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Chromosome segregation is the process in eukaryotes by which two sister chromatids formed as a consequence of DNA replication, or paired homologous chromosomes, separate from each other and migrate to opposite poles of the nucleus. This segregation process occurs during both mitosis and meiosis. Chromosome segregation also occurs in prokaryotes ...
Segregating sites are positions which show differences (polymorphisms) between related genes in a sequence alignment (are not conserved). [1] Segregating sites include conservative, semi-conservative and non-conservative mutations.
The segregation distorter set is composed by the allele Killer (in the Killer locus) and the allele Resistant (in the Target locus), while its rival set is composed by the alleles Non-killer and Non-resistant. So, the segregation distorter set produces a toxin to which it is itself resistant, while its rival is not.
Meiotic recombination allows a more independent segregation between the two alleles that occupy the positions of single genes, as recombination shuffles the allele content between homologous chromosomes. [citation needed] Recombination results in a new arrangement of maternal and paternal alleles on the same chromosome.
Definition Law of dominance and uniformity Some alleles are dominant while others are recessive; an organism with at least one dominant allele will display the effect of the dominant allele. [27] Law of segregation During gamete formation, the alleles for each gene segregate from each other so that each gamete carries only one allele for each gene.
If chromosome segregation happens correctly, each daughter cell receives a complete set of chromatids, and for this to happen each sister chromatid has to anchor (through the corresponding kinetochore) to MTs generated in opposed poles of the mitotic spindle. This configuration is termed amphitelic or bi-orientation.
When the segregation is not normal, it is called nondisjunction. This results in the production of gametes which have either too many or too few of a particular chromosome, and is a common mechanism for trisomy or monosomy. Nondisjunction can occur in the meiosis I or meiosis II, phases of cellular reproduction, or during mitosis.
Niche segregation: The random selection of niches in largely empty niche space will often automatically lead to segregation (this mechanism is of particular importance in the second paradigm). Niches are segregated due to interspecific competition (this mechanism is of particular importance in the first paradigm).