Can someone please help me solve this problem, I have posted this question twice
ID: 55279 • Letter: C
Question
Can someone please help me solve this problem, I have posted this question twice and prof, said it was still incorrect. Please can someone help me get the right answer??
Drosophila has four pairs of chromosomes: the sex chromosomes (XX in the females; XY in the males) and three pairs of autosomes. You are studying a new mutant strain with blue eyes. You wish to know if blue eye colour is a dominant mutation and on which chromosome the blue eye locus can be found. When you cross a purebreeding female blueeyed fly with vestigial wings and spineless bristles to a male fly with wild type eye colour, wings, and bristles, all of the F1 progeny are completely wild type. An F1 male is backcrossed to a triple mutant female, producing the following progeny (remember that there is no crossing over in Drosophila males):
Wild type eyes, wings, and bristles: 72 females, 69 males
Wild type eyes and bristles, vestigial: 83 females, 77 males
Wild type wings, blue eyes, spineless: 60 females, 65 males
Blue eyes, spineless, vestigial: 62 females, 58 males
1- Is the mutation dominant or recessive?Explain.
2-Since you know that the locus for vestigial wings is on chromosome 2 and the locus for spineless bristles is on chromosome 3, what chromosome carries the locus for blue eyes? Show your work, including the stepbystep reasoning you used to arrive at your answer.
3-When an F1 female is backcrossed to a triple mutant male, the following 1,000 progeny are produced:
Wild type eyes, wings, and bristles: 90 females, 89 males
Wild type eyes and bristles, vestigial: 83 females, 98 males
Wild type eyes and wings, spineless: 37 females, 35 males
Wild type wings and bristles, blue eyes: 36 females, 34 males
Wild type wings, blue eyes, spineless: 92 females, 88 males
Wild type eyes, spineless, vestigial: 34 females, 39 males
Wild type bristles, vestigial, blue eyes: 33 females, 37 males
Blue eyes, spineless, vestigial: 90 females, 85 males
4-Calculate the map distance between blue eye and any linked genes from the above progeny. Show your work
Explanation / Answer
2-Since you know that the locus for vestigial wings is on chromosome 2 and the locus for spineless bristles is on chromosome 3, what chromosome carries the locus for blue eyes? Show your work, including the stepbystep reasoning you used to arrive at your answer.
blue eyes- be- ,vestigial- v - spineless - s - x wild type be+ wings v+ bristles s+
heterozygous be - v + / be+ v - = 285 / 546 x 100 = 52 % RF (recombinant frequency) these two loci are not linked and are not on the same chromosome, both the loci have equal chance of getting expressed
heterozygous v + s - / v - s + = 285 / 546 x 100 =52 % RF (recombinant frequency) these two loci are not linked and are not on the same chromosome, both the loci have equal chance of getting expressed
Since there is no heterozygous expression ( no crossing over) between be + and s + / be - s - and both the loci are linked
therefore, locus for blue eyes present along with spineless bristles on chromosome 3
1- Is the mutation dominant or recessive?Explain.
Since equal number of progeny is expressed with the mutant allele (50% ie 1 : 1) And the parents are heterozygous for the mutant allele. The mutant allele should be recessive inheritance.
Note If Dominant allele then all the progeny will be expressed with wild type eye.
Would like to answer the second question next time.