In Drosophila melanogaster, the allele for red eyes is dominant over the allele for purple eyes, and the allele for a gray body is dominant over the allele for a black body. A testcross was done to check for genetic linkage between the genes for these traits. The results for the offspring are listed as follows: 478 flies with red eyes and a gray body
27 flies with red eyes and a black body
462 flies with purple eyes and a black body
33 flies with purple eyes and a gray body
Which of the choices below best represents the map distance between the genes for these two traits?

Question

Quizplus · Accepted Answer

The map distance between the genes for these two traits can be calculated using the number of recombinant offspring (those with non-parental type combinations) divided by the total number of offspring, multiplied by 100 to get a percentage, which is equivalent to map units. In this case, the recombinant offspring are those with red eyes and a black body (27) plus those with purple eyes and a gray body (33), giving a total of 60 recombinant offspring. The total number of offspring is 478 + 27 + 462 + 33 = 1000. Therefore, the map distance is (60/1000) * 100 = 6.0 map units.

In Drosophila Melanogaster, the Allele for Red Eyes Is Dominant