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

1
Day 1 You set up a cross between WT males
and dpy17unc32 hermaphrodites (Po).
X
Representation of chromosome III
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 werent actually
setting up any crosses at this stageyou 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
F2 progeny from F1 without a recombination event
(non-recombinant progeny)


u32
d17
Genotype


u32
d17
WT
Phenotype
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 markersthats not very high. Also Think
about what the genotypes of your WT F2 worms that
youre 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?