BIOL 3000 Lecture 9: More Modes of Inheritance
11 Feb 2017
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Document Summary
Basic mendelian rules apply for determining genotypes but expression as phenotypes will change. Example of incomplete dominance: snapdragon plants (important plant model for genetic studies) Parental generation (p1) red (rr) and white (rr) F1 generation rr (hybrid color/ almost blending of colors) 1/4 white (rr) 1/2 pink (rr) 1/4 red (rr) No way of having true breeding for pink however. Incomplete dominance-> expression of a heterozygous phenotype which is distinct from and often intermediate to that of either parent. Codominance condition in which the phenotypic effects of each allele are fully and simultaneously expressed in the heterozygote. Common single locus mode of inheritance at the molecular level. True red x true white=roan roan x roan= 1 red: 2 roan: 1 white. In cattle, polled condition (a) is dominant over the horned condition (a). Coat color is determined by codominant system that produces red (bb), roan (bb), and white (bb) phenotypes. Aa x aa = 3a_ : 1 aa.
