Jump to content

Genetic engineering: Difference between revisions

From Wikipedia, the free encyclopedia
Browse history interactively
[pending revision][pending revision]
← Previous editNext edit →
Content deleted Content added
VisualWikitext
ClueBot (talk | contribs)
1,596,818 edits
m Reverting possible vandalism by 87.194.38.214 to version by Gwernol. False positive? Report it. Thanks, User:ClueBot. (413199) (Bot)
Line 15: Line 15:
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.
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.


4H DO NOT COPY FROM THIS WEBSITE!!!
== Engineering ==
[[Image:Btcornafrica.jpg|[[Kenya]]ns examining insect-resistant transgenic [[Bacillus thuringiensis|Bt]] corn.|thumb]]

There are several ways through which genetic engineering is accomplished. Essentially, the process has four main steps:

# Isolation of the genes of interest
# Insertion of the genes into a transfer [[vector (biology)|vector]]
# [[Transformation (genetics)|Transformation]] of cells of organism to be modified
# Separation of the genetically modified organism (GMO) from those that have not been successfully modified

'''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.

'''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]].

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.

After transformation, the '''GMO''' can be '''isolated''' from those that have failed to take up the vector in various ways.
=== Applications ===

The first genetically engineered medicine was synthetic human [[insulin]], approved by the [[United States]] [[Food and Drug Administration]]
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.
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.

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.

=== Genetic engineering and research ===
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.

[[Image:PCWmice1.jpg|thumb|right|Knockout mice]]

* '''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]].
* '''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.

[[Image:GFP structure.png|thumb|right|175px|Green Fluorescent Protein ribbon diagram. From {{PDB|1EMA}}.]]

* '''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.
* '''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.

===Human genetic engineering===
{{seealso|Human Genetic Engineering}}

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).

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">
{{cite web
|url=http://news.bbc.co.uk/1/hi/sci/tech/1312708.stm
|title=BBC News | SCI/TECH | Genetically altered babies born
|publisher=news.bbc.co.uk
|accessdate=2008-04-26
|last=
|first=
}}
</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"/>

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.


==References==
==References==

Revision as of 08:55, 10 June 2008

Elements of genetic engineering
For a non-technical introduction to the topic, see Introduction to Genetics.

Genetic engineering, recombinant DNA technology, genetic modification/manipulation (GM) and gene splicing are terms that apply to the direct manipulation of an organism's genes.[1] 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 endeavors have found some success 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.

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.

4H DO NOT COPY FROM THIS WEBSITE!!!

References

  1. ^ "Genetic engineering - Definitions from Dictionary.com". dictionary.reference.com. Retrieved 2008-04-26.

Reading list

See also

General

News

Wikinews has related news:


At Wikiversity, you can learn more and teach others about Genetic engineering at the Department of Genetic engineering
Retrieved from "https://wiki.riteme.site/w/index.php?title=Genetic_engineering&oldid=218362209"