Six bands in a salivary-gland chromosome of Drosophila are shown in the followin
ID: 62888 • Letter: S
Question
Six bands in a salivary-gland chromosome of Drosophila are shown in the following illustration, along with the extent of five deletions (Del 1 to Del 5):
Recessive alleles a, b, c, d, e, and f are known to be in the region, but their order is unknown. When the deletions are combined with each allele, the following results are obtained:
a
b
c
d
e
f
Del 1
-
-
-
+
+
+
Del 2
-
+
-
+
+
+
Del 3
-
+
-
+
-
+
Del 4
+
+
-
-
-
+
Del 5
+
+
+
-
-
-
In this table, the minus sign means that the deletion is missing the corresponding wild-type allele (the deletion uncovers the recessive), and a plus sign means that the corresponding wild-type allele is still present. Use these data to infer which salivary band contains each gene.
a
b
c
d
e
f
Del 1
-
-
-
+
+
+
Del 2
-
+
-
+
+
+
Del 3
-
+
-
+
-
+
Del 4
+
+
-
-
-
+
Del 5
+
+
+
-
-
-
Explanation / Answer
Band 2 contains de
Band 3 contains f
Band 4 contains b
Band 5 contains a
Band 6 contains c