Microbiology Quiz
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MICROBIAL GENETICS AND GENE REGULATION
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A researcher has three unknown E. coli donor strains (1, 2, 3) and an F⁻ recipient (his⁻ leu⁻ trp⁻). After separate matings, the following results are observed: Mating with Strain 1 yields a high frequency of trp⁺ recombinants, and nearly all recipient cells become donor cells. Mating with Strain 2 yields a high frequency of his⁺ recombinants but a very low frequency of trp⁺ recombinants, and recipients remain F⁻. Mating with Strain 3 yields a high frequency of conversion to donor status but produces no chromosomal recombinants. What are the likely identities of the donor strains?
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