1. Punnett Squares
Spring 2018

2. Punnett Squares Reginald Punnett came up with Punnett squares
Father’s genotype
Reginald Punnett came up with Punnett squares
They predict the proportions of possible genotypes in offspring.
This shows a Punnett square for a SINGLE trait- monohybrid cross.
Mother’s genotype

3. Monohybrid Cross: Heterozygous Plants
Crossing two pea plants that are heterozygous for seed color (Yy) will produce offspring in the following ratio:
¼ = YY (Homozygous dominant)
2/4 = (Heterozygous)
¼ = (Homozygous recessive)

4. Monohybrid Cross: Homozygous Plants
A cross between a green homozygous plant (YY) with a homozygous recessive yellow plant (yy) only produces heterozygous (Yy) offspring.
4/4 = Yy (Heterozygous)

5. Dihybrid Cross
A Punnett square can also be created for dihybrid crosses.
It would be FOUR boxes wide and FOUR boxes tall!