The specific sequence of DNA that initiates replication of alien DNA in rDNA technology is called:
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → Origin of replication
A piece of alien (foreign) DNA cannot multiply on its own inside a host. It multiplies only when it is linked to a DNA sequence from which replication starts. This sequence is the origin of replication (ori). A cloning vector carries an ori, so any DNA joined to the vector is copied along with it. The ori also controls the copy number of the linked DNA.
NCERT Extract:
Principles of Biotechnology – “… In a chromosome there is a specific DNA sequence called the origin of replication, which is responsible for initiating replication. Therefore, for the multiplication of any alien piece of DNA in an organism it needs to be a part of a chromosome(s) which has a specific sequence known as ‘origin of replication’. Thus, an alien DNA is linked with the origin of replication, so that, this alien piece of DNA can replicate and multiply itself in the host organism.”
Cloning Vectors – “… (i) Origin of replication (ori) : This 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.”