6. A space probe discovers a planet inhabited by creatures who reproduce with the same hereditary patterns as those in humans. Three phenotypic characters are height (T = tall, t = dwarf), hearing appendages (A = antennae, a = no antennae), and nose morphology (S = upturned snout, s = downturned snout). Since the creatures were not "intelligent" Earth scientists were able to do some controlled breeding experiments, using various heterozygotes in testcrosses. For a tall heterozygote with antennae, the offspring were tall-antennae, 46; dwarf-antennae 7; dwarf-no antennae 42; tall-no antennae 5. For a heterozygote with antennae and an upturned snout, the offspring were antennae-upturned snout 47; antennae-downturned snout, 2; no antennae-downturned snout, 48: no antennae-upturned snout 3. Calculate the recombination frequencies for both experiments.
Determine the recombination frequency for the genes controlling Tallness and Antennae:
46 tall-antennae
= 46%
expected
42 dwarf-no antennae
= 42%
expected
7 dwarf-antennae
= 7%
recombinant
5 tall-no antennae
= 5%
recombinant
Total = 100
Therefore this recombination frequency between genes T and A is 12%
Determine the recombination frequency for the genes controlling Antennae and Snout:
47 antennae-upturned snout
= 47%
expected
48 no antennae-downturned snout
= 48%
expected
2 antennae-downturned snout
= 2%
recombinant
3 no antennae-upturned snout
= 3%
recombinant
Total = 100
Therefore this recombination frequency between genes A and S is 5%