Two trait genetic crosses & pedigrees

1. Two trait genetic crosses & pedigrees

2. Crossing Two Traits Cross a heterozygous purple, heterozygous smooth corn plant with a corn plant that is yellow and wrinkled. Purple = P Yellow = p Smooth = S Wrinkled = s P = PpSs x ppss

3. P = PpSs x ppss Step #1 Determine genotypes of parents. Step #2 Determine the gametes of each parent. Step #3 Set up Punnett Squares ps PS Ps pS ps x

4. PpSs ppss ps PpSs PS 25% Purple & Smooth Ppss Ps 25% Purple & Wrinkled pS ppSs 25% Yellow & Smooth ppss ps 25% Yellow & Wrinkled

5. What is a dihybrid cross? P = TtAa x TtAa ta TA Ta tA TA TTAa TtAA TTAA TtAa Ta TTAa Ttaa TTaa TtAa tA TtAA TtAa ttAA ttAa ta TtAa Ttaa ttAa ttaa

6. Dihybrid Cross Ratio 9/16 Tall & Axial (Dom & Dom) 3/16 Tall & Terminal (Dom & Rec) 3/16 Short & Axial (Rec & Dom) 1/16 Short & Terminal (Rec & Rec)

7. Pedigrees • A pedigree is a type of family tree that shows the sex of the individuals and the phenotype of that individual for a single trait • Circles are female ,squares are male • Filled in has the ‘affected’phenotype, open has the ‘unaffected’ • The trait examined can either be dominant or recessive • A person who has the trait but does not express it is a “carrier” • (heterozygous for a recessive trait)

8. Using Pedigrees • A pedigree can be used to determine the genotype of individuals in a family • It can be used to track a, dominant, recessive , or sex-linked trait • Pair share: is the trait dominant or receive? How do you know? If it is recessive are there any carriers?

9. What does this pedigree tell us?

10. White board Review • What are the 3 steps of determining a dihybrid cross? • What does “di” mean? • What is a pedigree?