GENETICS Can someone please help me undestand this question

GENETICS ! Can someone please help me undestand this question?!

The question and answer have both been provided but I need an EXPLANATION!

You found five T4 rll mutants that will not grow on E. coli K(). You mixed together all possible combinations of two mutants (as indicated in the following chart), added the mixtures to E. coli K(), and scored for the ability of the mixtures to grow and make plaques (indicated as a + in the chart).

How many genes were identified by this analysis?

Answer: There are two complementation groups and therefore 2 genes.

How do you know it was 2 genes??

Which mutants belong to the same complementation groups?

1,4 and 2,3,5

How is it thesee groups??

Solution

- A Complementation test is used to find out the mutations of two strains are on different genes or not. If they are on same gene a - ve complementation test would be resulted.

- In the above given complementation table, two different mutatant strains are combined in different cmbinations.

- In the above table it is evident that there are two complementation groups, one is mutant 1&4 and other belonging to 2,3,5. Because mutant 1 did not show any positive interaction with mutant 4. So, mutations were on the same gene in these mutants 1 and 4.

- So it was also evident there are two genes in order to get a positive complementation test.

- Mutants 1 and 4 belong to one group and 2,3,5 belong to one group as mutations were on same gene in mutant 1 and 4 and are on different genes in 2, 3, 5 thus resulting in positive test in the later scenario.