In a strain of bacteria, all organisms are usually killed when a given amount of streptomycin is introduced into the growth medium.
Mutations arise that lead to resistance to streptomycin.
Given a sensitive strain, outline an experimental procedure by which resistant strains of the two types might be obtained. Frame shift mutations occur when bacteria are supplied with proflavine dyes. These intercalate between base pairs and induce errors in replication leading to the insertion or deletion of single bases. Taking a single frame shift mutant and exposing it to a second round of proflavine mutagenesis leads to recovery of additional mutations. Some of these are doubly mutant in the same gene.