1. Punnett Squares

2. Punnett Squares : A model used to show the possible ways genes can
combine during fertilization.

3. Punnett Squares
Punnett Squares
Helps you keep
track of traits.

4. Dominant and recessive alleles are represented by letters.
Punnett Squares
Dominant and recessive alleles
are represented by letters.

5. Punnett Squares
A capital letter (T) is used for dominant alleles. T

6. A lowercase letter (t) is used for recessive alleles.
Punnett Squares
A lowercase letter (t) is used for recessive alleles. t

7. Punnett Squares
If you wanted to know the type of offspring a cross between two parents would produce, you can use a punnett square.
Tt x Tt
TT,Tt for tall
Tt for short

8. Punnett Squares
The letters representing the alleles from one parent are placed along the top of the square.
T t

9. Punnett Squares
The letters representing the two alleles from the second
Parent are places along the side of the square. T t

10. Punnett Squares
T t x T t
T t T t

11. Punnett Squares
Squares are filled by writing the letter at the top beside the letter on the side.
T t TT Tt
t t T t

12. Punnett Squares
The letters in each of the squares represents the Genotypes of the offspring that the parents could produce. TT Tt
t t
T t TT Tt
t t T t

13. Punnett Squares
The genotype (genetic makeup) can be used to predict the phenotype (physical appearance) of the offspring.

14. Punnett Sqaures
Genotype Phenotype
TT tall
Tt tall
Tt tall
t t short

15. Punnett Squares
Probability: the ratio that a particular event could occur.
3:1
3 would be tall
1 would be short
out of 4 offspring

16. Punnett Squares: Help you keep track of traits.
Predict genotype and phenotype.
Calculate probability.