NOTES 23 - Pedigrees

What is a pedigree? Pedigree – A picture of an individual’s family tree that shows which members of the family have a particular trait and how the trait has been passed from one generation to the next Pedigree – A picture of an individual’s family tree that shows which members of the family have a particular trait and how the trait has been passed from one generation to the next

Drawing a pedigree: = Male = Male = Female = Female = Parents = Offspring

If the pedigree is for a recessive trait: = Does not have trait (homozygous dominant) = Does not have trait, but carries recessive allele (heterozygous) = Has trait (homozygous recessive)

If the pedigree is for a dominant trait: = Does not have trait (homozygous recessive) = Has trait (homozygous dominant OR heterozygous)

A Recessive Pedigree Blue eye color

Ex. A recessive pedigree for blue eye color (B = non-blue b = blue)

Use the following information to fill in the pedigree: Generation 1 – No blue eyes Generation 1 – No blue eyes Generation 2 – Persons 2 and 3 have blue eyes Generation 2 – Persons 2 and 3 have blue eyes Generation 3 – Person 6 has blue eyes Generation 3 – Person 6 has blue eyes

Since the pedigree is for blue eyes, completely shade in all blue-eyed people Generation 1 – No blue eyes Generation 1 – No blue eyes Generation 2 – Persons 2 and 3 have blue eyes Generation 2 – Persons 2 and 3 have blue eyes Generation 3 – Person 6 has blue eyes Generation 3 – Person 6 has blue eyes

Since the pedigree is for blue eyes, completely shade in all blue-eyed people Generation 1 – No blue eyes Generation 1 – No blue eyes Generation 2 – Persons 2 and 3 have blue eyes Generation 2 – Persons 2 and 3 have blue eyes Generation 3 – Person 6 has blue eyes Generation 3 – Person 6 has blue eyes

Since this is a recessive pedigree, there will be heterozygous carriers. Figure out who the carriers are and shade them in halfway. If you can’t figure out if a person is a carrier or is homozygous dominant, then put a question mark.

A Dominant Pedigree Non-blue eye color

Ex. A dominant pedigree for non-blue eye color (B = non-blue b = blue)

Use the following information to fill in the pedigree: Generation 1 – Persons 1 and 2 have non-blue eyes Generation 1 – Persons 1 and 2 have non-blue eyes Generation 2 – Persons 1 and 4 have non-blue eyes Generation 2 – Persons 1 and 4 have non-blue eyes Generation 3 – Persons 1,2,3,4,5,7 and 8 have non-blue eyes Generation 3 – Persons 1,2,3,4,5,7 and 8 have non-blue eyes

Since the pedigree is for non-blue eyes, completely shade in the non-blue eyed people Generation 1 – Persons 1 and 2 have non-blue eyes Generation 1 – Persons 1 and 2 have non-blue eyes Generation 2 – Persons 1 and 4 have non-blue eyes Generation 2 – Persons 1 and 4 have non-blue eyes Generation 3 – Persons 1,2,3,4,5,7 and 8 have non-blue eyes Generation 3 – Persons 1,2,3,4,5,7 and 8 have non-blue eyes

Since the pedigree is for non-blue eyes, completely shade in the non-blue eyed people Generation 1 – Persons 1 and 2 have non-blue eyes Generation 1 – Persons 1 and 2 have non-blue eyes Generation 2 – Persons 1 and 4 have non-blue eyes Generation 2 – Persons 1 and 4 have non-blue eyes Generation 3 – Persons 1,2,3,4,5,7 and 8 have non-blue eyes Generation 3 – Persons 1,2,3,4,5,7 and 8 have non-blue eyes

Since this is a dominant pedigree, there are no carriers, people left blank all have blue eyes