leu- bacteria are mixed in a flask with leu+ bacteria, and soon all bacteria are leu+. However, if the leu- cells are on one side of a U-tube and the leu+ cells are on the other, the leu- cells do not become prototrophic. This suggests
Two different strains of a mutant phage infect a single bacterium. One phage strain is d- and the other is e-. Some of the progeny phages are genotype d+e+, and some are d-e-. What genetic phenomenon does this demonstrate?
Two different strains of a mutant phage infect a single bacterium. One phage strain is d-e+ and the other is d+e-. The coinfected phages produce the wild-type phenotype in the bacterium: one phage supplies the wild-type gene product from a d+ allele, and the other supplies the wild-type gene product from the e+ allele. What genetic phenomenon does this demonstrate?
You perform interrupted-mating experiments on three Hfr strains (A, B, and C). Genes are transferred (from last to first) in the following order from each strain: strain A, thi-his-gal-lac-pro; strain B, azi-leu-thr-thi-his; strain C, lac-gal-his-thi-thr. How are the F factors in these strains oriented?
A bacterium of genotype a+b+c+d+ is the donor in a cotransformation mapping. The recipient is a-b-c-d-. Data from the transformed cells are shown below. What is the order of the genes?
(a+ and b+ 2)
(a+ and c+ 0)
(a+ and d+ 5)
(b+ and c+ 5)
(b+ and d+ 0)
(c+ and d+ 0)
c b a d
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