Question

If you want to recover many copies of the target $DNA$, you will choose a vector

• A. which does not have origin of replication
• B. which has antibiotic resistance gene
• C. whose origin supports high copy number
• D. which has only one restriction site

Answer 1

Answer: (C)

Vectors that have high number per cell will have high copy number of their genome within the bacterial cell. If we link an alien piece of $DNA$ with vector, we can multiply its number equal to the copy number of the vector. Any piece of $DNA$ when linked to the ${}^{\prime }ori$ sequence, can be made to replicate within the host cells. This property of ${}^{\prime }ori$ is used to make a number of copies of the linked $DNA$. If we want to obtain many copies of the target $DNA$, then it should be cloned in such a vector whose ${}^{\prime }ori$ supports high copy number.