Read the following passage and answer the questions that follow :
We know that plasmids and bacteriophages are the most commonly used vectors in biotechnology experiments. If we can link an alien piece of DNA to the plasmid DNA, the alien DNA can be multiplied equal to the copy number of the plasmid. Engineered vectors are used these days. Study the diagram of the E. coli cloning vector pBR322 and answer the questions that follow :
(c) Name the two restriction sites each in the two genes you have identified as selectable markers.
Show Hint
ampR has PstI and PvuI. tetR has BamHI and SalI (ClaI and HindIII are also in tetR).
Step 1: Link the markers to the map:
The selectable markers identified earlier are ampR (gene G) and tetR (gene H).
Each marker carries its own restriction sites, shown as the labelled lines on the ring.
Step 2: Sites in ampR:
The ampR gene has the sites PstI and PvuI (labelled D and E on the left of the ring).
Step 3: Sites in tetR:
The tetR gene has sites such as BamHI and SalI (A and B on the right side). ClaI and HindIII, shown at the top, also lie in tetR.
Step 4: Write the answer:
Two sites in each gene are asked for, so write PstI and PvuI for ampR, and BamHI and SalI (or ClaI and HindIII) for tetR.
Final Answer:
ampR: PstI and PvuI. tetR: BamHI and SalI (ClaI and HindIII are also in tetR).
