Genetic engineering: Difference between revisions
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that's how babies are made! |
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[[Image:Genetic-engineering-wheat.jpg|thumb|right|200px|Elements of genetic engineering]] |
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{{for|a non-technical introduction to the topic|Introduction to Genetics}} |
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'''Genetic engineering''', '''recombinant DNA technology''', '''genetic modification/manipulation (GM)''' and '''gene splicing''' are terms that apply to the direct manipulation of an [[organism]]'s [[gene]]s.<ref> |
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{{cite web |
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|url=http://dictionary.reference.com/browse/Genetic%20engineering |
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|title=Genetic engineering - Definitions from Dictionary.com |
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|publisher=dictionary.reference.com |
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|accessdate=2008-04-26 |
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}} |
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</ref>Genetic Engineering is different from traditional [[breeding]], where the organism's genes are manipulated indirectly; genetic engineering uses the techniques of [[molecular cloning]] and [[transformation]] to alter the structure and characteristics of genes directly. Genetic engineering techniques have |
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found some successes in numerous applications. Some examples are in improving crop technology, the manufacture of synthetic human [[insulin]] through the use of modified [[bacteria]], the manufacture of [[erythropoietin]] in Chinese hamster [[ovary]] cells, and the production of new types of experimental mice such as the [[oncomouse]] (cancer mouse) for research. |
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Since a [[protein]] sequence is specified by a segment of DNA called a gene, novel versions of that protein can be produced by changing the DNA sequence of the gene. |
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== Engineering == |
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[[Image:Btcornafrica.jpg|[[Kenya]]ns examining insect-resistant transgenic [[Bacillus thuringiensis|Bt]] corn.|thumb]] |
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There are several ways through which genetic engineering is accomplished. Essentially, the process has five main steps: |
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# Isolation of the genes of interest |
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# Insertion of the genes into a transfer [[vector (biology)|vector]] |
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# transfer of vector to the organism to be modified |
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# [[Transformation (genetics)|Transformation]] of cells of organism |
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# Separation of the genetically modified organism (GMO) from those that have not been successfully modified |
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'''Isolation''' is achieved by identifying the gene of interest that the scientist wishes to insert into the organism, usually using existing knowledge of the various functions of genes. DNA information can be obtained from [[cDNA]] or [[gDNA]] libraries, and amplified using [[PCR]] techniques. If necessary, i.e. for insertion of eukaryotic genomic DNA into [[prokaryotes]], further modification may be carried out such as removal of [[introns]] or ligating prokaryotic promoters. |
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'''Insertion''' of a gene into a vector such as a [[plasmid]] can be done once the gene of interest is isolated. Other vectors can also be used, such as viral vectors, and non-prokaryotic ones such as [[liposomes]], or even direct insertion using [[gene gun]]s. [[Restriction enzyme]]s and [[ligases]] are of great use in this crucial step if it is being inserted into prokaryotic or viral vectors. Daniel Nathans, Werner Arber and Hamilton Smith received the [[1978]] [[Nobel Prize]] [[Nobel Prize in Physiology or Medicine|in Physiology or Medicine]] for their isolation of [[restriction enzyme|restriction endonucleases]]. |
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Once the vector is obtained, it can be used to '''transform''' the '''target organism'''. Depending on the vector used, it can be complex or simple. For example, using raw DNA with DNA guns is a fairly straightforward process but with low success rates, where the DNA is coated onto particles such as gold and fired directly into a cell. Other more complex methods, such as [[Transformation (genetics)|bacterial transformation]] or using viruses as vectors have higher success rates. |
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After transformation, the '''GMO''' can be '''isolated''' from those that have failed to take up the vector in various ways. |
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=== Applications === |
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The first genetically engineered medicine was synthetic human [[insulin]], approved by the [[United States]] [[Food and Drug Administration]] |
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in [[1982]]. Scientists used bacteria in which they inserted plasmids containing the directions for insulin, they were then able to use the bacteria to produce and harvest artificial insulin. Another early application of genetic engineering was to create human growth hormone as replacement for a drug that was previously extracted from human [[cadaver]]s. In [[1987]] the FDA approved the first genetically engineered [[vaccine]] for humans, for [[hepatitis B]]. Since these early uses of the technology in medicine, the use of GM has gradually expanded to supply a number of other drugs and vaccines. |
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One of the best known applications of genetic engineering is the creation of [[genetically modified organisms]] (GMOs) such as foods and vegetables that resist pest and bacteria infection and have longer freshness than otherwise. |
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There are potentially momentous [[biotechnology|biotechnological]] applications of GM, for example oral [[vaccine]]s produced naturally in fruit, at very low cost for most of the country. |
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=== Genetic engineering and research === |
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Although there has been a tremendous[http://www.pitt.edu/~biology/] revolution in the biological sciences in the past twenty years, there is still a great deal that remains to be discovered. The completion of the sequencing of the [[human genome]], as well as the genomes of most agriculturally and scientifically important animals and plants, has increased the possibilities of genetic research immeasurably. Expedient and inexpensive access to comprehensive genetic data has become a reality with billions of sequenced [[nucleotide]]s already online and annotated. |
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[[Image:PCWmice1.jpg|thumb|right|Knockout mice]] |
