Question

This is figure of plasmid pBR 322. The gene conferring resistance to ampicillin (ApR) can be interrupted by insertion of a DNA fragment into the Pstl site, and the gene conferring resistance to tetracycline (TcR) can be interrupted by insertion of a DNA fragment into the BamHI site. Replication is controlled by the CoIEl origin. Use of the TcR and ApR genes allows for easy screening for recombinants carrying inserts of foreign DNA. For locating Eco RI, TcR and ApR gene on it. Identify, what is represented by A, B and C.

• A. A- TeR, B- ApR and C- EcoRI
• B. A- EcoRI, B- ApR and C- TcR
• C. A- TeR, B- EcoRI and C- ApR
• D. A- ApR, B- tet R and C- EcoRI

Answer 1

The correct option is D A- ApR, B- tet R and C- EcoRI

pBR322 is a plasmid and was one of the first widely used E. coli cloning vectors. pBR322 contains the ampR gene (A), encoding the ampicillin resistance protein and the tetR gene (B), encoding the tetracycline resistance protein and the rop gene, encoding a restrictor of plasmid copy number. Restriction endonucleases EcoRI (C) and HindIII are used to analyze the structure of the plasmid genome responsible for the EcoRI restriction endonuclease and modification methylase.

Therefore, the correct answer is option D.