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Beyond Mendel’s Laws…. Looking at more complex types of inheritance where more than two phenotypes are possible!. 1. Incomplete Dominance. When red + white = pink!. Red Parent. White Parent. F R F R. F R F R. F W F W. F W F W. ∴ 3 phenotypes using only two alleles!. F R F W. F R F W.
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Beyond Mendel’s Laws… Looking at more complex types of inheritance where more than two phenotypes are possible!
1. Incomplete Dominance When red + white = pink!
Red Parent White Parent FRFR FRFR FWFW FWFW ∴ 3 phenotypes using only two alleles! FRFW FRFW FRFW FRFW Pink Offspring!
2. Co-dominance When black + white = black & white!
Chickens and Co-Dominance • Erminette chickens displayboth black and white “checkered” feathers • FBFB = black feathers • FBFW = black and white feathers (NOT grey!) • FWFW = white feathers • 3 phenotypes using only two alleles!
Impatiens and Co-Dominance • Impatiens can show co-dominance intheir colours • This one is COCW(orange and white) • COCO is orange • CWCW is white
3. Multiple Alleles More than 2 alleles… more than 2 phenotypes!
4. Polygenic Inheritance Multiple gene locations control a single trait, generating multiple phenotypes…
Assignment: Read and take notes from p. 142-145 and p. 178-180 in your textbook. Complete questions #5, 6, 7, 9, & 12 on p. 146.
