Gregor Mendel & Punnett Squares Monohybrid & Dihybrid Crosses https://www.youtube.com/watch?v=Mehz7t CxjSE Punnett Square Genotypes & phenotypes Using a Punnett Square Predicts the likely outcomes of a genetic cross with the alleles taken from the parents Shows all the genotypes that could result from a given cross Using Probability Likelihood that a specific event will occur Probability = # of one kind of possible outcomes total # of all possible outcomes Probability of a specific allele in a gamete Represented as a fraction or ratio Monohybrid Cross Cross involving a single trait All of the crosses involved the alleles for one gene only Dihybrid Cross Di= Two Hybrid=Combination Ex: A pea that is yellow and wrinkled crossed with a pea that is green and round Dominant Yellow ( Y ) Round ( R ) Recessive Green ( y ) Wrinkled ( r ) Cross: round green peas and yellow wrinkled peas Determine the parental genotypes Determine the gametes (FOIL method) Combine the 2 different genes for each parent to represent a sperm cell and an egg cell Set up a Punnet Square 4x4, place one gamete set from each parent on the top and side Write the genotypes and phenotypes of each offspring (ratios) Consider this cross A cross between two heterozygous peas for round, yellow seeds. What are the parents genotypes?