1. Studying Heredity Pedigrees Notes

2. What is a pedigree? 1. A pedigree is a diagram of family relationships that uses symbols to represent people and lines to represent genetic relationships. 2. They are often used to determine the mode of inheritance (dominant, recessive, etc.) of genetic diseases

3. 3. Squares represent males 4. Circles represent females 5. If the purpose of a pedigree is to analyze the pattern of inheritance of a particular trait, it is customary to shade in the symbol of all individuals that possess this trait.

4. If the trait in question is a genetic disease or abnormality… 6.We will learn patterns of inheritance that have the following modes of inheritance: a.autosomal dominant b.autosomal recessive c.X-linked recessive

5. Autosomal dominant 7. An autosomal dominant trait is one that is on a non-sex chromosome and is a dominant allele. 8. Can this disorder be a dominant trait? aaAa aa Yes

6. More autosomal dominant How about this one? No! Aa aa

7. Common Autosomal Dominant Disorders Marfan’s Syndrome (connective tissue disorder) Huntington’s Disease

8. Autosomal recessive 9. An autosomal recessive trait is one that is on a non-sex chromosome and is a recessive allele 10. Can this disorder be a recessive trait? aa aa???

9. More autosomal recessive What about this one? Aa aaAa or AA

10. Common Autosomal Recessive Disorders Sickle Cell Anemia Cystic Fibrosis

11. X-linked recessive 11. An X-linked recessive trait is a trait that is carried on the X chromosome 12. Males are more at risk to exhibit the trait since they only have one copy of the allele in question! a.X A = normal b.X a = the trait (a genetic disease or abnormality) c.Y = Y chromosome (males only)

12. X-linked recessive Could this represent an X-linked recessive trait? X A YX a X a Y

13. More X-linked recessive How about this one? X a X A Y X a Y

14. X-linked with an unaffected mother… How about this one? X A X a X a Y

15. Common X Linked Recessive Traits Male Pattern Baldness Color Blindness Hemophila

16. 2 reasons NOT to marry your cousins… British Royal Family- Haemophilia Habsburg Chin- German Royal Family