Cosmid

Cosmid is a type of plasmid, specifically a type of vector, that is used for cloning in bacteria. Cosmids can be used to build large clone libraries of DNA fragments. They are a hybrid of features from plasmids and bacteriophage lambda.

History

Cosmids were first developed in the 1970s as a means of efficiently cloning larger DNA fragments. They were named "cosmids" as they contain the cos sites of bacteriophage lambda, which allow the DNA to be packaged into lambda phage particles.

Structure and Function

Cosmids are small, circular pieces of DNA that are used as vectors to clone DNA fragments (inserts) in bacterial cells. They are similar to plasmids in many ways, but they also contain the cos sites from bacteriophage lambda, which allow the DNA to be packaged into lambda phage particles. This allows the cosmid to carry larger inserts of DNA than a plasmid can.

Cosmids can carry 37 to 52 kilobases of foreign DNA, which is much larger than most other vectors. This makes them useful for creating DNA libraries, where large numbers of different DNA fragments are needed.

Applications

Cosmids are used in molecular biology research, particularly in cloning and creating DNA libraries. They are also used in genomics for sequencing large genomes.

See Also

• Plasmid
• Vector
• Cloning
• Bacteriophage lambda
• Genomics

References

Cosmid Resources
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