1. Genetics Data and Probability
SBI3UP

2. Mendelian genetics demonstrates the rules of probability
The law of segregation and independent assortment are like tossing a coin or rolling dice.
Tossing a coin = ½ chance of tossing heads
Rolling dice = 1/6 chance of rolling a 2 and 5/6 chance of rolling another #
Probability ranges from 0-1 (no chance to 100% chance)

3. The outcome of one toss has no impact on the outcome of the next
Each toss is an independent event
Like the distribution of alleles into gametes
Each ovum from a heterozygous parent has a ½ chance of carrying the dominant allele and ½ chance of carrying the recessive allele
Same for sperm

4. Rules of Probability:
Rule of Multiplication
Rule of Addition

5. Rule of Multiplication
When to use:
Used to determine probability that 2+ independent events will occur together in a specific combination
How to use:
Calculate probability of each independent event
Multiply individual probabilities to get overall probability of events happening together

6. The probability that 2 coins tossed at the same time will land heads up is ½ x ½ = ¼
The probability that two heterogyzous pea plants (Pp) will produce a white-flowered offspring (pp) is ¼
½ of gametes from each parent carry the “p” allele
½ x ½ = ¼
This is the same info we can get from drawing a Punnett square, but w/o having to draw a Punnet square.

7. Example 1: What is the probability of a heterozygous parent (YyRr) of producing a YR gamete? Example 2: For a cross between two parents with genotypes YyRr, what is the probability that the offspring will have a YYRR genotype.

8. Example 3: In a cross b/t AaBbCc x AaBBCC what is the probability that the offspring will be AaBbCC?

9. 2. Rule of Addition:
When to use:
Used to determine the probability of an event occurring 2+ different ways
How to use:
Sum the probability of each different way

10. Example 4: If two heterozygous pea plants are crossed, what is the probability of the offspring being a heterozygote?

11. Example 5: In a cross b/t AaBbCc x AaBBCC what is the probability that the offspring will be AABbCc or AABBCC?