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Unformatted text preview: Chapter 22 Applications and Ethics of Biotechnology Biotechnology has revolutionized agriculture- transgenic crops and herbicide resistance o herbicides used to combat problem of crop infestations would end up also killing crop plants o herbicide-resistant plants created to improve crop yields also reduces environmental impact of herbicides o how to transfer resistance from one herbicide to another glyphosate herbicide effective at very low concentrations, not toxic to humans, and rapidly degraded by soil microorganisms isolation and cloning of EPSP synthase gene from glyphosate-resistant strain of E. coli gene cloned into vector and placed adjacent to plant virus promoter sequences and upstream from plant transcription- termination sequences recombinant vector transferred into bacterium o plasmid-carrying bacteria used to infect cells in discs cut from plant leaves glyphosate-resistant calluses were grown into transgenic plants and sprayed with glyphosate at concentrations 4 times higher than that needed to kill wild-type plants transgenic plants that overproduced EPSP synthase grew and developed, while control plants withered and died- nutritional enhancement of crop plants o gene transfer by recombinant DNA techniques offers a new way to enhance nutritional value of plants o many crop plants deficient in some of nutrients required in human diet biotechnology used to produce crops that meet dietary requirements golden rice enhanced levels for beta-carotene, precursor of vitamin A- concerns about genetically modified organisms o most genetically modified food products contain introduced gene encoding protein that confers a desired trait concern over genetically modified plants centers on issues of safety and environmental consequences safety are the plants safe to eat even with the enhancing chemicals environmental gene transfer by cross breeding with wild plants, toxicity, and invasiveness of modified plant, resulting in loss of natural species pharmaceutical products are synthesized in genetically altered organisms- insulin produced in bacteria o original method of synthetic human insulin synthetic genes for A and B subunits were constructed by oligonucleotide synthesis each oligonucleotide inserted into vector adjacent to lacZ lacZ gene and oligonucleotide transcribed and translated as unit o fusion polypeptide contained amino acid sequence for one of insulin subunits o insulin produced and purified by process packaged for use by diabetics- transgenic animal hosts and pharmaceutical products o bacterial hosts used to produce first generation of therapeutic proteins o some disadvantages in using prokaryotic hosts to synthesize eukaryotic...
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