Practice question

Tetratype ascus includes two parental and two recombinant spores, showing four spore genotypes where parental types represented once each plus recombinants once each, total four spores representing crossover outcome from single exchange event. Origin single crossover involving two chromatids out of four generates half recombinant chromatids half parental chromatids within ascus. TT frequency increases with distance and dominates at intermediate distances around 20-30 cM, then declines. Formula uses half TT plus NPD over total to compute recombination because half chromatids in TT are recombinant chromatids counted toward RF.