1. Probability & Punnett Squares

2. Probability
A concept that can be used to predict the results of a particular event
Examples
Chance of a specific team winning a sporting event
Chance of a coin landing on heads in a coin toss
Predict what is likely to occur, not necessarily what will actually occur

3. Probability and Punnett Squares
Punnett Square – A chart that shows how parents’ alleles might combine in an offspring
a tool that can help you understand the patterns of heredity
Geneticists use Punnett Squares to show all the possible outcomes of a genetic cross and to determine the probability of a particular outcome
Punnett Squares Explained at

4. Probability and Punnett Squares
What is the probabilty of…..
The offspring having a yellow seed color?
2 in 4
The offspring having a green seed color?

5. Probability and Punnett Squares
How else can probability be written?
The offspring having a yellow seed color?
2 in 4 or 50%
The offspring having a green seed color?

6. Using a Punnett Square
In rabbits, black fur color is dominant to white. What is the probability of producing a white rabbit if two heterozygous rabbits mate?

7. Let’s Practice
In pine trees, long needles are dominant over short needles. Cross a homozygous dominant plant with a plant that is heterozygous. What is the probability that the parents will produce offspring that have short needles? Give the genotypic and phenotypic ratios.

8. Let’s Practice
2. In cats, a striped coat is dominant over a solid coat. Cross a cat with a solid coat with a cat that is heterozygous for a striped coat. What is the probability that the parents will produce offspring with a solid coat? Give the genotypic and phenotypic ratios.

9. Let’s Practice
3. In humans, dark hair is dominant over light hair. Cross a man that is homozygous recessive with a woman that is homozygous dominant. What is the probability that the parents will produce offspring with light hair? Give the genotypic and phenotypic ratios.