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 :
(b) (i) Identify :
(I) The gene in the cloning vector that controls the copy number of the vector.
(II) The restriction site - C in the "rop" gene.
Show Hint
Copy number is controlled by ori; the rop gene carries the Pvu II site.
Step 1: Part (I): copy number:
The origin of replication (ori) is the sequence from where replication of the plasmid begins.
It decides how many copies of the plasmid, and of the linked alien DNA, are made in the cell. The vector region marked ori is the answer.
Step 2: Part (II): site C:
Site C is the restriction site inside the rop gene, which codes for the Rop protein (a protein that helps control plasmid replication).
The restriction site present in the rop gene of pBR322 is Pvu II.
Final Answer:
(I) ori (origin of replication), the region that controls copy number; (II) the restriction site C in rop is Pvu II.
