Pedigree Charts Why do we use them? Then what information do we
use to determine inheritance of traits? Record ancestry and/or
trace the geneology of a trait through the family lines Genetic
Testing Medical History Historical Data Family Records
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Symbols
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Pedigree Charts - Symbols
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Pedigree Chart - Symbols
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Pedigrees
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Example: Hemophilia in the royal family
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How is Hemophilia inherited? Sex- Linked Recessive
Disorder
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What are some clues that you can see in this pedigree that
could tell you this is a sex- linked disorder? Example: Hemophilia
in the royal family
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Pedigrees Albinism Polydactyly
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Pedigree Chart
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How do we read a Pedigree? Which family members are Albino? How
is Ann related to Pam? Bill Sam Pam is Anns Grandmother
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What are Inheritance Patterns? Inheritance Pattern: The
transmission of genetically encoded traits/conditions/diseases to
offspring In other words: How the gene is transmitted/passed
on.
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What are the different ways a genetic condition can be
inherited?
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Autosomal Recessive Skips generations Affects males/females
equally Pedigree may show carriers
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Autosomal Dominant There will not be carriers those with the
gene will be affected Will probably not skip generations Will
affect males/females equally
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Sex-Linked Recessive More males affected than females Skips
generations
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What is the inheritance pattern for this disorder?
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Autosomal Recessive How do we know? affected skips generations
carriers
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Enrichment Assignment Create a family pedigree for the
following trait: Ability to taste bitter Mrs. Stewart has strips of
paper called PTC paper that will determine this ability.
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PTC The ability to taste PTC (bitter) is inherited. BB = strong
bitter taster Bb = somewhat able to taste bitter bb = cannot taste
bitter
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How to complete the enrichment assignment: 15 possible
enrichment points Have each family member (immediate household
family) taste the PTC paper. Use their responses to identify their
genotypes Create a pedigree that shows the trait throughout your
family 10 points extra if you include pictures of each family
member while tasting the PTC paper.