In Drosophila, the autosomal recessive pr and cn mutations cause brown and bright-red eyes, respectively (wild-type flies have brick-red eyes). Flies who are homozygous recessive at both pr and cn have orange eyes. A female who has wild-type eyes is crossed to an orange-eyed male. Their progeny have the following distribution of eye colors: 10 wild-type 240 brown 240 bright red 10 orange The mother of these progeny resulted from a cross between flies from two true-breeding lines. What are the genotypes of these two lines?
Added by Sarah G.
Step 1
We know that the female has wild-type eyes, so she must have at least one dominant allele for each gene (PR and CN). Since she is the offspring of two true-breeding lines, she must be heterozygous for both genes (Prpr and Cncn). So her genotype is PrprCncn. Show more…
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In Drosophila, the autosomal recessive pr and cn mutations cause brown and bright-red eyes, respectively (wild-type flies have brick-red eyes). Flies who are homozygous recessive at both pr and cn have orange eyes. A female who has wild-type eyes is crossed to an orange-eyed male. Their progeny have the following distribution of eye colors: wild-type 8 brown 241 bright-red 239 orange 12 total 500 a) What phenotypes are parental? (2 points) b) What is the map distance between genes pr and cn? (4 points)
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In Drosophila, the autosomal recessive pr and cn mutations cause brown and bright-red eyes, respectively (wild-type flies have brick-red eyes). Flies who are homozygous recessive at both pr and cn have orange eyes. A female who has wild-type eyes is crossed to an orange-eyed male. Their progeny have the following distribution of eye colors: wild-type brown bright-red orange 8 241 239 12 total 500 a) What phenotypes are parental? (2 points) b) What is the map distance between genes pr and cn? (4 points)
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In flies, the recessive pr and cn mutations cause brown and bright-red eyes, respectively. Wild-type flies have brick-red eyes, while the double mutant pr cn combination has orange eyes. Now, a brick-red-eyed female with an unknown genotype was bred with an orange-eyed male. Their progeny have the following distribution of eye colors. Brick-red: 190 Brown: 10 Bright red: 10 Orange: 190 Total: 400 1) Write the genotype of the brick-red-eyed female based on her progeny. 2) Write the genotype of the orange-eyed male.
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