Given the prevalence of cockroaches in Shoemaker, some graduate students decide

Question

Given the prevalence of cockroaches in Shoemaker, some graduate students decide to pursue some genetics experiments with them. They find that the genes for antennae length, body color, and wing shape are all located on the same chromosome. Short antennae (sa), red body color (rd), and curly wings (cw) are the mutant forms of the wild type traits long antennae, brown body, and straight wings, respectively.

After during a series of well-controlled crosses, the graduate students deduce that the distance between cw and sa is 16.6 m.u., the distance between rd and cw is 28.2 m.u., and the distance between rd and sa is 42.9 m.u.

Question: If a total of 1500 offspring were obtained from your cross, determine the number of offspring that you would expect to obtain that represent a single crossover event between sa and cw if interference does not occur. Enter your answer as a whole number (rounded to the nearest integer).

Hint: make sure you use the r = SCO + DCO formula

Explanation / Answer

Answer:

The number of offspring that you would expect to obtain that represent a single crossover event between sa and cw = 320

Explanation:

Based on the information, the order of genes as follows.

rd---------28.2----------cw---------16.6------------sa

The double crossover frequency = 28.2% * 16.6% = 0.047 = 4.7%

The single crossover frequency between cw & sa = 16.6 + 4.7 = 21.3%

The number of offspring that you would expect to obtain that represent a single crossover event between sa and cw = 21.3 % * 1500 = 320

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