Chapter 6, Problem 33P

From a cross between e f g and e f g strains of Neurospora, recombination between these linked genes resulted in a few octads containing the following ordered set of spores:

e⁺ f⁺ g⁺

e⁺ f⁺ g⁺

e⁺ f^- g⁺

e⁺ f^- g⁺

e^- f^- g^-

e^- f^- g^-

e^- f^- g^-

e^- f^- g^-

a. Where was recombination initiated?

b. Did crossing-over occur between genes e and g? Explain.

c. Why do you end up with 2 f+:6 f− but 4 e+: 4 e− and 4g+: 4g−?

d. Could you characterize these unusual octads as MI or MII for any of the three genes involved? Explain.