Jumpstart 11/27 Create a Venn Diagram comparing monohybrid and dihybrid crosses. Your venn should have at least 5 differences and 3 similarities.

THE DIHYBRID CROSS Studying the inheritance of two traits simultaneously (at the same time) © 2007 Paul Billiet ODWSODWS

Mendel’s peas CharacterTraitAllele Seed shapeRoundR Wrinkledr Seed colorYellowY Greeny © 2007 Paul Billiet ODWSODWS

Combinations GenotypePhenotype RRYYRound Yellow RRYyRound Yellow RrYYRound Yellow RrYyRound Yellow RRyyRound Green RryyRound Green rrYYWrinkled Yellow rrYyWrinkled Yellow rryyWrinkled Green © 2007 Paul Billiet ODWSODWS

THE LAW OF INDEPENDENT ASSORTMENT It appears that the inheritance of seed shape has no influence over the inheritance of seed color The two traits are inherited INDEPENDENTLY The pairs of alleles that control these two traits assort themselves independently © 2007 Paul Billiet ODWSODWS

Mendel & Meiosis The pairs of chromosomes could orientate in different ways at Anaphase 1 © 2007 Paul Billiet ODWSODWS

PPhenotypesRound Yellow seed XWrinkled Green seed (Pure bred) GenotypesRRYYrryy meiosis GametesRYry fertilization F1F1 PhenotypesRrYy GenotypesRound Yellow Proportions100% Dihybrid cross genetic diagram © 2007 Paul Billiet ODWSODWS

When working with Dihybrid Crosses we use the FOIL method Example of a Dihybrid Genotype Bb CC First Outside Inside Last BC BC bC bC

Examples of FOIL- Use these parental genotypes to find the possible gametes: 1.RrTt 2.RRTT 3.rrTt 4.RRTt 5.Rrtt No need to repeat gametes if they are the same…pay close attention!

Steps for working genetics probs with 2 traits: 1.Assign alleles (what letters do you wanna use?) 2.Determine genotypes of the Parents (P generation) 3.Find gametes using FOIL method. 4.For each parent, cross off any repeats, they are unnecessary!! (WHOO HOO….a shortcut!) 5.Do your Punnett Square (drag n’ drop) 6.Figure it out! Analyze your Punnett square to answer the question.

In mice, running is dominant to waltzing, and black coat color is dominant to white. Use a punnet square to predict the results of a cross between a heterozygous running, white mouse and a waltzing, heterozygous black mouse. *First we need to FOIL out the genotypes ____ ____, ____ ____ X ____ ____, ____ ____F:O:I:L:

Example #2 For the same pea plants: (yellow dominant over green; and smooth dominant over wrinkled Cross 2 pea plants that are both heterozygous for BOTH traits. 1.What are the Parent genotypes? 2.Possible gametes? 3.Punnett Square? 4.Phenotypic ratio?

Example #1 NOW, for a shortcut!!!! Mendel worked with peas, so let’s take an example from him: In pea plants, yellow color is dominant to green, and smooth seeds are dominant to wrinkled seeds. If a green and wrinkled plant is crossed with a homozygous yellow wrinkled plant, what would be the phenotypic ratio for the offspring?