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.