1. Do now activity #3
In pea plants, yellow seed color (Y) is dominant over green seed color ( y ). Complete the cross between a plant that is heterozygous for yellow seeds and a plant that is homozygous recessive.

2. Heterozygous for Yellow Seeds
Practice Question!
Heterozygous for Yellow Seeds
And
Homozygous Recessive.
Y y y
Y y
y y
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Y y
y y

3. There is a 50% chance that the plant will have yellow seeds.
Practice Question!
There is a 50% chance that the plant will have yellow seeds.
Y y y
Y y
y y
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Y y
y y

4. There is a 50% chance that the plant will have green seeds.
Practice Question!
There is a 50% chance that the plant will have green seeds.
Y y y
Y y
y y
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Y y
y y

5. Section 3-3: Punnet Squares
Essential Question:
If you know parent genotypes, how can you predict the probability of offspring genotypes and phenotypes?
Key-terms: punnet square, phenotype, genotype, law of segregation, dominant, recessive
Learning Target
Use a punnett square to predict the probability of offspring genotypes and phenotypes based on the parents genotype.
Section 3-3: Punnet Squares

6. Don’t forget to chunk your notes!

7. Probability: the likelihood that an event will occur.
overview
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Probability: the likelihood that an event will occur.

8. When you flip a coin, what is the probability that you will get Tails?
overview
When you flip a coin, what is the probability that you will get Tails?
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9. The probability of a particular event occurring from a coin toss is
overview
Example: Coin Toss
The probability of a particular event occurring from a coin toss is
½ or 50%
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10. overview Example: Coin Toss Possible events:
Heads = ½ or 50% probability
Tails = ½ or 50% probability
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11. overview
Is it possible to flip a coin 10 times, and the coin lands on tails every time?
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12. Don’t forget to chunk your notes!

13. Traits
Based on genetic information, we can use a Punnet Square to determine the probable traits of our children.
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14. Traits are controlled by genes
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15. Question!
Who do
you receive genes from?
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How?

16. Don’t forget to chunk your notes!

17. How to do a punnet Square
Steps
Define your letters
Set up your cross-breed
Draw your Punnet Square
Law of Segregation
Solve the Punnet Square
Calculate probabilities
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18. Alleles separate during ______ formation
Law of segregation
Alleles separate during ______ formation
gamete
gamete

19. Law of segregation Dominant Allele
The trait is always seen in phenotype
Shown by a capital letter
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20. Law of segregation Recessive Allele
Trait is seen in phenotype when a dominant allele is not there
Shown by lowercase letter
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21. Practice Problem
Dimples (D) is dominant over no dimples (d). A woman heterozygous for dimples has a child with a man heterozygous for dimples. *Use a punnet square to determine the probability of the couple having a child without dimples.

22. Practice Question! And D d D d D D D d D d d d
Heterozygous for dimples
And
Heterozygous for dimples.
D d D d
D D
D d
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D d
d d

23. There is a 75% chance that the baby will have dimples.
Practice Question!
There is a 75% chance that the baby will have dimples.
D d D d
D D
D d
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D d
d d

24. There is a 25% chance that the baby will not have dimples.
Practice Question!
There is a 25% chance that the baby will not have dimples.
D d D d
D D
D d
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D d
d d

25. Gametes Segregation Parent Generation D d D d
Baby
Generation DD Dd Dd dd
Results: DD = Dimples Dd = Dimples dd = no dimples
75% Dimples & 25% No Dimples

26. Don’t forget to chunk your notes!

27. Types of Punnet squares
Mono-Hybrids: crosses between parents for a ______ trait.
Examples:
Dimples, Cleft chin, Freckles, Widow peak
single
single

28. Types of Punnet squares
Di-Hybrids: crosses between parents for two ________ traits.
Examples:
Hair-line AND Cleft chin
Dimples AND Freckles
different
different

29. Don’t forget to chunk your notes!