This is a question from my exam -
48. An ambitious intern discovered a 100-kb circular plasmid in a strain of Vibrio cholera that she isolated from a sick football player at the Olin Health Center. She cut the plasmid with EcoRI, mixed the pieces with an EcoRI fragment of DNA from a transposon that contains a tetracycline-resistanec gene (tetR), and added DNA ligase to the mixture. Then she used the soup of ligated DNAs to transform recomination-deficient (RecA0) E. coli cells, and plated the transformed cells on medium supplemented with tetracycline. The next day, she found about fifty TetR colonies on her plates. The appearance of the TetR E. coli colonies indicated (virtually proved) that:
A. The intern had ligated pieces of DNA containing the tetR gene into the chromosome of the recipient E. coli cells
B. Segements of the ligated DNA were homologous to segments of the bacterial DNA and had integrated into the bacterial chromosome by recombination.
C. The TetR transformants contained circular DNA constructs consisting of at lest the orV from the plasmid and the tetR gene from the transposon.
D. The Tetr transformants replicated the linear piece of transposon DNA that contained the tetr gene because they are RecA-
E. The sick student was infected by a tetracycline resistant strain of shigella.
I have 52 seconds to read and solve this problem. How long will it take you?
:frust::splat:
48. An ambitious intern discovered a 100-kb circular plasmid in a strain of Vibrio cholera that she isolated from a sick football player at the Olin Health Center. She cut the plasmid with EcoRI, mixed the pieces with an EcoRI fragment of DNA from a transposon that contains a tetracycline-resistanec gene (tetR), and added DNA ligase to the mixture. Then she used the soup of ligated DNAs to transform recomination-deficient (RecA0) E. coli cells, and plated the transformed cells on medium supplemented with tetracycline. The next day, she found about fifty TetR colonies on her plates. The appearance of the TetR E. coli colonies indicated (virtually proved) that:
A. The intern had ligated pieces of DNA containing the tetR gene into the chromosome of the recipient E. coli cells
B. Segements of the ligated DNA were homologous to segments of the bacterial DNA and had integrated into the bacterial chromosome by recombination.
C. The TetR transformants contained circular DNA constructs consisting of at lest the orV from the plasmid and the tetR gene from the transposon.
D. The Tetr transformants replicated the linear piece of transposon DNA that contained the tetr gene because they are RecA-
E. The sick student was infected by a tetracycline resistant strain of shigella.
I have 52 seconds to read and solve this problem. How long will it take you?
:frust::splat: