Question

Choose the incorrect statement for PAC vectors.

(a) In these vectors, the phage packaging signals are removed but the two P1 origin of replication persist

(b) They resemble BAC vectors

(c) They accept an insert of upto 300 kbp

(d) Instability is observed

I have been asked this question in an interview for job.

The doubt is from Bacteriophage-Mu and Bacteriophage-Pi in section Other Vector Systems for E of Genetic Engineering

Answer 1

The correct choice is (d) Instability is observed

The explanation is: PAC vectors are those vectors, in which the phage packaging signals are removed but the two P1 origin of replication persist. These resemble BAC vectors. They accept upto an insert of upto 300 kbp. Maintenance at low copy numbers is helpful in avoiding instability.