WORK SHEET ON CODOMINANCE AND INCOMPLETE DOMINANCE CoDominance

WORK SHEET ON CO-DOMINANCE AND INCOMPLETE DOMINANCE

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 R Co-dominance: When you cross 2 pure lines and the F 1 show equal expression of both traits. W RW RW Red flowers x White flowers gives you red and white stripes W RW RW

Incomplete Dominance ◦ Incomplete dominance: when you cross 2 pure lines ◦ and the F 1 blended expression of both traits. ◦ Red flowers x White flowers gives you pink flowers. x R W R RR RW WW

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 F 1 you get a classical phenotypical ratio of ◦ 1 : 2: 1 ◦ Red: Striped: Red or 1: 2: Red: Pink: Red 1

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 ◦ Given: a) RR x RW ◦ F 1: 1 : 1 Red: Pink Find the phenotypic ratio of each F 1 generation b) RR x WW 100% Pink c) WW x RW 1 : 1 Pink : White d) RW x. RW 1 : 2 : 1 Red : Pink : White