Question: You’ve isolated a collection of X-linked, recessive lethal mutations of Drosophila. Such mutation…

You’ve isolated a collection of X-linked, recessive lethal
mutations of Drosophila. Such mutations are lethal when
homozygous or hemizygous. You examine the polytene chromosomes of
your mutants and recognize that four of them contain deletions
(deficiencies) of defined portions of the X chromosome. You name
these deletion mutations Df1, Df2, Df3, Df4.

In your misc. collection of Drosophila strains, you
have nine X-linked recessive mutations that affect various aspects
of the fly’s phenotype (wing shape, eye color, bristle morphology,
etc.). You know that these mutations are located on the X
chromosome, because they show sex-linked inheritance. These nine
mutations are named v1 through v9, where v stands
for “visible phenotype.”

You cross each of the four deletion-containing strains with each
of the nine visible-containing strains and test whether the
deletions “uncover” the visible allele (i.e. whether the recessive
visible alleles exhibit pseudodominance among the progeny). Your
data are shown in the table; in each case, a “+” indicates that the
Df/v heterozygote is normal. A number indicates that the
heterozygote exhibits the phenotype of the visible allele. (See
chart)

1. What is the order of the genes that are represented by
visible mutant strains v1, v2, v3, v5, v6, v7 and
v8? (i.e. all except v4 and v9)

2. You notice that mutants v3 and v5 both have
the same visible phenotype (curled wings). Is it likely that these
two mutations affect the same gene?

3. You notice that, although mutants v2 and v9
have slightly differing phenotypes (pink eyes and ruby eyes), they
are both located in the same region of the X chromosome. Is it
possible that these two mutations affect the same gene?

4. If you wanted to test whether v2 and v9
?were alleles of the same gene, what kind of test would
you do? (One word answer)

5. From what you know so far, what visible mutant phenotypes
would a Df2/Df3 female show? (v1-8, or none)

6. You isolated a new deletion mutation, Df5, and found
that it only uncovers the visible phenotypes of v4 and
v5. What is your revised gene order for all genes
represented by mutant strains v1 through v8 (i.e.
all except v9)?