Bacteriophage based vector
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Lamda phage has a linear double stranded DNA genome of 48,514 bp with 12 base complementary cos sites at each end used for packaging DNA into phage heads. The central region causes lytic infection and allows desired genes to replace infected genes, with a cloning capacity of 23 kb. M13 phage infects E. coli with F pili and has a single stranded circular genome of 6,407 bp that enters bacteria from a double stranded replicative form. Replication becomes asymmetric after 100 copies are formed, producing single stranded copies extracted from host cells as M13 phage and double stranded replicative form. M13 phage is used for site-directed mutagenesis and DNA sequencing.
Bacteriophage based vector
- 1. Lamda phage- It has a double stranded,linearDNA GENOMEOF 48514 bp. Presence of 12 basesat the bothend. These are unpairedbutcomplementarycalledcossites. Cos site isusedforpackagingDNA intophage heads. The central regionof the genome causeslyticinfection. Therefore,infectedgenesare substitutedorreplacedbydesiredgenes. Cloningcapacityis23 kb. Fig.Lamda phage M13 Phage- It isa filamentousphage,infectE.coli havingFpili. Genome issingle strandedcircular,6407bp insize. Single strandedgenomeentersintobacteriafromdouble strandardmoleculecalledReplicative form. Afterforming100 copiesina cell at thatpointreplicationbecome asymmetricandsingle stranded copiesare produced. These are extractedoutfromthe hostcelsas M13 PHAGE ANDDOUBLE STRANDEDreplicative form. Application- It isusedin site-directedmutagenesisandDNA sequencing.