1. Types of cloning vectors 1. Plasmids: Autonomously replicating circular DNA molecules. 2.Bacteriophage: Small viruses that infect bacteria cells. 3. Vectors for large DNA inserts: Examples: Cosmids PACs BACs

2. Bacteriophage Vectors Lambda: Each clone can accept inserts of ~15-20 kb. Replace part of DNA that is not needed for replication with genomic DNA fragments. M13: Small inserts (1-2 kb) But, phage particles contain single stranded DNA.

3. Lambda Bacteriophage Vectors cos Selection: Only recombinant phage produce plaques. 1. Size limits of DNA that fits into phage particle. left arm (20kb) + right arm (9kb) + insert (~15kb) = 44kb 2. Requirement for genetic information: cos sites & genes in right & left arms.

4. Cosmids: Plasmids that contain cos sites. This allows them to be packaged into particles. But don’t have genes, therefore can clone larger insert fragments; 35-45 kb.