1. PUNNETT SQUARES

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3. PUNNETT SQUARES Punnett Square: A diagram that is used to predict the outcome of a cross between organisms  They show the results of any cross Target: I will be able to use Punnett Squares to predict the phenotype and genotype ratio of crosses involving one trait. Pg. 25

4.  Practice: Cross a homozygous purple plant and a homozygous white plant.P pppp Pp Genotypes: 1:1 Pp (100% Pp) Phenotypes: 1:1 Purple (100% Purple)

5. Hybrid Cross: A cross between two hybrids (Heterozygotes). Practice: Cross a heterozygous Tall plant and a Heterozygous Tall Plant. Note tall (T) is dominant over short (t) TtTt TtTt TT Tt tt Genotypes: 1TT :2Tt :1tt Phenotypes: 3 Tall: 1 Short

6. Test Cross: an individual of unknown genotype is mated with an individual showing the contrasting recessive trait. Dihybrid Cross: When there are two heterozygous traits that we are looking at. How to Solve a Dihybrid Cross: 1. Determine the parent genotypes, unless given 2. Determine the gametes using the FOIL method

7. 3. Set up a large 4x4 Punnett Square, place one gamete set from the parent on the top, and the other on the side 4. Solve like a typical Punnett Square but put the same letters together (TTGG; not TGTG)

8. Example- How to FOIL a Genotype to Determine Gametes: Parent Genotype: TtGg Tall = T Short = t Green = G yellow = g TtGg TGTgtGtg Summary:

9. PUNNETT SQUARE PRACTICE Seed Shape = Round (R)/Wrinkled (r) Rr x RR Seed shape = Round (R)/Wrinkled (r) Rr x Rr Plant Color = Green (G)/Yellow (g) GG x gg Pg. 26 Plant Color = Green (G)/Yellow (g) Gg x gg Plant height= Tall (T)/Short (t) Tt x TT Plant height= Tall (T)/Short (t) Tt x Tt Predict the offspring of this dihybrid cross: YyRr x YyRr (Y = Yellow Seed, y = Green Seed), R = Round, r = Wrinkled) For each Punnett Square- be sure to write the genotype ratios and phenotype ratios off to the side!!