Linked genes and recombination Original Scenario-Based Download PDF

Questions

1. 1.

   During an expedition into an uncharted crystal cavern, biologists study a rare luminescent beetle whose traits for shell texture (smooth, S, dominant to rough, s) and bioluminescent glow (emerald, E, dominant to amber, e) are linked on the same autosome. A dihybrid female carrying alleles in the coupling (cis) configuration (SE/se) is test-crossed with a homozygous recessive male (se/se). The resulting 1,000 progeny consist of 425 smooth emerald, 415 rough amber, 82 smooth amber, and 78 rough emerald individuals. Based on these data, what is the recombination frequency between these two loci, and what does this demonstrate about their linkage?

   • A) The recombination frequency is 32%, demonstrating that these loci sort independently according to Mendel's second law.
   • B) The recombination frequency is 16%, demonstrating that the loci are linked on the same chromosome at a genetic map distance of 16 centimorgans.
   • C) The recombination frequency is 84%, demonstrating that crossing over separates the parental allele combinations in the vast majority of gametes.
   • D) The recombination frequency is 8%, demonstrating that gene conversion rather than reciprocal recombination produced the minor phenotypic classes.