaber, size, shape, details of microscopic structure) in the cells of an organism of a given species.

The concept of the karyotype was introduced by the Soviet geneticist G. A. Levitskii in 1924. The karyotype is one of the most important genetic characteristics of a species, since every species has a particular karyotype that is different from that of related species (karyosystematics, a new branch of systematics, is based on this phenomenon). The fixed nature of the karyotype in the cells of a given organism is ensured by mitosis and, within a given species, by meiosis. The karyotype of an organism may change if the gametes are altered by mutation. The karyotype of individual cells sometimes differs from the species karyotype because of chromosomal or genomic somatic mutations. The karyotype of diploid cells consists of two haploid sets (genomes) from each parent; each chromosome of such a set has a homologue from the other set. The karyotype of males may differ from that of females in the shape (sometimes also in number) of the sex chromosomes, in which case they are described separately.

The chromosomes in a karyotype are studied during the metaphase stage of mitosis. The description of a karyotype must be accompanied by a microphotograph or sketch. In systematizing karyotypes, the pairs of homologous chromosomes are arranged (for example) in order of decreasing length, beginning with the longest pair. The pairs of sex chromosomes are put at the end of the series. Pairs of chromosomes of equal length are identified by the position of the centromere (primary constriction), which divides the chromosome into two arms, by the position of the nucleolar organizer (secondary constriction), and by the shape of the satellite. The karyotypes of several thousand species of plants (wild and cultivated) and animals and man have been studied.

REFERENCES

Rukovodstvo po tsitologii, vol. 2. Edited by A. S. Troshin. Moscow-Leningrad, 1966.
Lobashev, M. E. Genetika, 2nd ed. Leningrad, 1967.

IU. F. BOGDANOV

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Milia A et al in 1984 reported the results of a karyotype analysis carried out on 282 patients clinically selected for some suspicion of chromosome abnormalities.
presented the second case with 48,XXY,+mar karyotype determined by conventional cytogenetic analysis.
1--The mother's karyotype shows a balanced non-Robertsonian translocation between chromosome 11 and chromosome 22.
Approximately 20% of all AML and 30% of AML with normal karyotype cases harbor IDH1 or IDH2 mutations (27).
Karyotype composition in three California abalones and their relationship with genome size.
Moreover, two karyotype forms (I and II) corresponding to two species, with different 2n, NF, and NFa number, have been recently recognized in Egypt by Shahin et al.
Stem cells cultured in AlphaSTEM maintain normal karyotype for at least 70 passages.
Therefore, based on the lack of knowledge about karyotype evoluton and genome organizaton of Meliponini, we carried out cytogenetic analyses in 6 species of Frieseomelita using C-banding, base-specifc fuorochrome staining and fuorescence in situ hybridizaton with microsatellite probes to provide a refned analysis of the heterochromatn compositon and variaton among these species.