1. Tardigrade
  2. Question
  3. Biology
  4. When we ligate a foreign DNA at the SalI site of pBR322, the a plasmid will lose tetracycline resistance due to the insertion of foreign DNA but can still be selected out from b ones by plating the c on ampicillin containing medium.

Q. When we ligate a foreign DNA at the SalI site of pBR322, the ___a___ plasmid will lose tetracycline resistance due to the insertion of foreign DNA but can still be selected out from ___b___ ones by plating the ___c___ on ampicillin containing medium.

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Solution:

pBR322 is an E.coli plasmid that contains origin of replication, ampicillin-resistant gene, tetracycline resistance gene, and multiple cloning site. It is a highly studied plasmid vector. Because it has two resistance genes, transformed cells can be screened from non-transformed by process of insertional inactivation in which target DNA when inserted into tetracycline gene, disrupt the gene and making cell recombinant with resistance to ampicillin only. Hence, colonies formed on the ampicillin plate are those which contain target DNA.