1. The problem statement, all variables and given/known data You decide to revert an iob- mutant to wild type (IOB+) using different mutagens and find the following reversion rates for each mutagen tested: 2-amino purine - 98% 5-bromouracil - 95% Nitrous acid - 94% Proflavin - 2% Spontaneous - 4% 1. What is the most likely molecular basis of the original iob- mutation? 2. What does the reversion test data suggest about the most prominent mechanism of spontaneous mutations in this organism? 3. You decide to isolate deletion mutations in the IOB gene. Suggest a genetic screen that would enrich for deletion mutations in this gene over other types of loss-of-function mutations. 4. Suggest two genetic tests that would show you have indeed identified iob deletion mutants. 2. Relevant equations 3. The attempt at a solution 1. I assumed that since bromouracil, nitrous acid, and aminopurine all cause transition mutations, the original mutation is likely a transition - but i wasn't sure if that's what they meant by molecular basis? 2. Since I'm assuming the original mutation was a transition, and the rate of spontaneous revertants is very low, I was thinking I'd suggest that the most prominent mechanism of mutations in this organism is not transition mutations - but again i wasn't sure if i was answering what the question was asking 3. I'm at a loss here - any ideas?! *** I was thinking possibly using a mutagen that is known to cause deletions (but I couldn't seem to find any) or one that causes both deletions and insertions and then screening for insertions by the methods described in 4, but I couldn't seem to find a mutagen like that either. HEEEELP! 4. If I could answer number 3, then i was thinking i could use PCR analysis or comparative genomic hybridization, does that make sense? Your opinions would be much appreciated!