1. Pedigree Charts The family tree of genetics http://www.schooltube.com/video/c188ce8266b54a18992b/

2. Write these notes on the bottom half of page 63… To understand a pedigree, you first have to figure out whether the trait being studied is:  Sex-linked: (x-linked) Found on 23 rd pair. –Most males are affected –Very few females are affected  Autosomal: NOT sex-linked. Found on pairs 1-22. –Men and women have equal chance of being affected  Dominant: –Need one or more dominant allele (D_) –1 parent MUST have the disorder  Recessive: –Need two copies of recessive allele to have disorder –Neither parent has to have disorder because they can be heterozygous (carrier)

3. Pedigree Charts I II III

4. Overview I. What is a pedigree? a. Definition b. Uses II. Constructing a pedigree a. Symbols b. Connecting the symbols III. Interpreting a pedigree

5. What is a Pedigree?  A pedigree is a chart of the genetic history of family over several generations.  Scientists or a genetic counselor would find out about your family history and make this chart to analyze.

6. Constructing a Pedigree  Male  Female

7. Connecting Pedigree Symbols  Married Couple  Siblings Examples of connected symbols:

8. Connecting Pedigree Symbols  Fraternal twins  Identical twins Examples of connected symbols:

9. Example  What does a pedigree chart look like?

10. Symbols in a Pedigree Chart  Affected  X-linked  Autosomal carrier  Deceased

11. Interpreting a Pedigree Chart 1. Determine if the pedigree chart shows an autosomal or X-linked disease. –If most of the males in the pedigree are affected the disorder is X-linked –If it is a 50/50 ratio between men and women the disorder is autosomal.

12. Example of Pedigree Charts  Is it Autosomal or X-linked?

13. Answer  Autosomal

14. Interpreting a Pedigree Chart 2. Determine whether the disorder is dominant or recessive. –If the disorder is dominant, one of the parents must have the disorder. –If the disorder is recessive, neither parent has to have the disorder because they can be heterozygous.

15. Example of Pedigree Charts  Dominant or Recessive?

16. Answer  Dominant

17. Example of Pedigree Charts  Dominant or Recessive?

18. Answer  Recessive

19. Summary  Pedigrees are family trees that explain your genetic history.  Pedigrees are used to find out the probability of a child having a disorder in a particular family.  To begin to interpret a pedigree, determine if the disease or condition is autosomal or X-linked and dominant or recessive.