Three recessive genes on chromosome 2 of Drosophila melanogaster are: welt , ves
ID: 169415 • Letter: T
Question
Three recessive genes on chromosome 2 of Drosophila melanogaster are: welt , vestigial , and black . The numbers of phenotypes from a trihybrid test cross are shown below: Wild type 719 welt ,vestigial ,black 667 welt 148 vestigial ,black 132 black 2188 welt ,vestigial 2107 vestigial 753 welt ,black 726 What is the gene order and map distance between the three genes and what is the percent interference? Please type the answer. Including the full explanation of the question and the solution with details. Three recessive genes on chromosome 2 of Drosophila melanogaster are: welt , vestigial , and black . The numbers of phenotypes from a trihybrid test cross are shown below: Wild type 719 welt ,vestigial ,black 667 welt 148 vestigial ,black 132 black 2188 welt ,vestigial 2107 vestigial 753 welt ,black 726 What is the gene order and map distance between the three genes and what is the percent interference? Please type the answer. Including the full explanation of the question and the solution with details. Three recessive genes on chromosome 2 of Drosophila melanogaster are: welt , vestigial , and black . The numbers of phenotypes from a trihybrid test cross are shown below: Wild type 719 welt ,vestigial ,black 667 welt 148 vestigial ,black 132 black 2188 welt ,vestigial 2107 vestigial 753 welt ,black 726 Wild type 719 welt ,vestigial ,black 667 welt 148 vestigial ,black 132 black 2188 welt ,vestigial 2107 vestigial 753 welt ,black 726 What is the gene order and map distance between the three genes and what is the percent interference? Please type the answer. Including the full explanation of the question and the solution with details.Explanation / Answer
Take welt as w, vestigal as v and black as b
w,v,b = 719
w+,v+,b+ = 669
w+,v,b = 148
w,v+,b+ = 132
w,v,b+ = 2188
w+,v+,b = 2107
w,v+,b = 753
w+,v,b+ = 726
Total = 7440
The parental input in the genotype is w+,s,b and w,s+,b+
In w and v loci ; w,v and w+,v+, there are 719+669+2188+ 2107 = 5683 recombinants
RF of w and v loci is 5683/7440*100 = 76.3%
In w and b loci ; w,b and w+,b+ , there are 719+669+753+726= 2867 recombinants
RF of w and b loci is 2867/7440*100 = 38.5%
In v and b loci ; v,b and v+,b+ there are 719+669+148+ 132 = 1668
RF of v and b loci is 1668/7440*100 = 22.4%
The RF value less than 50% indicates the nearness of the genes whereas here the RF value of w and v is more than 50% suggesting that the genes are located wide apart.
Thus b is between them-
I____________________I_________________________I
w 38.5m.u b 22.4 m.u v
Test cross - w+,v,b/w,v+,b+ and w,b,v/w,b,v
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