Based on our discussion of the potential inaccuracy of mapping (see Figure , would you rev...

Based on our discussion of the potential inaccuracy of mapping (see Figure , would you revise your answer to Problem? If so, how?

FIGURE

(a) A double crossover is undetected because no rearrangement of alleles occurs. (b) The theoretical and actual percentage of recombinant chromatids versus map distance. The straight line shows the theoretical relationship if a direct correlation between recombination and map distance exists. The curved line is the actual relationship derived from studies of Drosophila, Neurospora, and Zea mays.

An organism of the genotype AaBbCc was testcrossed to a triply recessive organism (aabbcc). The genotypes of the progeny are presented in the following table.

(a) If these three genes were all assorting independently, how many genotypic and phenotypic classes would result in the offspring, and in what proportion, assuming simple dominance and recessiveness in each gene pair?

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(b) Answer part (a) again, assuming the three genes are so tightly linked on a single chromosome that no crossover gametes were recovered in the sample of offspring.

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(c) What can you conclude from the actual data about the location of the three genes in relation to one another?