1 In a type of parakeet known as a budgie feather color is c

1. 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 ›t\' genotype homozygous 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 the yellow pigment or only the blue pigment have yellow or blue feathers, respectively; and budgies that produce neither pigment are white (albino).

List the genotypes for green, yellow, blue, and albino budgies.

A cross is made between a true-breeding green budgie and a true- breeding albino budgie. What are the genotypes of these two birds?

If F1 males and females are mated, what are the expected phenotypes and genotypes in the F2, and in what proportions?

The 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?

Solution

1. YYBB or YyBb or YYBb or YyBB ------------> Green; YYbb or Yybb -------> Yellow; yyBB or yyBb --------> Blue; yybb ------> Albino

2. true-breeding green budgie (YYBB) X true- breeding albino budgie (aabb)

3. F1 progeny are YyBb x YyBb -----------------> Phenotypic ratio: 9:3:3:1 & Genotypic ratio is 1:2:1:2:4:2:1:2:1

4. green budgie (YyBb) x  yellow budgie (YYbb)