In the fruit fly Drosophila melanogaster , the trait of black body is due to a g

Question

In the fruit fly Drosophila melanogaster, the trait of black body is due to a gene on chromosome 2 and black body b is recessive to wild type body b+. The trait of purple eyes is controlled by a gene that is also on chromosome 2 and purple eyes p is recessive to wild type eyes p+. A true-breeding wild type strain is crossed with a true breeding strain that has black bodies and purple eyes. The F1 generation is then testcrossed to the black body, purple eye strain and 500 progeny are produced as follows:

                        230 wild type for both body and eye

                        220 black body and purple eye

                        20 wild type body and purple eye

                        30 black body and wild type eye

What is the recombination frequency between the two genes?

Explanation / Answer

Recombination freequency (RF) = Total number of recombinants/ Total number of progeny * 100.

The recombinants are low in frequencies where as the parents are high in frequencies.

So, here 20 wild type body and purple eye and 30 black body and wild type eye are recombants, 230 wild type for both body and eye and 220 black body and purple eye are parental categories.

So, The RF = 20+30/20+30+230+220*100 = 50/500*100 = 10.

So, THE ANSWER IS 10%.

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