Pedigrees – NOT the dog food!

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

= female = male

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

mom dad oldest youngest daughter #1 daughter #2 son

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

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

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

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

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

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

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

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

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.

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

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

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

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