NOTES 23 - PedigreesNOTES 23 - Pedigrees

What is a pedigree?What is a pedigree? PedigreePedigree – A picture of an individual’s – A picture of an individual’s

family tree that shows which members of family tree that shows which members of the family have a particular trait and how the family have a particular trait and how the trait has been passed from one the trait has been passed from one generation to the nextgeneration to the next

Drawing a pedigree:Drawing a pedigree:

= Male= Male

= = FemaleFemale

= Parents= Parents

= Offspring= Offspring

If the pedigree is for a If the pedigree is for a recessiverecessive trait:trait:

= Does not have trait = Does not have trait (homozygous dominant)(homozygous dominant)

= Does not have trait, but = Does not have trait, but carries recessive allele carries recessive allele (heterozygous)(heterozygous)

= Has trait (homozygous = Has trait (homozygous recessive)recessive)

If the pedigree is for a If the pedigree is for a dominantdominant trait:trait:

= Does not have trait = Does not have trait (homozygous recessive)(homozygous recessive)

= Has trait (homozygous = Has trait (homozygous dominant OR dominant OR heterozygous)heterozygous)

A A RecessiveRecessive PedigreePedigreeBlue eye colorBlue eye color

Ex. A recessive pedigree for Ex. A recessive pedigree for blue eye color (blue eye color (BB = non-blue = non-blue bb = blue) = blue)

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

Since the pedigree is for blue eyes, Since the pedigree is for blue eyes, completely shade in all blue-eyed completely shade in all blue-eyed peoplepeople

Generation 1 – No blue eyesGeneration 1 – No blue eyes Generation 2 – Persons 2 and 3 have blue eyesGeneration 2 – Persons 2 and 3 have blue eyes Generation 3 – Person 6 has blue eyesGeneration 3 – Person 6 has blue eyes

Since the pedigree is for blue eyes, Since the pedigree is for blue eyes, completely shade in all blue-eyed completely shade in all blue-eyed peoplepeople

Generation 1 – No blue eyesGeneration 1 – No blue eyes Generation 2 – Persons 2 and 3 have blue eyesGeneration 2 – Persons 2 and 3 have blue eyes Generation 3 – Person 6 has blue eyesGeneration 3 – Person 6 has blue eyes

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

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

A A DominantDominant PedigreePedigree

Non-blue eye colorNon-blue eye color

Ex. A dominant pedigree for non-Ex. A dominant pedigree for non-blue eye color (blue eye color (BB = non-blue = non-blue bb = blue)= blue)

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

blue eyesblue eyes

Since the pedigree is for non-blue eyes, Since the pedigree is for non-blue eyes, completely shade in the non-blue eyed completely shade in the non-blue eyed peoplepeople

Generation 1 – Persons 1 and 2 have non-blue eyesGeneration 1 – Persons 1 and 2 have non-blue eyes Generation 2 – Persons 1 and 4 have non-blue eyesGeneration 2 – Persons 1 and 4 have non-blue eyes Generation 3 – Persons 1,2,3,4,5,7 and 8 have non-blue eyesGeneration 3 – Persons 1,2,3,4,5,7 and 8 have non-blue eyes

Since the pedigree is for non-blue eyes, Since the pedigree is for non-blue eyes, completely shade in the non-blue eyed completely shade in the non-blue eyed peoplepeople

Generation 1 – Persons 1 and 2 have non-blue eyesGeneration 1 – Persons 1 and 2 have non-blue eyes Generation 2 – Persons 1 and 4 have non-blue eyesGeneration 2 – Persons 1 and 4 have non-blue eyes Generation 3 – Persons 1,2,3,4,5,7 and 8 have non-blue eyesGeneration 3 – Persons 1,2,3,4,5,7 and 8 have non-blue eyes

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