Question

You are trying to map five new mutations in the rII locus in phage. You only know that mutation 1 is in gene A, and mutation 2 is in gene B. Given the following complementation testing results, which best represents the distribution of the mutations into the two complementation groups?

Select one:

a. Group A: 1, 3, 5; Group B: 2, 4

b. There is not enough information provided to answer this question.

c. Group A: 1, 2, 4; Group B: 3, 5

d. Group A: 1, 2, 3; Group B: 4, 5

Answer 1

First option

In the question, it is given that the five mutations are forming a complementation group. It means these mutations will be on different groups or different complementation groups or will be present on different genes.

If the mutations are present on different genes, then they are complementing each other and if the mutation are not present on different genes, or if they are present on same genes, they are not complementing each other and we do not get wild phenotype in the progeny.

So the first option is correct because first mutation is present on gene A and second mutation is present on gene B as per the question and this option is indicating the same thing.

Second option and third and fourth are incorrect because as per 3rd and 4th, both the mutations are present in first group.

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