Genotypes: The genotypes of the given phenotypes are:
• wings = dsr+, dsr (disrupted wings)
• body = sp+, sp (speck body)
• eyes = cn+, cn (cinnabar eyes)
Part A and B. Parent Generation:
Female = dsr sp cn+
Male = dsr+ sp+ cn
Assume that a female fly that has disrupted wings (dsr) and a speck body (sp) is mated to a male that has cinnabar eyes (cn).
Phenotypically wild-type F1 female progeny were mated to males that had speck bodies, disrupted wings and cinnabar eyes, and the following progeny were observed.
|Phenotype||Number of offspring|
|disrupted wings, speck body||241|
|disrupted wings, cinnabar eyes||25|
|speck body, cinnabar eyes||46|
|disrupted wings, speck body, cinnabar eyes||117|
Part A. From this information, determine which gene is in the middle.
Part B. With respect to the three genes mentioned in the problem, what are the genotypes of the parents used in making the phenotypically wild-type F1 heterozygote?
a) sp dsr cn / sp dsr cn and sp+ dsr+ cn+ / sp+ dsr+ cn+
b) sp dsr cn+ / sp dsr cn+ and sp+ dsr+ cn+ / sp+ dsr+ cn+
c) sp dsr+ cn / sp dsr+ cn and sp+ dsr+ cn / sp+ dsr+ cn
d) sp dsr cn+ / sp dsr cn+ and sp+ dsr+ cn / sp+ dsr+ cn
Part C. What is the map distance between sp and dsr? Express your answer to the nearest whole number.
Part D. What is the map distance between dsr and cn? Express your answer to the nearest whole number.