Pedigrees and Pedigree Charts�Biology

Objective: Students will know what a pedigree is and be able to interpret pedigree charts

Pedigrees and Pedigree Charts

Pedigrees explain how a trait is passed from one generation to the next

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Pedigree charts visually

represent a pedigree

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Symbols show traits,

gender, relationships

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Why are Pedigrees Useful?

Many diseases can run in families. A family’s history of diseases is considered one of the best screening tools.

Genetic counselors create pedigree charts to lean more about diseases in families.

Early identification of diseases can help individuals to lead healthier lifestyles.

Interpreting a Pedigree Chart

• Shapes (biological sex)
• Square = male
• Circle = female
• Lines and connections
• Horizontal lines = marriage/mating
• Vertical lines = offspring
• Filling
• Clear = doesn’t show trait
• Solid Dark = shows trait
• Dark/Clear = has recessive allele but does not show trait (carrier)

Example: Sickle-cell Anemia

Example: Hemophilia in European Royalty