Pedigrees
Pedigrees Pedigrees show how a trait/disorder is passed from one generation to the next
Symbols:o Squares = males (XY), circles = females (XX)o Horizontal lines connect breeding coupleso Vertical lines connect parents to childreno Shading (filled in) = individual has the traito No shading = individual does not have the traito Half shading or a dot = a carriero A diagonal line means deatho Roman numerals show generationso Numbers assign an individual to a generation
Interpreting Pedigrees
Trait is dominant or recessive?
Skips a generation = recessive
Every generation = dominant
Trait is autosomal or sex linked?
Affects ♂ and ♀ equally → autosomal
Affects ♂ more than ♀ → sex-linked
Females tend to “carry” a trait and affect their sons
Females get the trait from affected father and carrier/affected mother
Affected males got it from their mother and give it to their daughters to “carry.”
Autosomal or Sex-linked? ____________________Is this dominant or recessive? ____________________Assign genotypes to the pedigree to show the inheritance pattern
aa
Aa
Aa
aa Aa Aa
Aa
Aa or AA
Aa
Aa
aa aa
aaaa
DominantAutosomal
Autosomal or Sex-linked? ____________________Is this dominant or recessive? ____________________Assign genotypes to the pedigree to show the inheritance pattern
Fill in what you know first!
Sex-linkedRecessive
XBY XBXb
XbY XBXb XBY
XBY
XBY
XbY
XbY XbY
XbY
XbY
XBXbXBXb
XBXb
XBXb
Pedigree with half-shading to show carriers