BIOL 142 Lecture Notes - Lecture 15: Bacterial Conjugation, Pilus, Hfr Cell
13 Mar 2018
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11:56 am: an organism that has lost its ability to synthesize its own histidine is called a(an): We know what mutation an organism has but what it needs in its medium to grown. Experiment: a prototrophic strain was produced by inoculating medium with the two auxotrophic e. coli strains. Strain a and b can synthesize and not synthesize different things. Mix a and b in complete medium; incubate overnight. Results: after co-culturing them, they can both grow on minimal media. Possibility 1: spontaneous mutations arouse simultaneously at multiple independent locations leading to wildtype cells. Possibility 2: genetic exchange and recombination occurred between the two mutant strains. The odds of strain a and b reverting multiple mutations to wildtype is really unlikely. Conjugation involves a unidirectional transfer of genetic information. F+ (fertility) cells: donate a dna plasmid to recipient cells. Modified experiment: to test the requirement of direct cell contact for the unidirectional transfer of chromosomal material.
