Fertilisation and genetic recombination::Fertilisation


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Fertilisation and genetic recombination Meiosis results in a random segregation of the genes that each parent contributes. Each parent organism is usually identical save for a fraction of their genes; each gamete is therefore genetically unique. At fertilisation, parental chromosomes combine. In humans, (2²²)² = 17.6x1012 chromosomally different zygotes are possible for the non-sex chromosomes, even assuming no chromosomal crossover. If crossover occurs once, then on average (4²²)² = 309x1024 genetically different zygotes are possible for every couple, not considering that crossover events can take place at most points along each chromosome. The X and Y chromosomes undergo no crossover events{{ safesubst:#invoke:Unsubst||date=__DATE__ |$B= {{#invoke:Category handler|main}}{{#invoke:Category handler|main}}[citation needed] }} and are therefore excluded from the calculation. The mitochondrial DNA is only inherited from the maternal parent.

Fertilisation sections
Intro  History  Fertilization in plants   Fertilisation in animals   Fertilization in fungi  Fertilization in protists   Fertilisation and genetic recombination   Parthenogenesis  Allogamy and autogamy  Other variants of bisexual reproduction  Benefits of cross-fertilization  See also  References  External links  

Fertilisation and genetic recombination
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