Day 1: You set up a cross between WT males and dpy17unc32 hermaphrodites (“Po”).

1. + + d17 u32 + + d17 u32 + + + + d17 d17 u32 u32 + + d17 + + + d17 u32 + u32 d17 u32 Day 1: You set up a cross between WT males and dpy17unc32 hermaphrodites (“Po”). Representation of chromosome III: X Day 5: You singled 4 coming out of these crosses which all had the same genotype and phenotype (“F1”). Hermaphrodites have both egg and sperm, so they fertilize themselves. In this case, both egg and sperm have identical genotypes, so when the hermaphrodite fertilizes its own egg, this is what the self-mating looks like (but you must note that you weren’t actually setting up any crosses at this stage—you were letting the single hermaphrodites “self”). X Day 9: You should single up to 4 each of the following phenotypes: WT, dpy17unc32. And if you can find any of these rare events, 4 of dpy17 (nonunc) and unc32 (nondpy) (“F2”). The rare dpy-nonuncs and unc-nondpys are from a recombination event in the germline of the F1 worm (egg or sperm): X F1: (for example: egg) (recombinant egg) (non-recombinant sperm)

2. + + d17 u32 + + d17 u32 d17 + d17 + + u32 + u32 + + d17 u32 F2 progeny from F1 without a recombination event (non-recombinant progeny): + + d17 u32 Genotype: + + d17 u32 Phenotype: WT WT dpy17unc32 F2 progeny from F1 with a recombination event (recombinant progeny): Genotype: Phenotype: WT unc32 (nondpy) WT dpy17 (nonunc) You could see all of the 7 possible combinations on the SAME F1 plate (you could have WT, dpy17unc32, dpy17 only, and unc32 only worms all on one plate)! The recombinant dpy17 and unc32 progeny are so rare because dpy17 and unc32 are 2 map units apart. This means that there is a 2% chance that recombination will occur between these markers—that’s not very high. Also: Think about what the genotypes of your WT F2 worms that you’re singling could be. There are 4 different possibilities! This will be important for looking at your F3 progeny on Day 14.

3. Day 14: Examine F3 progeny. When you are thinking about the different phenotypes you are seeing in the F3 progeny, you must consider the genotype of your F2. • Look at your WT F2 plates. Consider the 4 possible genotypes the F2 could have been by looking at the types of F3 worms on the plate (do this for all of your F2 plates independently). • Do you see any dpy17unc32 F3s? What kind of genotype(s) could the F2 have been in this case? • Do you see any dpy17 nonunc F3s? What kind of genotype(s) could the F2 have been? • Do you see any unc32 nondpy F3s? What kind of genotype(s) could the F2 have been? • Combining your above results, what is the genotype of your F2? • Look at your dpy17unc32 plates (do this for all of your F2 plates independently). • Are all of the F3 worms dpy17unc32? Why or why not? • Look at your dpy17 nonunc plates (do this for all of your F2 plates independently). • Are all of the F3s dpy? Why or why not? • Are there any dpy17unc32 F3s? If yes, why do you think this is? • Look at your unc32 nondpy plates (do this for all of your F2 plates independently). • Are all of the F3s unc32? Why or why not? • Are there any dpy17unc32 F3s? If yes, why do you think this is?