1. Work sheet on co-dominance and incomplete dominance

2. Co-Dominance
Up until now you have been working on the idea that one strong gene hides a weak gene; this is called simple dominance.
Now we are going to learn about two other patterns of inheritance. x R W RW
Co-dominance: When you cross 2 pure lines and the F1 show equal expression of both traits.
Red flowers x White flowers gives you red and white stripes

3. Incomplete Dominance Incomplete dominance: when you cross 2 pure lines
and the F1 blended expression of both traits.
Red flowers x White flowers gives you pink flowers. x R W RR RW WW

4. Classic phenotypic ratio
In both cases, because the alleles are equal strength you use capital letters for each allele.
In both cases if you cross the F1 you get a classical phenotypical ratio of
1 : 2: 1 or 1: 2: 1
Red: Striped: Red Red: Pink: Red

5. practise
1. Four O’clocks are flowers that are renowned for incomplete dominance. What would the offspring look like(Phenotype)if you crossed:
a) a red flower with a pink flower
b) a red flower with a white flower
c) a white flower with a pink flower
d) 2 pink flowers
Let: R=red, W=white Find the phenotypic ratio of each F1 generation
Given: a) RR x RW b) RR x WW c) WW x RW d) RW xRW
F1: : % 1 : : : 1
Red:Pink Pink Pink : White Red : Pink : White