Evolution to Genetics 9 Pedigrees

9

Sex-Linked Recap:

Let’s consider X-linked recessive traits, like color blindness:

Females can be:

• Unaffected (XX)

• Carriers (XᴺXᶜ) — one normal allele and one affected allele

• Affected (XᶜXᶜ) — rare, needs two copies of the affected allele

Males can be:

• Unaffected (XᴺY)

• Affected (XᶜY) — only one copy of the affected gene is enough

Pedigrees

Pedigrees show the appearance of a phenotype through several generations of a family.  

In doing so, Pedigrees `map’ the pattern of a trait through a family.  Pedigrees are an investigative tool of geneticists. 

The pedigrees allow us to determine if a trait is caused by a dominant or recessive allele or if it is autosomal or sex-linked.

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