In Drosophila, recessive mutations in the fruitless gene (fru) result in males courting other males; and recessive mutations in the Antennapedia gene (
a. What
b. Your cross results in the following phenotypic proportions:
Legs on head, normal courting behaviour
Normal head, abnormal courting behaviour
Legs on head, abnormal courting behaviour
Normal head, normal courting behaviour
Provide a genetic explanation for these result and describe a test for your hypothesis.
c. Provide a molecular explanation for the reason your new
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Genetic Analysis: An Integrated Approach (3rd Edition)
- In Drosophila, Lyra (Ly) and stubble (Sb) are dominant mutations located at locus 40 and 58, on chromosome 3. A recessive mutation with bright eyes was discovered and shown also to be on chromosome 3. A map was obtained by crossing a female who was heterozygous for all three mutations to a male homozygous for the bright red mutation (temporarily will be called br). The following data were obtained. Ly Sb br 404 + + br 2 Ly + br 75 + Sb + 59 Ly + + 18 + Sb br 16 Ly Sb + 4 + + + 422 Diagram the cross and determine the location of the bright red mutation on chromosome 3arrow_forwardThe locations of six deletions have been mapped to a Drosophila chromosome, as shown in the following deletion map. Recessive mutations a, b, c, d, e, and f are known to be located in the same region as the deletions, but the order of the mutations on the chromosome is not known.arrow_forwardIn Drosophila, one of the genes controlling wing length is located on the X chromosome. A recessive mutant allele of this gene makes the wings miniature—hence, its symbol m; the wild-type allele of this gene, m_, makes the wings long. One of the genes controlling eye color is located on an autosome. A recessive mutant allele of this gene makes the eyes brown—hence, its symbol bw; the wildtype allele of this gene, bw_, makes the eyes red. Miniature-winged, red-eyed females from one true-breeding strain were crossed to normal-winged, brown-eyed males from another true-breeding strain. 1. Predict the phenotypes of the F1 flies. 2. If these flies are intercrossed with one another, what phenotypes will appear in the F2, and in what proportions?arrow_forward
- A male Drosophila with wild-type phenotype is discovered to have only seven chromosomes, whereas normally 2n = 8. Close examination reveals that one member of chromosome IV (the smallest chromosome) is attached to (translocated to) the end of chromosome II. If this male mates with a female with a normal chromosome composition who is homozygous for the recessive chromosome IV mutation eyeless (genotype = ee), what would be the eye genotypes, eye phenotypes, and total number of chromosomes in all potential offspring if the male is homozygous for the wild-type allele (EE)? put a table for punnet squarearrow_forwardA male Drosophila with wild-type phenotype is discovered to have only seven chromosomes, whereas normally 2n = 8. Close examination reveals that one member of chromosome IV (the smallest chromosome) is attached to (translocated to) the end of chromosome II. If this male mates with a female with a normal chromosome composition who is homozygous for the recessive chromosome IV mutation eyeless (genotype = ee), what would be the eye genotypes, eye phenotypes, and total number of chromosomes in all potential offspring if the male is homozygous for the wild-type allele (EE)?arrow_forwardOne of the X chromosomes in a particular Drosophila female had a normal order of genes but carried recessive alleles of the genes for yellow body color (y), vermilion eye color (v), and forked bristles (f), as well as the dominant X-linked Bar eye mutation (B). Her other X chromosome carried the wild-type alleles of all four genes, but the region including y+, v+, and f+ (but not B+) was inverted with respect to the normal order of genes. This female was crossed to a wild- type male in the cross diagrammed her. The cross produced the following male offspring:* table in figure a. Why are there no male offspring with the allele combinations y v f+, v+ v+ f, y v+ f+, or y+ v f (regardless of the allele of the Bar eye gene)?b. What kinds of crossovers produced the y v f b+ and v+ y+ f+ B offspring? Can you determine any genetic distances from these classed of progeny?c. What kinds of crossovers produced the y+ v f+ B+ and y v+ f B offspring?arrow_forward
- In Drosophila, Dichaete (D) is a mutation on chromosome III with a dominant effect on wing shape. It is lethal when homozygous. The genes ebony body (e) and pink eye (p) are recessive mutations on chromosome III. Flies from a Dichaete stock were crossed to homozygous ebony, pink flies, and the F1 progeny, with a Dichaete phenotype, were backcrossed to the ebony, pink homozygotes. Using the results of this backcross shown in the table, (b) What is the sequence and inter locus distance between these three genes?arrow_forwardOne of the X chromosomes in a particular Drosophila female had a normal order of genes but carried recessive alleles of the genes for yellow body color (y), vermilion eye color (v), and forked bristles (f), as well as the dominant X-linked Bar eye mutation (B). Her other X chromosome carried the wild-type alleles of all four genes, but the region including y+, v+, and f+ (but not B+) was inverted with respect to the normal order of genes. This female was crossed to a wild-type male in the cross diagrammed her. The cross produced the following male offspring: Y v f B 48 y+ v+ f+ B+ 45 y v f B+ 11 y+ v+ f+ B 8 y v f B 1 y+ v+ f+ B+ 1 a. Why are there no male offspring with the allele combinations y v f+, v+ v+ f, y v+ f+, or y+ v f (regardless of the allele of the Bar eye gene)? b.What kinds of crossovers produced the y v f b+ and v+ y+ f+ B offspring? Can you determine any genetic distances from these classed of progeny? c. What kinds of crossovers produced the…arrow_forwardThe mutations called bobbed in Drosophila result from variable reductions (deletions) in the number of amplified genes coding for rRNA. Researchers trying to maintain bobbed stocks have often documented their tendency to revert to wild type in successive generations. Propose a mechanism based on meiotic recombination which could account for this reversion phenomenon. Why would wild-type flies become more prevalent in Drosophila cultures?arrow_forward
- In drosophila, a recessive mutation (m-) of a maternal effect gene results in an abnormalphenotype wherein homozygous (m-m-) females produce eggs that cannot support embryonicdevelopment. Homozygous (m-m-) males, however, can still produce viable sperm. Using m+ todenote a normal gene, determine the genotypes and phenotypes of the F1s produce by a crossbetween a heterozygous female and a recessive male. From the offspring, backcross the recessivefemale with the paternal strain. What are the genotypes and phenotypes of the F2s?arrow_forwardYou are interested in studying position effect variegation in Drosophila using the chromosome depicted below: Deactivation of the w+ gene gives a white eye phenotype and deactivation of the rst+ gene gives a rough eye phenotype; the normal phenotypes are red and smooth. Because the rst+ and w+ genes have now been placed close to a heterochromatic domain, some sections (or sectors) of the eye display mutant phenotypes due to gene deactivation while others display the normal, wild type phenotype. Which phenotype would you not expect to see rst w Inverted X chromosome white smooth eye sectors white rough eye sectors red smooth eye sectors red rough eye sectorsarrow_forwardIn drosophila, a recessive mutation (m-) of a maternal effect gene results in an abnormal phenotype wherein homozygous (m-m-) females produce eggs that cannot support embryonic development. Homozygous (m-m-) males, however, can still produce viable sperm. Using m+ to denote a normal gene, determine the genotypes and phenotypes of the F1s produce by a cross between a heterozygous female and a recessive male. From the offspring, backcross the recessive female with the paternal strain. What are the genotypes and phenotypes of the F2s? Show COMPLETE cross for both cases. If m-m- females produce useless eggs, then how are m-m- produced?arrow_forward
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