Phage introduction/transduction:

Phage vector is used to carry and replicate foreign DNA inside the bacterial host system. The phage DNA inserts into the host chromosome by recombination. Phage λ had short regions of single-stranded DNA with complementary base sequences called “cohesive” (cos) sites. Base pairing between the complementary cos sites allows the linear genome to form a circle within the host bacterium. Circularized viral genome can be integrated into the bacterial genome by homologous recombination between attP site of viral genome and attB site of bacterial genome.

Fig 1-2.1: Bacteriophage λ genome circularization and recombination with bacterial genome

 

1-2.2 Methods involved in Recombinant DNA Technology :

Molecular cloning is a process for creating recombinant DNA and generally involves the following steps:

(1)  Selection of a cloning vector
(2)  Selection of a host organism
(3) Preparation of a vector DNA
(4) Preparation of DNA to be cloned
(5) Creation of recombinant DNA vector (having foreign DNA)
(6) Introduction of recombinant vector into host organism
(7) Selection of clones having insert vector.
(8) Screening and multiplication of recombinant clones with desired DNA inserts.



Fig 1-2.2: Steps in Gene Cloning