Gene cloning and genetic engineering were made possible by the discovery of restriction enzymes that cut DNA molecules at specific locations.Restriction enzymes are used to make recombinant DNA. Most protein-coding genes exist in only one copy per genome, so the ability to clone rare DNA fragments is very valuable.This may enable scientists to determine the gene’s nucleotide sequence or provide an organism with a new metabolic capability by transferring a gene from another organism.Alternatively, the goal may be to prepare many copies of the gene itself.For example, bacteria carrying the gene for human growth hormone can produce large quantities of the hormone.First, the goal may be to produce a protein product.The potential uses of cloned genes fall into two general categories.Under suitable conditions, the bacterial clone will make the protein encoded by the foreign gene.Every time the bacterium reproduces, the recombinant plasmid is replicated as well.The plasmid is returned to a bacterial cell, producing a recombinant bacterium, which reproduces to form a clone of identical cells.First, a foreign gene is inserted into a bacterial plasmid to produce a recombinant DNA molecule.One basic cloning technique begins with the insertion of a foreign gene into a bacterial plasmid.Techniques for gene cloning enable scientists to prepare multiple identical copies of gene-sized pieces of DNA.To study a particular gene, scientists needed to develop methods to isolate the small, well-defined portion of a chromosome containing the gene of interest.DNA technology is now applied in areas ranging from agriculture to criminal law, but its most important achievements are in basic research.Ĭoncept 20.1 DNA cloning permits production of multiple copies of a specific gene or other DNA segment.Biotechnology based on the manipulation of DNA in vitro differs from earlier practices by enabling scientists to modify specific genes and move them between organisms as distinct as bacteria, plants, and animals.These techniques exploit naturally occurring mutations and genetic recombination.Practices that go back centuries, such as the use of microbes to make wine and cheese and the selective breeding of livestock, are examples of biotechnology.DNA technology has launched a revolution in biotechnology, the manipulation of organisms or their components to make useful products.Applications include the introduction of a desired gene into the DNA of a host that will produce the desired protein.The methods for making recombinant DNA are central to genetic engineering, the direct manipulation of genes for practical purposes.Progress began with the development of techniques for making recombinant DNA, in which genes from two different sources-and often different species-are combined in vitro into the same molecule.One of the great achievements of modern science has been the sequencing of the human genome, which was largely completed by 2003.Overview: Understanding and Manipulating Genomes
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