Question

Suppose a geneticist uses a three-point testcross to map three recessive, linked hummingbird wing-shape mutations called tn, f, and b, where tn is associated with thin wings, f is associated with flat wings, and b is associated with blunt wings. He first crosses homozygous blunt birds to homozygous thin, flat birds. Next, he testcrosses the F1 progeny to thin, flat, blunt birds. He obtained the results shown. Given this data, label the progeny phenotypic classes as either parental, single crossover (SCO), or double crossover (DCO) recombinant types. Each label may be used multiple times. Two classes have already been filled in. Phenotype Number Recombinant type blunt 783 Answer Bank thin, flat 803 parental DCO flat 161 sco thin, blunt 199 SCO thin 7 L 1 flat, blunt thin, flat, blunt SCO wild type 25

Answer 1

Phenotype Recombinant type Number 783 803 blunt thin, flat flat thin blunt Parental Parental sco 161 199 sco thin DCO 7 6 DCO flat, blunt thin, flat, blunt SCO wild type sco