Laws of Probability Genetics AP Biology Probability Genetics

Laws of Probability & Genetics AP Biology

Probability & Genetics § Calculating probability of making a specific gamete is just like calculating the probability in flipping a coin § probability of tossing heads? 50% § probability making a P gamete… § Outcome of 1 toss has no impact on the outcome of the next toss § probability of tossing heads each time? 50% § probability making a P gamete each time? AP Biology

Rule of Addition § Chance that an event can occur 2 or more different ways u SUM of the separate probabilities § Use for heterozygous possibilities Two ways to be heterozygous: Pp or p. P u Key word is “or”. u § Ex: Probability of getting 2 or a 6 on the roll of a § die. 1/6 + 1/6 = 2/6 = 1/3 Ex: Probability of having offspring with dominant phenotype? PP or Pp or p. P ¼+ ¼ = ¾ AP Biology

Rule of multiplication § Chance that 2 or more independent events will occur together probability that 2 coins tossed at the same time will land heads up u probability of pp or PP offspring u § Ex: Probability of getting a head and a tail with two different coins. ½ x ½ = 1/4 u Key word is “and” u AP Biology

Calculating Probability of Pp x Pp ½ x ½ = ¼ = PP ½ x ½ = ¼ = pp § What about Pp? AP Biology

Calculating Dihybrid Probability § Rule of multiplication application with Dihybrid crosses: heterozygous parents — Yy. Rr u probability of producing yyrr? u probability of producing y gamete = 1/2 u probability of producing r gamete = 1/2 u probability of producing yr gamete u § = 1/2 x 1/2 = 1/4 u probability of producing a yyrr offspring § = 1/4 x 1/4 = 1/16 AP Biology