Biology 2581B Chapter Notes - Chapter 5.1: Zygosity, Antigen, Lethal Allele
11 Feb 2018
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5. 1 additional factors at a single locus can a ect the results of genetic crosses. How the phenotype of the heterozygote (aa) relates to the 2 homozygotes (aa, aa) Incomplete dominance > when the phenotype of heterozygote falls in between the phenotypes of the 2 homozygotes. Could be slightly towards 1 side, as long as the phenotype can be di erentiated from the 2 homozygotes. Produces 1:2:1 ratio in f2 gen. (not the 3:1 ratio we would"ve observed for complete dominance) Ex: egg plants purple (pp) eggplants x white (pp) eggplants > light purple violet (pp eggplants) Heterozygote simultaneously expresses the phenotypes of both homozygotes. Ex: mn blood-group that encodes the antigens on the surface of red blood cells. Mn antigens =/= abo antigens, they do not show a strong immunological reaction, so they"re not a factor in blood transfusions. Heterozygotes for both mn exhibit both m and n antigen.
