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Title: Incomplete Penetrence, Variable Expressivity, and Epistasis Post by: rjbrivera on Mar 4, 2015 In a type of parakeet known as a "budgie," feather color is controlled by two genes. A yellow pigment is synthesized under the control of a dominant allele Y. Budgies that are homozygous for the recessive y allele do not synthesize yellow pigment. At an independently assorting gene, the dominant allele B directs synthesis of a blue pigment. Recessive homozygotes with the bb genotype do not produce blue pigment. Budgies that produce both yellow and blue pigments have green feathers; those that produce only yellow pigment or only blue pigment have yellow or blue feathers, respectively; and budgies that produce neither pigment are white (albino).
The cross of a yellow budgie and an albino budgie produces offspring that are 8 yellow and 8 albino. What are the genotypes of the parents? Title: Re: Incomplete Penetrence, Variable Expressivity, and Epistasis Post by: wizarddim on Mar 4, 2015 In a type of parakeet known as a “budgie”, feather color is controlled by two genes.
A yellow pigment is synthesized under control of a dominant allele Y. Recessive homozygotes with the yy genotype homozygous do not synthesize yellow pigment. ---------yy the dominant allele B directs synthesis of a blue pigment. Recessive homozygotes with the bb genotype do not produce blue pigment.----------bb Budgies that produce both yellow and blue pigments have green feathers; those that produce only the yellow pigment or only the blue pigment have yellow or blue feathers, respectively; and budgies that produce neither pigment are white (albino). A cross of a green budgie and a yellow budgie produces offspring that are 12 green, 4 blue, 13 yellow, and 3 albino. What are the genotypes of the parents? Y_B_ =green; yyB_ = blue; Y_bb = yellow and yybb = white YyBb and yyBb --------------genotypes of the parents |