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Chromosomal reciprocal translocation of the 4th and 20th chromosome. In genetics, chromosome translocation is a phenomenon that results in unusual rearrangement of chromosomes. This includes balanced and unbalanced translocation, with two main types: reciprocal, and Robertsonian translocation.
Balancer chromosomes are named for the chromosome they serve to stabilize and for the phenotypic or genetic marker the balancer carries. [9] The naming of balancer chromosomes in D. melanogaster has been standardized as follows: the first letter of the chromosome's name represents the number of the chromosome it stabilizes.
A Robertsonian translocation in balanced form results in no excess or deficit of genetic material and causes no health difficulties. In unbalanced forms, Robertsonian translocations cause chromosomal deletions or addition and result in syndromes of multiple malformations, including trisomy 13 (Patau syndrome) and trisomy 21 (Down syndrome). The ...
The balanced translocation figure shows a 14/21 translocation between the long arms of chromosomes 14 and 21, where the other chromosomes are not shown. The individual has two copies of everything on chromosome 14, and two copies of all of the material on the long arm of chromosome 21 (21q). The derivative chromosome 21, which contains only ...
Here fragments accumulate, permitting researchers to analyse the snails taken. The thrushes hunt by sight, and capture selectively those forms which match the habitat least well. Snail colonies are found in woodland, hedgerows and grassland, and the predation determines the proportion of phenotypes (morphs) found in each colony.
This is a reciprocal translocation, creating an elongated chromosome 9 (termed a derivative chromosome, or der 9), and a truncated chromosome 22 (the Philadelphia chromosome, 22q-). [5] [6] In agreement with the International System for Human Cytogenetic Nomenclature (ISCN), this chromosomal translocation is designated as t(9;22)(q34;q11).
Sickle-cell anaemia is found mostly in tropical populations in Africa and India.An individual homozygous for the recessive sickle hemoglobin, HgbS, has a short expectancy of life, whereas the life expectancy of the standard hemoglobin (HgbA) homozygote as well as heterozygote is normal (though heterozygote individuals will suffer periodic problems).
Possessing chromosomes of varying shapes is generally the result of a chromosomal translocation or chromosomal inversion. In a translocation, genetic material is transferred from one chromosome to another, either symmetrically or asymmetrically (a Robertsonian translocation). In an inversion, a segment of a chromosome is flipped end-for-end.