Gene cloning is the act of making copies of a single gene. This technology has been around since the 1970s, and it has become a common practice in molecular biology labs today. Scientists studying a particular gene often use bacterial plasmids to generate multiple copies of the same gene. Plasmids are self-replicating extra-chromosomal circular DNA molecules, distinct from the normal bacterial genome.                                                                Plasmids and other types of cloning vectors were used by Human Genome Project researchers to copy genes and other pieces of chromosomes to generate enough identical material for further study. To clone a gene, a DNA fragment containing the gene of interest is isolated from chromosomal DNA using restriction enzymes and then united with a plasmid that has been cut with the same restriction enzymes. When the fragment of chromosomal DNA is joined with its cloning vector in the lab, it is called a "recombinant DNA molecule." Following introduction into suitable host cells, the recombinant DNA can then be reproduced along with the host cell DNA. Cloned genes are useful in a wide array of experiments and practical medical applications ranging from genetic fingerprinting to large scale protein production and gene therapy. Gene cloning technology has revolutionized molecular and cell biology and advances have been made at an incredible pace in the last 10-15 years. The most notable recent advances are the development of high-throughput sequencing and real-time PCR.

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