Question

After treating cells with a chemical mutagen, several mutants are isolated. One carries arginine at a site in the protein that normally codes serine. After treating the mutants again, isolates now carry methionine at the site of the original serine. The next round of mutation yields a leucine site. Assuming that all mutations involve single-nucleotide changes, deduce the codons that are used for serine, arginine, methionine, and leucine at the affected site. Would you expect to be able to isolate a valine-to-threonine mutant in one step?

Answer 1