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A recombinantly engineered plasmid, a circular DNA containing, in order: a plasmid origin of replication and a drug-resistance marker, the cos (cohesive end) site from bacteriophage λ, and a fragment of eukaryotic DNA to be cloned; cosmids are constructed to permit cloning of fragments of up to about 40,000 base pairs in length, with one or more unique restriction sites being necessary to facilitate cloning.
An artificially constructed plasmid used for cloning large genes or other DNA sequences.
cosmida class of CLONING VECTOR which comprises a bacterial PLASMID and the COS SITE of a BACTERIOPHAGE, typically bacteriophage lambda. A cosmid combines features of plasmids and of bacteriophages and can be used in CLONING. Large DNA fragments, up to 40 KILOBASE pairs in size, can be cloned in cosmids. The cosmid can be propagated as a plasmid in vivo and packaged into bacteriophages in vitro.
a class of plasmid-based vectors carrying the bacteriophage λ cos sequences required for packaging of DNA into phage particles. Used for cloning large DNA fragments (up to 45 kilobases). Recombinant molecules constructed using cosmids are incorporated into bacteriophage using in vitro packaging extracts and introduced with high efficiency into Escherichia coli.