Question

A researcher is studying genetic patterns in Drosophila melanogaster and is focusing on 3 specific phenotypes. The first is eye colour, with the phenotypes in question being red (wild) and brown. The gene responsible for these phenotypes is 'A' and has two alleles: A leads to red eyes and a leads to brown eyes. A is completely dominant to a. Also of interest are genes B and C, each with two alleles (B and b; C and c). Genes B and C determine fly colouration. Allele B produces flies that are very dark brown, verging on black, whereas allele b produces flies that are much lighter brown. Alleles B and b are incompletely dominant, meaning an in-between dark brown-red phenotype is also possible. Gene C is epistatic to gene B, meaning dominant allele C has to be present for gene B to be expressed at all. If a fly has genotype cc, then the B gene will not be expressed, regardless of genotype, and the flies end up with an almost orange colour. Finally, gene D is associated with the banding colouration pattern on an fly's abdomen. This gene has three alleles: D, d, and i. Allele D codes for horizontal bands, allele d codes for longitudinal bands, and allele i codes for no bands at all. Allele i is recessive, but alleles D and d are co-dominant. Imagine that, in an experimental context, a female fly was mated with a male. The female has the genotype AaBbCcDi, while the male has the genotype Aabbccdd. Knowing that all four genes in question are located on different chromosomes, approximately what proportion of the offspring are expected to be males with brown eyes that have the light brown body phenotype and only longitudinal abdominal bands? Enter your answer as a numerical value to as many decimal points as necessary. For example, for an answer of 1/4 you should enter as your response 0.25, for 1/64 you should enter 0.015625, etc. Answer:

A researcher is studying genetic patterns in Drosophila melanogaster and is focusing on 3 specific phenotypes. The first is eye colour, with the phenotypes in question being red (wild) and brown. The gene responsible for these phenotypes is 'A' and has two alleles: A leads to red eyes and a leads to brown eyes. A is completely dominant to a.

Also of interest are genes B and C, each with two alleles (B and b; C and c). Genes B and C determine fly colouration. Allele B produces flies that are very dark brown, verging on black, whereas allele b produces flies that are much lighter brown. Alleles B and b are incompletely dominant, meaning an in-between dark brown-red phenotype is also possible.

Gene C is epistatic to gene B, meaning dominant allele C has to be present for gene B to be expressed at all. If a fly has genotype cc, then the B gene will not be expressed, regardless of genotype, and the flies end up with an almost orange colour.

Finally, gene D is associated with the banding colouration pattern on an fly's abdomen. This gene has three alleles: D, d, and i. Allele D codes for horizontal bands, allele d codes for longitudinal bands, and allele i codes for no bands at all. Allele i is recessive, but alleles D and d are co-dominant.

Imagine that, in an experimental context, a female fly was mated with a male. The female has the genotype AaBbCcDi, while the male has the genotype Aabbccdd. Knowing that all four genes in question are located on different chromosomes, approximately what proportion of the offspring are expected to be males with brown eyes that have the light brown body phenotype and only longitudinal abdominal bands?

Enter your answer as a numerical value to as many decimal points as necessary. For example, for an answer of 1/4 you should enter as your response 0.25, for 1/64 you should enter 0.015625, etc.

Answer:

A researcher is studying genetic patterns in Drosophila melanogaster and is focusing on 3 specific phenotypes. The first is eye colour, with the phenotypes in question being red (wild) and brown. The gene responsible for these phenotypes is 'A' and has two alleles: A leads to red eyes and a leads to brown eyes. A is completely dominant to a.

Also of interest are genes B and C, each with two alleles (B and b; C and c). Genes B and C determine fly colouration. Allele B produces flies that are very dark brown, verging on black, whereas allele b produces flies that are much lighter brown. Alleles B and b are incompletely dominant, meaning an in-between dark brown-red phenotype is also possible.

Gene C is epistatic to gene B, meaning dominant allele C has to be present for gene B to be expressed at all. If a fly has genotype cc, then the B gene will not be expressed, regardless of genotype, and the flies end up with an almost orange colour.

Finally, gene D is associated with the banding colouration pattern on an fly's abdomen. This gene has three alleles: D, d, and i. Allele D codes for horizontal bands, allele d codes for longitudinal bands, and allele i codes for no bands at all. Allele i is recessive, but alleles D and d are co-dominant.

Imagine that, in an experimental context, a female fly was mated with a male. The female has the genotype AaBbCcDi, while the male has the genotype Aabbccdd. Knowing that all four genes in question are located on different chromosomes, approximately what proportion of the offspring are expected to be males with brown eyes that have the light brown body phenotype and only longitudinal abdominal bands?

Enter your answer as a numerical value to as many decimal points as necessary. For example, for an answer of 1/4 you should enter as your response 0.25, for 1/64 you should enter 0.015625, etc.

Answer:

Added by Nicholas C.

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