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* '''Loss of function experiments''', such as in a [[Gene knockout|gene knockout]] experiment, in which an organism is engineered to lack the activity of one or more genes. This allows the experimenter to analyze the defects caused by this [[mutation]], and can be considerably useful in unearthing the function of a gene. It is used especially frequently in [[developmental biology]]. A knockout experiment involves the creation and manipulation of a DNA construct ''[[in vitro]]'', which, in a simple knockout, consists of a copy of the desired gene which has been slightly altered such as to cripple its function. The construct is then taken up by [[embryonic stem cells]], where the engineered copy of the gene replaces the organism's own gene. These stem cells are injected into [[blastocyst]]s, which are implanted into surrogate mothers. Another method, useful in organisms such as [[Drosophila]] (fruitfly), is to induce mutations in a large population and then screen the progeny for the desired mutation. A similar process can be used in both plants and [[prokaryotes]]. |
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* '''Gain of function experiments''', the logical counterpart of knockouts. These are sometimes performed in conjunction with knockout experiments to more finely establish the function of the desired gene. The process is much the same as that in knockout engineering, except that the construct is designed to increase the function of the gene, usually by providing extra copies of the gene or inducing synthesis of the protein more frequently. |
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[[Image:GFP structure.png|thumb|right|175px|Green Fluorescent Protein ribbon diagram. From {{PDB|1EMA}}.]] |
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* '''Tracking experiments''', which seek to gain information about the localization and interaction of the desired protein. One way to do this is to replace the wild-type gene with a 'fusion' gene, which is a juxtaposition of the wild-type gene with a reporting element such as [[Green fluorescent protein|Green Fluorescent Protein]] (GFP) that will allow easy visualization of the products of the genetic modification. While this is a useful technique, the manipulation can destroy the function of the gene, creating secondary effects and possibly calling into question the results of the experiment. More sophisticated techniques are now in development that can track protein products without mitigating their function, such as the addition of small sequences which will serve as binding motifs to monoclonal antibodies. |
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* '''Expression studies''' aim to discover where and when specific proteins are produced. In these experiments the DNA sequence before the DNA that codes for a protein, known as a gene's [[promoter]] is reintroduced into an organism with the protein coding region replaced by a reporter gene such as GFP or an enzyme that catalyzes the production of a dye. Thus the time and place where a particular protein is produced can be observed. Expression studies can be taken a step further by altering the promoter to find which pieces are crucial for the proper expression of the gene and are actually bound by transcription factor proteins; this process is known as promoter bashing. |
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===Human genetic engineering=== |
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{{seealso|Human Genetic Engineering}} |
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Human genetic engineering can be used to treat [[genetic disease]], but there is a difference between treating the disease in an individual and in changing the genome that gets passed down to that person's descendants (germ-line genetic engineering). |
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Human genetic engineering is already being used on a small scale to allow infertile women with genetic defects in their [[mitochondria]] to have children.<ref name="bbc"> |
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{{cite web |
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|url=http://news.bbc.co.uk/1/hi/sci/tech/1312708.stm |
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|title=BBC News | SCI/TECH | Genetically altered babies born |
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|publisher=news.bbc.co.uk |
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|accessdate=2008-04-26 |
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</ref> Healthy human eggs from a second mother are used. The child produced this way has genetic information from two mothers and one father.<ref name="bbc"/> The changes made are germ line changes and will likely be passed down from generation to generation, thus are a permanent change to the human genome.<ref name="bbc"/> |
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Human genetic engineering has the potential to change human beings' appearance, adaptability, intelligence, character and behavior. It may potentially be used in creating more dramatic changes in humans. There are many unresolved ethical issues and concerns surrounding this technology, and it remains a controversial topic. |
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==References== |
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{{refimprove|date=September 2007}} |
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{{Reflist}} |
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==Reading list== |
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*{{cite book | author=British Medical Association | title=The Impact of Genetic Modification on Agriculture, Food and Health | publisher=BMJ Books | year=1999 | id=ISBN 0-7279-1431-6}} |
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*{{cite book | author=Donnellan, Craig | title=Genetic Modification (Issues) | publisher=Independence Educational Publishers | year=2004 | id=ISBN 1-86168-288-3}} |
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*{{cite book | author=Morgan, Sally | title=Superfoods: Genetic Modification of Foods (Science at the Edge) | publisher=Heinemann | year=2003 | id=ISBN 1-4034-4123-5}} |
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*{{cite book | author=Smiley, Sophie | title=Genetic Modification: Study Guide (Exploring the Issues) | publisher=Independence Educational Publishers | year=2005 | id=ISBN 1-86168-307-3}} |
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*{{cite book |last=Zaid |first=A |authorlink= |coauthors= H.G. Hughes, E. Porceddu, F. Nicholas|title= Glossary of Biotechnology for Food and Agriculture - A Revised and Augmented Edition of the Glossary of Biotechnology and Genetic Engineering. Available in English, French, Spanish, Arabic|url=http://www.fao.org/biotech/index_glossary.asp|year=2001|publisher=[[FAO]]|location=[[Rome, Italy]]|id= ISBN 92-5-104683-2}} |
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==See also== |
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<div style="-moz-column-count:3; column-count:3;"> |
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*[[Bioethics]] |
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*[[Biotechnology]] |
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*[[Biological engineering]] |
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*[[Canola]] |
