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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.
Genetic characteristics have alternate forms, each inherited from one of two parents. Today these are called alleles. One allele is dominant over the other. The phenotype reflects the dominant allele. Gametes are created by random segregation. Heterozygotic individuals produce gametes with an equal frequency of the two alleles.
A: Short arm (p arm) B: Centromere C: Long arm (q arm) D: Sister Chromatids. In humans, centromere positions define the chromosomal karyotype, in which each chromosome has two arms, p (the shorter of the two) and q (the longer). The short arm 'p' is reportedly named for the French word "petit" meaning 'small'. [ 1 ]
The Boveri–Sutton chromosome theory (also known as the chromosome theory of inheritance or the Sutton–Boveri theory) is a fundamental unifying theory of genetics which identifies chromosomes as the carriers of genetic material. [1][2][3] It correctly explains the mechanism underlying the laws of Mendelian inheritance by identifying ...
Contents. Genetic recombination. A model of meiotic recombination, initiated by a double-strand break or gap, followed by pairing with an homologous chromosome and strand invasion to initiate the recombinational repair process. Repair of the gap can lead to crossover (CO) or non-crossover (NCO) of the flanking regions.
The normal separation of chromosomes in meiosis I or sister chromatids in meiosis II is termed disjunction. 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.
The process of meiosis I is generally longer than meiosis II because it takes more time for the chromatin to replicate and for the homologous chromosomes to be properly oriented and segregated by the processes of pairing and synapsis in meiosis I. [7] During meiosis, genetic recombination (by random segregation) and crossing over produces ...
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 proportion of segregating sites within a gene is an important statistic in population genetics since it can be ...