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Mrs Stewart Honors Biology Pedigree Charts

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What is a pedigree?

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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.