Various types of bacteria produce restriction enzymes. They are useful as they have the ability to recognise a particular sequence of the chain of chemical units, called nucleotide bases.
Nucleotide bases hold sections of the DNA together; restriction enzymes cut the DNA at these locations.
The fragments produced in this way can be joined using other enzymes known as ligases.
“Also important in the manipulation of DNA are so-called vectors, which are pieces of NDA that can self-replicate independently of the DNA in the host cell in which they are grown.”
(Encarta – 98 Encyclopaedia- © 1993-1997)
Examples of such vectors include plasmids, viruses, and yeast artificial enzymes. These vectors permit the generation of multiple copies of a particular piece of DNA, allowing the production of sufficient quantities of material with which to work with.
This process is commonly known as “cloning”, because multiple copies of an identical molecule are produced.
What are its uses?
“Humans have used organisms for thousands of years. Plants were used for shelter, as tools, as food and as a source of medicine”.
(“A new introduction to biology” – Bill Indge, Martin Rowland, Margaret Baker)
As well as this humans also genetically changed these organisms. They did this by only allowing the strongest cattle, the best crop, and the fattest pigs, to breed, as a result more crops were harvested, and animals gave a higher yield of milk, wool, or meat. This process is known as artificial selection.
The use of recombinant DNA technology allows greater control over this genetic manipulation and has benefited humans in a much wider spectrum of ways.
The majority of the positive applications of genetic engineering , however, are in the field of medicine.
Genetic engineering can be used to produce large quantities of a normally rare protein. For example, human insulin and growth hormone, which are of great medical importance, have been produced in large amounts from bacterial cells containing appropriately engineered genes.
“In addition, genetic engineering can be used to investigate basic questions in biology, such as when and where a gene is expressed (transcribed) during development”.
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Genetic engineering and gene therapy (“A process of supplying a functional gene to cells lacking that function, with the aim of correcting a genetic disorder” - Encarta – 98 Encyclopaedia- © 1993-1997) is being used by researchers to diagnose and predict disease, and develop therapies and drugs to treat devastating diseases. These diseases include cancer, Alzheimer’s, diabetes, and cystic fibrosis.
Most of these tests however are still only being tested on animals,
“If you have cancer, and you’re a mouse, then I can cure you” says Chung Lee of Northwestern University in Illinois. “Of course, there’s a big leap between mice and humans. But it seems logical that this strategy would work for people too.”
(New Scientist- December 2002- By Nicola Jones, Boston)
Lots of products, however, have been engineered and are available for use by humans these include: -
- Insulin for diabetes.
- Factor VIII for males suffering from haemophilia A.
- Factor IX for haemophilia B.
- Human growth hormone (GH).
- Erythropoietin (EPO) for treating anaemia.
- Three types of interferon’s- fight viral infections.
- Several interleukins.
- Granulated-macrophage colony stimulating factor (GM-CSF) for stimulating the bone marrow after a bone marrow transplant.
- Tissue plasminogen activator (TPA) for dissolving blood clots.
- Adenosine deaminase (ADA) for treating some forms of severe combined immunodeficiency (SCID).
- Andiostatin and endostatin for trials as anti-cancer drugs.
- Parathyroid hormone.
What hazards are there?
Not everyone is happy about the use of recombinant DNA technology and genetic engineering.
“Over the past few years, there have been a number of demonstrations about the growth of genetically modified organisms (GMO’s).”
(“A new introduction to biology” – Bill Indge, Martin Rowland, Margaret Baker)
Consequently in most nations experiments with recombinant DNA are closely regulated.
Yet despite these safety checks, many people, including scientists and politicians, are concerned about the risks of recombinant DNA technology.
Many of the ‘test plots’ on which the genetically modified crops are grown are out in the open. If pollen or seeds from a genetically modified plant were carried by the wind away from the test plots, they could pollinate other plants and grow everywhere. Plus if one of the modifications was a resistance to ‘herbicides’ then the plants would be unstoppable and could severely disrupt our ecosystem.
Scientists are also working on transgenic bacteria and viruses, and if these were to mutate, they could create whole new pathogens, that we might not be able to control. Thus though meddling with nature we may bring about our own destruction.
There a numerous ethical implications of the use or this technology such as the objection to the use of certain transgenic organisms by certain religious groups.
“Many religious groups could not use products from specific organisms, because of the laws set out by their religion”
(“A new introduction to biology” – Bill Indge, Martin Rowland, Margaret Baker)
These would include Hindus, to whom which cows are sacred, and the Jews and Muslims, to whom pigs are unclean. The use of products from either of these sources might be unacceptable for people of these religions and thus prove completely useless.
Conclusion
In my personal opinion the process of genetic engineering has great potential, and could prove invaluable to the human race.
Yet while the potential benefits of genetic engineering could be considerable, so may be the potential dangers.
For example, the introduction of cancer-causing genes into a common infectious organism, such as influenza virus, could be very dangerous.
Plus despite all the stringent controls and meticulous testing, some unforeseen effect might occur as the result of genetic manipulation.
It is up to you whether you feel the “Pro’s” out way the “Con’s” for the long-term benefit of mankind.
BIBLIOGRAPHY
- A new introduction to biology” – Bill Indge, Martin Rowland, Margaret Baker.
- Encarta – 98 Encyclopaedia- © 1993-1997.
- New Scientist- December 2002- By Nicola Jones, Boston.
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Analysis of the types of knowledge and arguments I have used
