Genetics and Probability Flipping Coins Heads vs Tails

Genetics and Probability

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

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 Total Probability = ½ x ½ = ¼

Probability of tt = • ½x½=¼ Probability of Tt • 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

T T t t

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

Cross: TT x tt o Probability of Tt: Cross: Tt x tt o Probability of Tt o Probability of tt o Probability of TT

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

Cross Aa. Bb x Aa. Bb o Probability of Aa. Bb • Probability of Aa = ½ • Probability of Bb = ½ • Probability of Aa. Bb = ½ x ½ = ¼ - Probability of AABB - Probability of Aabb

Cross Aa. BBCc x AABb. Cc o Probability of AABBCC o Probability of Aa. Bb. Cc o Probability of AAbb. CC