Q. Normal E coli cells do not carry resistance against the antibiotics( written in NCERT on page number 199) then how the pbr322 is extracted from E coli which has antibiotic resistance genes?? Plzz solve dis dilemma.... expert has answered that pbr 322 contains antibiotic resistance genes it is not inserted from outside please refer to the screenshot given below how this possible as the pbr 322 is extracted from E coli and E coli do not carry any antibiotic resistant genes...
Dear student,
pbr 322 is the vector which is isolated from E coli. pbr 322 vector consist of antibiotic resistance gene and is not inserted from from outside.

Dear student

Please refer the solution below for the said query

pBR322 is not extracted from E. coli but was constructed in the laboratory of Herbert Boyer at the University of California by Bolivar and Rodriguez. The antibiotic resistance genes i.e tetracycline resistance gene is obtained from pSC101 plasmid of Salmonella panama and the ampicillin resistance gene is obtained from RSF 2124 plasmid found in some bacteria. 

pBR322 has two antibiotic resistance genes
1. bla gene encodes ampicillin resistance (AmpR) protein. 
2. tetA gene encodes the tetracycline resistance (TetR) protein.​


The E.coli is used to clone this vector to produce many copies.


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