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Thomas Hunt Morgan's illustration of crossing over (1916) A double crossing over. Chromosomal crossover, or crossing over, is the exchange of genetic material during sexual reproduction between two homologous chromosomes' non-sister chromatids that results in recombinant chromosomes.
Following recombination, chromosome segregation occurs as indicated by the stages metaphase I and anaphase I in the meiosis diagram. Different pairs of chromosomes segregate independently of each other, a process termed “independent assortment of non-homologous chromosomes”. This process results in each gamete usually containing a mixture ...
Most recombination occurs naturally and can be classified into two types: (1) interchromosomal recombination, occurring through independent assortment of alleles whose loci are on different but homologous chromosomes (random orientation of pairs of homologous chromosomes in meiosis I); & (2) intrachromosomal recombination, occurring through ...
Meiosis generates gamete genetic diversity in two ways: (1) Law of Independent Assortment. The independent orientation of homologous chromosome pairs along the metaphase plate during metaphase I and orientation of sister chromatids in metaphase II, this is the subsequent separation of homologs and sister chromatids during anaphase I and II, it ...
The physical basis of the independent assortment of chromosomes is the random orientation of each bivalent chromosome along the metaphase plate with respect to the other bivalent chromosomes. Along with crossing over, independent assortment increases genetic diversity by producing novel genetic combinations.
Points of crossing over become visible as chiasma after the synaptonemal complex dissembles and the homologous chromosomes slightly apart from each other. The phenomenon of genetic chiasmata ( chiasmatypie ) was discovered and described in 1909 by Frans Alfons Janssens , a Professor at the University of Leuven in Belgium .
The second, the law of independent assortment, states that "alleles of different genes assort independently of one another during gamete formation". Although his work was published, it lay dormant until it was rediscovered in 1900 by Hugo de Vries and Carl Correns but it was not until 1909 that non-mendelian inheritance was even suggested.
A monohybrid cross is a cross between two organisms with different variations at one genetic locus of interest. [1] [2] The character(s) being studied in a monohybrid cross are governed by two or multiple variations for a single location of a gene.