Chapter 10, Problem 21P

In Drosophilia, seven partial deletion ( $1\text{to7}$) shown as gaps in the following diagram have been mapped on a chromosome. This region of the chromosome contains genes that express seven recessive mutant phenotypes, identified in the following table as a through g. A researcher wants to determine the location and the order of genes on the chromosome, so he sets up a series of crosses in which files homozygous for a partial deletion. The progeny are scored to determine whether they have the mutant phenotype (“m” in the table) or the $\text{wild-type}$ phenotype ( $\text{"+"}$). Use the partial deletion map and the table of progeny phenotypes to determine the order of genes on the chromosome.

			Mutation
Deletion	a	b	c	d	e	f	g
1	+	m	+	m	+	+	+
2	m	+	+	+	+	m	+
3	m	+	+	+	+	+	m
4	m	+	+	m	+	m	m
5	+	m	+	m	m	+	+
6	m	m	m	m	+	m	m
7	m	+	+	+	+	+	+