Autosomal Inheritance Bio 40S - Kelvin A trait expressed by a gene - - PowerPoint PPT Presentation

autosomal inheritance
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Autosomal Inheritance Bio 40S - Kelvin A trait expressed by a gene - - PowerPoint PPT Presentation

Autosomal Inheritance Bio 40S - Kelvin A trait expressed by a gene located on an autosomal chromosome. Autosomal Traits 22/ 23 Chromosomes are autosomal, the exception being the X/Y sex chromosomes (but more on that later) Remember:


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Autosomal Inheritance

Bio 40S - Kelvin

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Autosomal Traits

A trait expressed by a gene located

  • n an autosomal chromosome.

22/ 23 Chromosomes are autosomal, the exception being the X/Y sex chromosomes (but more on that later)

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Remember: Segregation and Independent Assortment

Mendel developed two extremely important genetic laws. Law of Segregation: The factors of inheritance (genes) are normally paired BUT are separated or segregated in the formation of gametes.

 The gene from each parent splits up, 50/50 chance of either

Law of Independent Assortment: Each factor’s distribution in the gametes is not related to the distribution of any other factor.

 Genes for hair colour and eye colour arrange separately.

Many unique combinations are thus possible

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Remember, the dominant gene masks the expression

  • f the recessive one.

Like we will see next

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Test cross

Sometimes you need to figure out the

genotype of an individual.

You can do this by crossing it with a

homozygous recessive individual.

See the image on the next page as an

explanation ☺

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A test cross is used to determine if a parent is homozygous

  • r heterozygous for

a dominant trait. This is done by crossing it with a homozygous recessive individual and observing the results in the

  • ffspring.