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Unformatted text preview: SEX LINKAGE: Female Male Parental cross #1 X Female Male F1: all red eyes X 3 1 3:1 segregation indicates a single gene is involved, but…. Male Male Female Female Although the Red eye phenotype segregates 3:1, males and females behave differently. All of the females are red-eyed, while half of the males are red-eyed and half are white-eyed. With Mendel’s pea plants, it didn’t matter which parent an allele came from. Is that the case here? These previous results were obtained by crossing a red-eyed female with a white eyed male. What happens when the reciprocal cross (a white-eyed female with a red-eyed male) is done? Parental cross #2 These results are different from Cross #1! Female Male X 1/2 red-eyed all female F1: X 1/2 white-eyed all male F2: Female Male Male Female 1 1 1 1 These results are different from Cross #1! Calvin Bridges, an undergraduate in T. H. Morgan’s lab proposed that the gene responsible for the white eye color is on the X chromosome. Drosophila nomenclature: genes are named after the mutant phenotype: the white eye gene alleles are designated by one to three letters and are italicized: w + = wild type (red eyes) (plus sign indicates wild type)...
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This note was uploaded on 04/21/2010 for the course BIO 89329 taught by Professor Hollingsworth during the Spring '10 term at SUNY Stony Brook.
- Spring '10