Translocation heterozygote | definition of translocation heterozygote by Medical dictionary
Fig. 305 Translocation heterozygote . Adjacent and alternate disjunction.
Fig. 304 Translocation heterozygote . (a) Normal cell. (b) Reciprocal translocation heterozygote.
translocation heterozygote an individual carrying cells with one normal set of chromosomes and one set in which a reciprocal TRANSLOCATION has occurred between two non-HOMOLOGOUS CHROMOSOMES. See Fig. 304 . Such an event causes pairing problems in prophase 1 of MEIOSIS when the chromatids undergo SYNAPSIS (2). These problems are solved by producing a cross-shaped configuration where all chromosomal segments are correctly paired.
When the chromatids separate they can do so in two ways, ‘adjacent’ or ‘alternate’ disjunction. See Fig. 305 . Adjacent disjunction produces gametes that have duplicated and deficient chromosomal segments, and therefore produces gametes that can cause death in the offspring. Alternate disjunction, produced by a twisting of the cross, results in a mixture of completely normal gametes and ones containing a balanced translocation. These types are both viable and the progeny will all survive. The overall result of a translocation heterozygote is that about half of the progeny survive, a fact that has been used in experiments to control insect populations.
References in periodicals archive
In each generation, selection for translocation heterozygotes
and against disassembled chromosomes MA1 was by C-banding.
After seven backcrosses, the translocation heterozygotes
, which were developed from two separate backcross programs, were self-pollinated.
Selection of the translocation heterozygotes
in backcrosses was by C-banding.
Translocations may have profound effects on recombination through physical suppression of pairing around the breakpoint (Burnham, 1934; Bridges and Brehme, 1944), as well as inviability of duplicate-deficient (Dp-Df) spores arising from interstitial recombination in translocation heterozygotes
After [BC.sub.7] the translocation heterozygotes
were self pollinated and among their progeny, translocation homozygotes and their 2B disomic sibs were isolated and grown.