DIHYBRID GENETIC CROSSES
Class Notes Review
Solving Dihybrid genetic problems is not difficult, but it does take time! Follow these steps in order to solve any dihybrid problem.
1. Set up a chart with all the phenotypes and genotypes.
Example: Phenotype Genotypes
(Trait 1) Tall TT, Tt
(Trait 2) Red RR, Rr
2. Determine the Parent (P) genotypes.
Parents are Homozygous Dominant and Homozygous Recessive
TTRR and ttrr
3. Using the F O I L method set up the Punnett Square for four allele combinations.
(FOIL = First, Outer, Inner, Last)
4. Determine Genotypic and Phenotypic Ratio
F1 genotype is 100% TtRr (hybrid)
F1 phenotype is 100% Tall and Red