Drosophila Polytene Chromosomes
TranslocationsTranslocation - a change in position of a chromosomal segment to another region of the same chromosome or to another chromosome
Chromosomal material is also maintained, but in a different arrangement after a translocation. Intrachromosomal translocations involve the movement of a chromosomal segment from one location in the chromosome to another. This is normally non-reciprocal, that is another segment does not exchange places with the first segment. Interchromosomal translocations involve the movement of a chromosomal segment(s) between chromosomes. Reciprocal translocations occur when chromosomal segments are exchanged between two non- homologous chromosomes and is the most typical type of translocation. Non-reciprocal translocations are a one-way transfer of a chromosomal segment to another chromosome.
Translocations have two genetic consequences. First, if a segment is inserted between two genes then the linkage distance between those two genes will increase. Secondly, the genes found on the inserted segment will be nearer the genes in the region in which it was inserted, thus defining new linkage relationships among these genes.
Copyright © 1997. Phillip McClean