1. Pedigrees – NOT the dog food!

2. What does pedigree mean?
Pedigree: a diagram that traces one trait through several generations of a family

3. = female
= male

4. Example #1 3 2 How many girls? ___ How many boys? ___ mom dad
daughter #1
daughter #2
son

5. mom
dad
oldest
youngest
daughter #1
daughter #2
son

6. A horizontal line connecting two shapes represents a cross/marriage.
mom
dad

7. Example #2
How many crosses/marriages? 2 A B C D E F G

8. A vertical line extending down from a marriage/cross represents that the couple has children.
mom
dad

9. ? Example #3 4 How many couples have children? H A B G H C D E F J K LQ R S T

10. How do you show twins? A B C D E F

11. **A pedigree chart follows one trait.
How do you show traits?
Shading
( shaded = recessive ) RR Rr rr
mutation
**A pedigree chart follows one trait.

12. Rr
mom RR
dad
R = tongue roller
r = non-roller Rr
son Rr
daughter RR
daughter
R R R r RR RR Rr Rr

13. A B C D E F H G K J L M N O P R Q S T
Practice questions…

14. What is wrong with this pedigree chart?
This offspring cannot receive 2 recessive genes.
This offspring cannot receive 2 recessive genes.
This offspring cannot receive 2 dominant genes.

15. What are possible genotypes for individual W?
R r
W could be RR (no shading) or Rr (half-shaded) or rr (all shaded). R r RR Rr Rr rr

16. If you have 1 recessive, you are a carrier, but you are not sick.
Pedigree charts help to trace genetic diseases. Most genetic diseases are a recessive gene.
If you have 1 recessive, you are a carrier, but you are not sick.
If you have 2 recessive genes, you are sick with the disease. (you are “affected”) Aa aa

17. 4 3 1 rr Rr 7 Granddaughter, carrier, 3rd generation, older sibling
Grandson, carrier, 3rd generation, middle sibling 1 rr Rr 7

18. A person that carries one copy of the disease gene, but it is masked by the dominant trait. (hybrid)2 U
U is further left. This makes U older than V