The following example illustrates how both principles of probability can be combined to solve problems in genetics. Probability can also be a useful tool in predicting the results of dihybrid and trihybrid matings. For example, in mating AaBh x AaBh, one would expect 1/4 of the progeny to be AA, 2/4 Aa, and 1/4 aa, or 3/4 A- to 1/4 aa. Likewise, 1/4 should be BB, 2/4 Bh, and 1/4 bb, or 3/4 B- to 1/4 bh. Now, if t 3/4 x 3/4 -9/16 of the progeny to be A-B, 1/4 x 1/4 to be AAbb, and so forth. Use this ap- proach in answering the following series of questions. If AaBh is mated to AaBh, what is the prob- ability that the offspring will have e Ala) and B(b) genes are independently assorting, one would expect Principles of Probability 25. either the phenotype A-bh or the genotype auBB
