Autosomal InheritanceBio 40S - Kelvin

Autosomal

Traits

A trait expressed by a gene located on an autosomal chromosome.

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

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

Remember, the dominant gene masks the expression

of the recessive one.

Like we will see next

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 ☺

A test cross is used to determine if a parent is homozygous or heterozygous for a dominant trait.

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