Question

Explain the importance of ‘ori’ and ‘rop’ in the \textit{E. coli}cloning vector shown in the above diagram.

Hint:

‘ori’ is essential for plasmid replication, and ‘rop’ fine-tunes the process to avoid overburdening the host cell.

Answer 1

Step 1: ‘ori’ (origin of replication) is a DNA sequence that initiates the replication of the plasmid within the host \textit{E. coli} cell.
Step 2: The presence of ‘ori’ ensures that the plasmid can replicate independently of the host chromosome, allowing multiple copies of the recombinant DNA to be produced per cell.
Step 3: ‘rop’ (repressor of primer) is a gene that encodes a protein regulating the copy number of the plasmid by controlling replication at the ‘ori’.
Step 4: The ‘rop’ protein helps maintain a stable, moderate copy number of the plasmid, preventing over-replication, which could be toxic to the host cell.
Thus, ‘ori’ enables replication, while ‘rop’ ensures controlled replication for efficient cloning.