1. Genetics and Probability

2. Flipping Coins Heads vs
Flipping Coins Heads vs. Tails Probability of Getting Heads = 50% or ½ Probability of Getting Tails = 50% or ½ Corresponds to Sorting of Gametes Tt = 50% chance of getting T and 50% chance of getting t

3. Calculating Multiple Probabilities
Calculating Receiving Gametes
Rule of Multiplication: The probability of a result is the product (multiply) of the individual probabilities.
Ex: Tt x Tt
The probability of getting TT
Probability of T = ½ Probability of T = ½
Total Probability = ½ x ½ = ¼

4. Probability of tt = Probability of Tt ½ x ½ = ¼ ½
WHY? Two Possible Ways of getting Tt from Tt x Tt
Tt or Tt
Each has an individual probability of ¼ so added together = ½

5. T t T t

6. Rule of Addition: If a result has multiple probabilities, the total probability of that result is the sum (addition) of the individual probabilities.

7. Cross: TT x tt Cross: Tt x tt Probability of Tt: Probability of Tt

8. Multiple Genes: Dihybrid and beyond
Find the individual probability of each gene pair and multiply all together.
Cross: AaBb X AABb
Probability of AaBB:
Probability of Aa = ½
Probability of BB = ¼
Total Probability of AaBB= ½ x ¼ = 1/8

9. Cross AaBb x AaBb Probability of AABB Probability of Aabb
Probability of Bb = ½
Probability of AaBb = ½ x ½ = ¼
Probability of AABB
Probability of Aabb

10. Cross AaBBCc x AABbCc Probability of AABBCC Probability of AaBbCc