Download - Pedigree Charts
Mrs StewartHonors Biology
Pedigree Charts
What is a pedigree?
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
Symbols
Pedigree Charts - Symbols
Pedigree Chart - Symbols
Pedigrees
Example: Hemophilia in the royal family
How is Hemophilia inherited?
Sex-Linked Recessive Disorder
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
Pedigrees
• Albinism • Polydactyly
Pedigree Chart
How do we read a Pedigree?
• Which family members are Albino?
• How is Ann related to Pam?
• Bill• Sam
Pam is Ann’s Grandmother
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.
What are the different ways a genetic condition can be inherited?
Autosomal Recessive• Skips generations• Affects males/females equally• Pedigree may show carriers
Autosomal Dominant• There will not be carriers – those with the
gene will be “affected”• Will probably not skip generations• Will affect males/females equally
Sex-Linked Recessive
• More males affected than females• Skips generations
What is the inheritance pattern for this disorder?
Autosomal Recessive
• How do we know?
– “affected” skips generations
– carriers
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.
PTC • The ability to taste PTC (bitter) is
inherited.
• BB = strong bitter taster• Bb = somewhat able to taste bitter• bb = cannot taste bitter
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.