1. Genetics Punnett Squares

2. Punnett squares are a way to look at the gene pairs an offspring will inherit from their parents. It shows the probability of each match. For example: Say you are looking at the trait for height. T is the letter that represents the dominant trait for tall t is the letter that represents the trait for being short

3. Punnett Squares If you were looking at the gene pairs for a mother and father it might look like this: Mother = Tt (one allele for tallness, one for short) Father = tt (both alleles are for short) To see what the possible combinations of offspring would be you would set up a punnett square.

4. Mother = TtFather = tt T (mother) t (mother) t (father)  Tt t t (father)  Tt t 1.Put the 2 alleles for the 1 st parent in the top two boxes (right justified) 2.Put the 2 alleles for the 2 nd parent in the left side boxes (the top left corner box should be empty) 3.Carry the alleles down into the 2 squares below the 1 st parent 4.Carry the alleles across into the 2 squares to the right of the 2 nd parent 5.The 4 geneotypes inside squares are the possible offspring

5. Punnett Square Tt tTtTtt tTtTtt In the above example: Two of the possible geneotypes would be the dominant trait for Tall (Tt) (one of the alleles is dominant and one is recessive also known as heterozygous) Two of the possible geneotypes would be the recessive trait for SHORT (tt) (both of the alleles are the same also known as homozygous recessive ) Mother = TtFather = tt

6. Punnett Squares Mother = WW Father = Ww W = widows peak w = no widows peak WW WWW wWwWwWwWw In the example: Two possible offspring would be heterozygous (Ww) Two would be homozygous dominant (WW) All four possible geneotypes would be the dominant trait for Widows Peak (WW) and (Ww)

7. PUNNETT SQUARE PRACTICE! Plastic Egg Genetics