1)  Insertion vectors:

•  Foreign DNA sequence is inserted into the λ genome without any significant change of the wild type genome.

•  Smaller insert size (upto ~10kb).

•  They may contain a multiple cloning site inserted in lacZ system for screening of recombinant bacterial colonies.

•  Can be used to clone smaller DNA molecule.

•  Eg: λ ZAP, λ gt etc.

Fig 1-4.2.1: Insertion vector

2)  Replacement vectors:

•  Full length λ molecule having two identical restriction sites flanked by “stuffer fragment”.

•  Stuffer fragment is replaced by foreign DNA during restriction cloning.

•  The vector without the foreign insert cannot be packaged due to the size limitation (smaller than the required).

•  Insert size ranges between 10-23 kb.

•  Eg. λ EMBL 3, λ EMBL 4, λ DASH etc.

Fig 1-4.2.2: Replacement vector