- Rules of probability can be applied to analyze passage of single-gene traits from the parent to the offspring.
For harder problems, where there are 2 alleles (AaBb) 
- Mutually exclusive (can’t happen at same time) = or
Multiplication Rule
- Two or more independent events (and)
- Find the probability of each individual alleles, then multiply the two by each other
- Memorize cross probabilities
- Rr x rr = ½ Rr & ½ rr
- Rr x RR = ½ Rr & ½ RR (probability of dominant phenotype is 1)
- Rr x Rr = ¼ RR, ½ Rr & ¼ rr (probability of dominant phenotype is .75)
- RR x rr = 4/4 Rr (probability of dominant is 1)
Finding Number of Unique Gametes Given Genotype
- Aa=2, AA=1, aa= 1
Add up. Ex AaBbCCDdEE = 8