![]() The hybrid cosmid DNA in the capsids can then be transferred into bacterial cells by transduction. Unlike plasmids, they can also be packaged in vitro into phage capsids, a step which requires cohesive ends, also known as cos sites also used in cloning with a lambda phage as a vector, however nearly all the lambda genes have been deleted with the exception of the cos sequence. ![]() Those cells which did not take up the cosmid would be unable to grow. They frequently also contain a gene for selection such as antibiotic resistance, so that the transformed cells can be identified by plating on a medium containing the antibiotic. They can replicate as plasmids if they have a suitable origin of replication (ori): for example SV40 ori in mammalian cells, ColE1 ori for double-stranded DNA replication, or f1 ori for single-stranded DNA replication in prokaryotes. Ĭosmids can contain 37 to 52 (normally 45) kb of DNA, limits based on the normal bacteriophage packaging size. ![]() They were first described by Collins and Hohn in 1978. Cosmids can be used to build genomic libraries. They are often used as a cloning vector in genetic engineering. ( Learn how and when to remove this template message)Ī cosmid is a type of hybrid plasmid that contains a Lambda phage cos sequence. JSTOR ( April 2014) ( Learn how and when to remove this template message).Unsourced material may be challenged and removed. Please help improve this article by adding citations to reliable sources. This article needs additional citations for verification.
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