Question

A complementation test was conducted with 7 different mutant organisms (numbered 1-7), all having the same mutant phenotype. All 7 mutants were crossed to each other and the results are below. Using the chart of the complementation test, answer the following questions. (6 points)

	1	2	3	4	5	6	7
1	-	+	+	-	-	+	+
2	+	-	+	+	+	+	-
3	+	+	-	+	+	+	+
4	-	+	+	-	-	+	+
5	-	+	+	-	-	+	+
6	+	+	+	+	+	-	+
7	+	-	+	+	+	+	-

A.) How many different genes are present in this set of 7 mutants?

B.) Is this mutation dominant or recessive in nature?

Please show work!! Im especially having trouble answering B.

Answer 1

(A)
Assumption:

'-' means allelic to each other
'+' means not allelic to each other

From the given table, we can group the seven given mutants into four independent complementation groups.
They are,
a. 1 = 4 = 5
b. 2 = 7
c. 3
d. 6
So, there are four different mutants.

(B)
The given information is not enough to comment on whether the listed four mutant groups are recessive or dominant.
But, we can predict their nature.

For example,
If we assume that all the given mutants are homozygous for their respective genotypes, 1, 4 and 5 could be recessive.
Six and three could be dominant mutants
Two and seven could be recessive mutants