Cosmid __full__ -

Today, although superseded by BACs for many applications due to the latter’s even larger capacity (100–350 kb) and lower recombination rates, cosmids remain useful for targeted cloning, subcloning of large gene clusters, and functional studies in microbial genetics.

A cosmid is essentially a small, high-copy-number plasmid that has been engineered to contain one critical element from the lambda phage—the . This 200-base-pair sequence is the only phage component retained; cosmids lack all other lambda genes required for viral packaging, replication, or lysis. cosmid

Cosmids were the vector of choice for constructing genomic libraries of complex organisms before the advent of YACs (Yeast Artificial Chromosomes) and BACs (Bacterial Artificial Chromosomes). They played a crucial role in early mapping of the human genome, sequencing of C. elegans , and isolation of disease-related genes such as the cystic fibrosis transmembrane conductance regulator ( CFTR ). Today, although superseded by BACs for many applications