Cross #1: P: Homozygous scarlet-eyed males F₁ Fs Homozygous brown-eyed females X 1072 Wild-type (red-eyed) males and females F₁ males x F₁ females 2684 wild-type males and females 891 scarlet-eyed males and females 887 brown-eyed males and females 298 white-eyed males and females
You are conducting independent research for your Honors Thesis in a Drosophila research lab. One of the graduate student researchers has provided you with two mutant strains of Drosophila. One has scarlet eyes, and the other has brown eyes. You cross homozygous scarlet-eyed male Drosophila with female flies homozygous for the brown-eye color allele, and all of the male and female F1 flies have wild-type eyes. Crosses involving F1 males x F1 females yield the results shown in the image attached. You know the traits involved are autosomal, and that reciprocal parental crosses produce similar results.
Another undergraduate researcher in your lab is studying mutations affecting the wings of Drosophila melanogaster. She has identified two mutant
- bent wings (be), which are recessive to the wild-type straight wings (be+), and
- apterous (ap) mutants (which are wingless). The apallele is recessive to the wild-type allele (ap+), which allows wings to develop.
If a homozygous bent-winged fly (which possesses the normal allele of apterous) is crossed with a homozygous wingless fly (which possesses the normal allele of bent wings), what phenotypic ratio would you expect to observe in the F2 generation of this cross?
a) Please indicate the ratio, including the genotypes and phenotypes of all phenotypic classes.
- Phenotype: Genotype(s) corresponding to this phenotype
- Phenotypic ratio: (Be sure to NAME the classes in the ratio).
B) Please NAME and DEFINE the type of gene interaction illustrated in this example. Please explain how this definition specifically applies to this cross.
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