Reference no: EM133561815
Question: The common fruit fly, Drosophila melanogaster, became a model organism in genetics due to the pioneering experiments of Thomas Hunt Morgan. In 1923, Bridges and Morgan published much of their data on genetic experiments in Carnegie Institution Publ. No. 327. Among the experiments they reported in this volume concerned two characteristics: wing position and scutellar hair. Normal (wild-type) flies fold their wings over their abdomens when at rest but flies with the mutant "dichaete" phenotype have wings that are raised and pointed outward when at rest (see the diagram below). Normal (wild-type) flies have no hairs on the scutellum (the most posterior segment of the thorax) but flies with the mutant "hairy" phenotype have hairs on the scutellum. Bridges and Morgan mated a dichaete (not hairy) female with a true-breeding hairy (not dichaete) male. In the progeny of this first cross, half of the flies (both male and female) were dichaete and none were hairy. They selected the dichaete females from their progeny and mated them with true-breeding hairy (not dichaete) males. In the progeny of this second cross, they observed the following phenotypic results: Wild type (neither dichaete nor hairy) 116 Dichaete (not hairy) 652 Hairy (not dichaete) 613 Dichaete, hairy 104
3. Is the mutant allele for Dichaete dominant or recessive? A. Dominant B. Recessive
4. Is the mutant allele for hairy dominant or recessive? A. Dominant B. Recessive
5. Using D and d to represent the alleles governing wing position, and H and h to represent the alleles governing scutellar hair, what is the genotype of the original Dichaete female Bridges and Morgan used in the first cross? (Remember uppercase letters represent dominant alleles and lowercase letters recessive alleles.)
A. DDHH B. DdHH D. DDHh E. DdHh G. DDhh H. Ddhh C. ddHH F. ddHh I. ddhh
6. Using D and d to represent the alleles governing wing position, and H and h to represent the alleles governing scutellar hair, what is the genotype of the original hairy male Bridges and Morgan used in the first cross? (Remember uppercase letters represent dominant alleles and lowercase letters recessive alleles.)