segregation

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segregation

 [seg″rĕ-ga´shun]
the separation of allelic genes during meiosis as homologous chromosomes begin to migrate toward opposite poles of the cell, so that eventually the members of each pair of allelic genes go to separate gametes.

seg·re·ga·tion

(seg'rĕ-gā'shŭn),
1. Removal of certain parts from a mass, for example, those with infectious diseases.
2. Separation of contrasting characters in the offspring of heterozygotes.
3. Separation of the paired state of genes, which occurs at the reduction division of meiosis; only one member of each somatic gene pair is normally included in each sperm or oocyte; for example, an individual heterozygous for a gene pair, Aa, will form gametes half containing gene A and half containing gene a.
4. Progressive restriction of potencies in the zygote to the following embryo.
[L. segrego, pp. -atus, to set apart from the flock, separate]

segregation

(sĕg′rĭ-gā′shən)
n.
1. The act or process of segregating or the condition of being segregated.
2. Genetics The separation of paired alleles or homologous chromosomes, especially during meiosis, so that the members of each pair appear in different gametes.

seg·re·ga·tion

(seg'rĕ-gā'shŭn)
1. Removal of certain parts from a mass (e.g., those with infectious diseases).
2. Separation of contrasting characters in the offspring of heterozygotes.
3. Separation of the paired state of genes, which occurs at the reduction division of meiosis; only one member of each somatic gene pair is normally included in each sperm or ovum.
4. Progressive restriction of potencies in the zygote to the following embryo.
[L. segrego, pp. -atus, to set apart from the flock, separate]

segregation

  1. the separation of HOMOLOGOUS CHROMOSOMES during anaphase 1 of MEIOSIS, to produce gametes containing only one allele of each gene. Such an occurrence is the physical mechanism underlying the first law of MENDELIAN GENETICS and is particularly important when the two separated alleles are different.
  2. an ability of bacterial REPLICONS to be partitioned accurately and evenly between daughter cells during CELL DIVISION. See par LOCUS.
References in periodicals archive ?
The segregational load could also be partly reduced during population bottlenecks, because genetic drift in small, inbreeding populations can result in the fixation of alleles and permanent loss of heterozygote advantage.
To obtain the expected segregational load during phase 2, we note that [mu]K mutations enter the population each generation.
The segregational irregularities may be indicative of selection for the fission morphology resulting perhaps from cytomechanical constraints (White 1969, 1975).
Consequences of Robertsonian heterozygosity: segregational impairment of fertility versus male-limited sterility.
where [Mathematical Expression Omitted], the segregational load for the locus, the reduction of population mean fitness from that of a population consisting solely of the optimal genotype.
Genetic inertia imposed by segregational load and inbreeding associated with the establishment of newly arisen translocations and inversions (O'Brien and Nash 1982)
Selection will act on the entire composite genotype of an asexual, whereas with sexual organisms, recombination will break up any favorable broadly adapted gene complexes (segregational and recombinational loads; Crow 1988).
However, the relative contribution of dominance, overdominance and epistasis to segregational load in Mimulus, critical to the coevolution of inbreeding depression and outcrossing rates (Charlesworth and Charlesworth, 1987, 1990; Charlesworth et al., 1990), remains unknown.