Mrs Stewart Honors 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

Example: Hemophilia in the royal family What are some clues that you can see in this pedigree that could tell you this is a sex-linked disorder?

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.