Identify the correct statements regarding features of a vector.

A. They should have ability to replicate within the host

B. They should have 'ori' sites that start replication

C. Its origin should not support high copy number

D. They should have more than one recognition sites for restriction enzymes

Choose the correct answer from the options given below:

A and B only

The correct answer is Option (3) -A and B only

Origin of replication (ori) is a sequence from where replication starts and any piece of DNA when linked to this sequence can be made to replicate within the host cells. This sequence is also responsible for controlling the copy number of the linked DNA. So, if one wants to recover many copies of the target DNA it should be cloned in a vector whose origin support high copy number.

In order to link the alien DNA, the vector needs to have very few, preferably single, recognition sites for the commonly used restriction enzymes. Presence of more than one recognition sites within the vector will generate several fragments, which will complicate the gene cloning.