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*[[Cloning]] |
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*[[Ethics of technology]] |
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*[[Eugenics]] |
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*[[Experimental evolution]] |
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*[[Genetic erosion]] |
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*[[Gene flow]] |
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*[[Genetic pollution]] |
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*[[Gene pool]] |
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*[[Genetically modified food]] |
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*[[Genetically modified organisms]] |
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*[[Transgene]] |
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*[[Human genetic engineering]] |
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*[[Ice-minus bacteria]] |
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*[[List of emerging technologies]] |
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*[[Marker assisted selection]] |
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*[[Monsanto]] |
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*[[Recombinant DNA]] |
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*[[Research ethics]] |
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*[[Stem cell]] |
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*[[Synthetic biology]] |
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*[[Transgenic bacteria]] |
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*[[Paratransgenesis]] |
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</div> |
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==External links== |
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===General=== |
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*[http://www.drze.de/themen/blickpunkt/GHLhttp://www.drze.de/themen/blickpunkt/GHL-en?la=en- In Focus "Genetically modified foods:Technical and scientific aspects, ethical aspects and legal aspects" (German Reference Centre for Ethics in the Life Sciences)] |
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*[http://www.bbsrc.ac.uk/life/ingeneious/3_1/3_1_1.html BBSRC - The science behind genetic modification] |
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*[http://www.mfe.govt.nz/publications/organisms/royal-commission-gm/ Ministry for the Environment NZ - Report of the Royal Commission on Genetic Modification] |
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*[http://www.gmo-safety.eu/en/ GMO Safety - Information about research projects on the biological safety of genetically modified plants.] |
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*[http://www.rsrevision.com/Alevel/ethics/genetic_engineering/index.htm Genetic Engineering] A UK site for students, with case studies and ethical responses |
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*[http://www.bootstrike.com/Genetics/ Introduction to Genetic Engineering] Covers general information on Genetic Engineering including cloning, stem cells and DNA. |
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* [http://www.genetherapynet.com Gene Therapy Net] |
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* [http://www.mshri.on.ca/nagy/tt2008/ The 8th International Transgenic Technology Conference] |
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===News=== |
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{{Wikinews|Genetically altered mice are "superathletes," November 2, 2007}} |
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*[http://news.bbc.co.uk/1/hi/sci/tech/1312708.stm Genetically altered babies born, BBC News, Friday, 4 May, 2001] |
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*[http://www.defra.gov.uk/environment/gm/index.htm DEFRA - Genetic Modification (GM)] |
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*[http://news.bbc.co.uk/1/hi/sci/tech/6197768.stm BBC News - GM potato trials given go-ahead] - 01/12/06 |
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*[http://www.brightsurf.com/news/headlines/31015/New_study_finds_genetically_engineered_crops_could_play_a_role_in_sustainable_agriculture.html Brightsurf Science News - New study finds genetically engineered crops could play a role in sustainable agriculture] - 06/08/07 |
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* [http://reportergene.blogspot.com Research highlights] on reporter genes used in genetic engineering |
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{{WVD}} |
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[[Category:Bioengineering]] |
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[[Category:Biotechnology]] |
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[[Category:Genetic engineering| ]] |
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[[Category:Molecular biology]] |
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[[af:Genetiese manipulasie]] |
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[[ca:Enginyeria genètica]] |
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[[da:Gensplejsning]] |
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[[de:Gentechnik]] |
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[[es:Ingeniería genética]] |
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[[eo:Gentekniko]] |
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[[fr:Génie génétique]] |
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[[ko:유전공학]] |
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[[hr:Genetičko inženjerstvo]] |
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[[id:Rekayasa genetika]] |
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[[it:Ingegneria genetica]] |
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[[he:הנדסה גנטית]] |
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[[ku:Endazyariya bûmayîk]] |
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[[nl:Genetische technologie]] |
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[[ja:遺伝子工学]] |
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[[nn:Gensløyd]] |
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[[pl:Inżynieria genetyczna]] |
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[[pt:Engenharia genética]] |
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[[ru:Генная инженерия]] |
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[[simple:Genetic engineering]] |
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[[sr:Генетички инжењеринг]] |
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[[su:Rékayasa genetik]] |
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[[fi:Geenitekniikka]] |
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[[sv:Genetisk modifiering]] |
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[[th:พันธุวิศวกรรม]] |
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[[vi:Kỹ thuật di truyền]] |
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[[tr:Genetik mühendisliği]] |
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[[uk:Генна інженерія]] |
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[[zh:遺傳工程]] |
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Revision as of 04:54, 30 July 2008
that's how babies are made!