Chapter 20 - Chapter 20 - DNA Technology and Genomics...

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Chapter 20 - DNA Technology and Genomics Chapter 20 DNA Technology and Genomics Lecture Outline Overview: Understanding and Manipulating Genomes One of the great achievements of modern science has been the sequencing of the human genome, which was largely completed by 2003. 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. The methods for making recombinant DNA are central to genetic engineering, the direct manipulation of genes for practical purposes. o Applications include the introduction of a desired gene into the DNA of a host that will produce the desired protein. DNA technology has launched a revolution in biotechnology, the manipulation of organisms or their components to make useful products. o 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. These techniques exploit naturally occurring mutations and genetic recombination. 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. DNA technology is now applied in areas ranging from agriculture to criminal law, but its most important achievements are in basic research. Concept 20.1 DNA cloning permits production of multiple copies of a specific gene or other DNA segment 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. Techniques for gene cloning enable scientists to prepare multiple identical copies of gene-sized pieces of DNA. One basic cloning technique begins with the insertion of a foreign gene into a bacterial plasmid. o E. coli and its plasmids are commonly used. o First, a foreign gene is inserted into a bacterial plasmid to produce a recombinant DNA molecule. o The plasmid is returned to a bacterial cell, producing a recombinant bacterium, which reproduces to form a clone of identical cells. o Every time the bacterium reproduces, the recombinant plasmid is replicated as well.
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o Under suitable conditions, the bacterial clone will make the protein encoded by the foreign gene. The potential uses of cloned genes fall into two general categories. o First, the goal may be to produce a protein product. For example, bacteria carrying the gene for human growth hormone can produce large quantities of the hormone. o Alternatively, the goal may be to prepare many copies of the gene itself. This may enable scientists to determine the gene’s nucleotide sequence or
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This note was uploaded on 07/22/2009 for the course BIOL 01 taught by Professor Sheeter during the Spring '09 term at St. Edwards.

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Chapter 20 - Chapter 20 - DNA Technology and Genomics...

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