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pitt.edu the nematode Caenorhabditis elegans, mutations in the gene dpy-16 resul

ID: 195489 • Letter: P

Question

pitt.edu the nematode Caenorhabditis elegans, mutations in the gene dpy-16 result in a short body bumps on the body surface (relative to the normal smooth body surface). Since bli-7 was elative to the normal wild-type body), while mutations in a newly-discovered gene, bli-7, result iscovered using a forward genetics approach, its location in the C. elegans genome is unknown. You need to generate a strain of worms that are homozygous miutant for both 16 and bli-7 for a project. You cross homozygous mutant dpy-16 worms (short body, smooth surface) with homozygous mutant bli-7 worms (normal body, bumpy surface). Fi progeny are all wild-type in appearance (normal body, smooth surface). Are the mutant alleles dominant or recessive? (0.5 pts) dpy-16 mutant allele is bli-7 mutant allele is You cross your Fi heterozygotes with other F, heterozygotes to generate your double mutant. Assuming the genes are assorting independently, how many F: progeny should you examine to be reasonably sure of recovering one double mutant? Use a 95% confidence interval. (1 pt) 2. 14 MacBook Pro

Explanation / Answer

mutant dpy 16 short body dd

mutant bli -7   Bumbs on surface bb

                          Short body smooth surface dd BB X Normal body bumby surface DD bb

                                                     Gametes   Bd          X     bD

                                                 F1                         BbDd      All are wild type Normal body smooth surface

So, the mutation are recessive.

mutant dpy 16 allele recessive - dd

mutant bli -7   allele recessive - bb

B                                                      BbDd       X               BbDd     

      This is dihybrid cross and assort independently. So, it ratio 9:3:3:1

1/16 possibilites we get double mutant.