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Modern Genetic Analysis Chapter 7. Gene Mutations
Solved Problem

4. | A mutant of E. coli is highly resistant to mutagenesis by a variety of agents, including ultraviolet light, aflatoxin B1, and benzo(a)pyrene. Explain one possible cause of this mutant phenotype. See answer

| Solution The mutant might lack the SOS system and perhaps carries a defect in the umuC gene. Such strains would not be able to bypass replication-blocking lesions of the type caused by the three mutagens listed. Without the processing of premutational lesions, mutations would not be recovered in viable cells. See question

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