BOLOGY 107 Lecture 22Outline of Last Lecture I. Mendelian Geneticsa. Polymorphism b. Genetics c. Problems with MendelII.Outline of Current Lecture III. Geneticsa. Punnett square b. Laws of independent assortmentc. Probabilityd. Test crossCurrent LectureGenetics1) Punnett squarea) Table used to predict possible outcomes from a genetic crossi) Place the parents genomes along the axes, fill in for progenyii) Deduce phenotype ratio2) Laws of independent assortmenta) Dihybrid cross- cross involving two traits(1) Example: RRYY (round, yellow pea) and rryy (wrinkled, green pea)ii) Random assortment of all traits leading to a 9:3:3:1 ratio(1) Genes for different traits assort randomly during gametogenesis(2) All possible combinations of phenotype can be seen(3) Distinct trait combinations are seen in children that are not seen in parents (round, green pea)3) Probability a) Likelihood that a specific possible outcome will occur.i) (specific outcome)/(total of outcomes)b) Addition rule- probability of multiple outcomes is the sum of the probabilities for each eventi) Either/or result statementsThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.c) Multiplication rule- probability of independent events occurring together is the product of each independent eventi) And/then result statementsd) Can use either punnett square or probability rules to get basic ratiosi) Easier to use probability rules if more than two traits are being considered4) Test crossa) Experimental cross to determine the genotype of a parent displaying the dominant phenotypei) Cross with the homozygous recessive (1) If the parent is homozygous dominant, then all progeny will show the dominant phenotype(2) If the parent is heterozygous recessive, then there will be some progeny showing the recessive
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