BIOL207 Lecture Notes - Lecture 11: Lethal Allele, Pleiotropy, Zygosity
8 Oct 2013
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Lecture 11: interactions between alleles of one gene | lecture 12: Purple flowers, in comparison to their white counterparts, have a p-gene that make an enzyme for purple pigment (anthrocyanin) For pea plants, the round seeds have an a-gene that makes a starch-branching enzyme: wrinkled peas are made because they do not produce this enzyme. The extra glucose makes the peas swell and then shrink to form wrinkles. Parents = red and white; offspring = pink) 100% allele activity = red pigmented plant. 50% allele activity = pink pigmented plant. 0% allele activity = white (colourless) plant. Codominance: heterozygotes display both parental phenotypes of a gene expression. Lethal alleles: heterozygous offspring exhibit a different phenotype than a pure-breeding dominant genotype but. If the offspring is homozygous for the recessive allele, it will die. Because that allele prevents activity of an essential gene for living (organisms becomes non-viable)
