An experimenter is studying a gene that codes for a very small polypeptide phe-his-gly-cys-gly. He treated the cells with different mutagens with the following results to the protein:

• Normal: phe-his-gly-cys-gly
• Treatment #1: phe-his-gly-cys
• Treatment #2: ser-his-gly-cys-gly
• Treatment #3: phe-his-arg-val-trp

For each treatment, describe the exact mutagenic event (e.g. transition, transversion, frameshift, etc.), the most likely codon sequence, and the type of mutagen used.