Genetic Variation

01Genetic Variation

Independent segregation

This section covers how the independent segregation of homologous chromosomes produces different combinations of chromosomes in daughter cells.

Random orientation of homologous pairs

Independent segregation of homologous chromosomes is one reason meiosis produces genetically different daughter cells.

During meiosis I, homologous chromosome pairs line up at the equator. Each pair can orient in either direction, and the orientation of one pair does not determine the orientation of another pair.

When the homologous chromosomes separate, the chromosomes entering each daughter cell therefore depend on the random orientation of all the homologous pairs.

How this increases variation

Different combinations of the homologous chromosomes are separated into daughter cells. As a result, the gametes formed by meiosis can contain different combinations of alleles.

Exam Tip: Use the wording independent segregation of homologous chromosomes when explaining this source of variation.

02Genetic Variation

Crossing over

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Exchange of genetic material

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Recombination

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03Genetic Variation

Random fertilisation

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Random fusion of gametes

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Effect on genetic diversity

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04Genetic Variation

Chromosome combinations

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Combinations following meiosis

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2^{23}=8\,388\,608

Combinations following random fertilisation

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(2^n)^2

Nfw uffdan:

(2^{23})^2=70\,368\,744\,177\,664

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