A plasmid vector, with a lambda cos site.

Ori

MCS

Antibiotic resistance

cos site for lambda DNA packaging

can package up to 50Kb

Method of cloning - linearise cosmid at restriction site and add DNA. Ligate all cosmids together. In vivo phage packaging recognises cos sites 35-45Kb apart. Infect E.coli and re-circularise.

The phage shell is made in bacteria using 2 strains: one with mutations to allow only head and tail production respectively. Protein extracts from the 2 cultures are taken and added to cosmid DNA.

These have the advantage of efficient introduction to bacteria (host).

	Created by Austin Davies almost 10 years ago

Lecture 19 - Module 4