After the gene has been now separated it has to be copied, which is cloning to get this much of it to actually make it possible to be used. The DNA sequence needs a Vector for this process, as it can not replicate on its own. Normally in biology a Vector is an agent that transports between to organisms, but in terms of recombinant DNA the vector is a carrier for the DNA sequence. A vector is a self-replicating DNA molecule for example a plasmid or viral DNA. Plasmids are like a DNA circle, which is found in bacteria for example in Escherichia coli. These plasmids used as vectors have to have a genetic marker on them so that they can actually be identified, a site where the restriction enzyme can make a cut and they have to replicate inside their host. As now a plasmid is taken and is cut with the same restriction enzyme then the DNA sequence is going to have the same sticky ends. To be able to recognize later on the plasmid, which has been prepared the plasmid carriers two genes inside itself. These genes inside the plasmid make the bacteria resistant against the antibiotics ampicillin and tetracycline. A recognition sequence lies within the tetracycline gene, where the restriction enzyme made a cut. The cut plasmid and sequence of DNA are put together. Naturally the complementary sticky ends (as mentioned before same restriction enzyme) are attracted to each other and then bonded by adding the enzyme DNA ligase. The recombinant plasmid is introduced into bacterial cells, by just adding the DNA to the bacterial, which picks it up through the terms of transformation. From this point on cloning of the ``new´´ plasmid starts as the bacteria is reproducing. To actually now be able to recognize the recombinant plasmid in the bacteria from the other bacteria, because not all of the bacteria picked the plasmid up a copy is taken from the bacteria cultures. The original culture is now tested on tetracycline. As mentioned above the tetracycline resistant gene has been taken apart by restriction enzyme at our new plasmid, because a recognition side lied within it. The only bacteria now reaction sensitive to tetracycline will contain the recombinant DNA. As a copy of the original cultures has been taken before the bacteria containing the new DNA is identified and can be cloned by DNA replication.
The DNA in the bacteria can now be used in different ways depending on, which DNA sequence, vector and place to introduce it to have been chosen.
Recombinant DNA technology has been used in our every daily life, where sometimes our life even is dependent on it. Recombinant DNA has been introduced to bacteria, plants and even animals.
Medicine is highly depended on this technology as many diseases were able to be treating through this method. For example in some children and young people the Human growth hormone (hGH) is failed to secrete sufficiently leading to pituitary dwarfism. Normally the hormone is produced in the pituitary gland. The hormone is then circulated around the body stimulating the cells to grow, especially these of the skeleton. The problem can be cured by a series of injection of hGH. Unfortunately research has shown that getting the hormone of other animals, like sheep does not work or is not efficient enough. The hormone can be produced through recombinant DNA as the gene has been identified coding for the hormone. A plasmid is put together with the gene and introduced into the E. coli bacteria. As the hGH is a very simple gene, just consisting out of 14 amino acids it is actually easier to manufacture an artificial gene coding for the hormone. The vector in this case is the plasmid of the E. coli bacteria and the host is then the bacteria itself. This mutant of the E. coli is surviving under special laboratory conditions, where it is producing large number of hGH polypeptide, which then help to cure pituitary dwarfism.
Not only is the medicine taking benefit of the technology. As well the industry is using recombinant DNA technology to manipulate animals to make them more attractive as pets. In 1999 Dr. Zhinyuan Gong of the National University of Singapore extracted the green fluorescent protein (GFP) into the zeprafish genome. The protein is a natural produced green bioluminescence from a jellyfish. The fish is as well able to fertilize. At first the experiment was for developing a fish detecting pollution, but already in 2003 the trademarked protected fish called ``GloFish´´ went on the Taiwan market for $18.60 each. In December 2003 the fish was allowed to be sold in the US as well, as the firm of GloFish made various experiments and there was and is apparently no danger from a fish, which contains recombinant DNA (statement of the Glofish firm). Until now the fish is not allowed in Europe, because it is containing recombinant DNA or it is genetically modified.
Overall Recombinant DNA Technology is a great way to discover a lot of things, because there is just so much to actually experiment with. My opinion is that the development of this technology should not stop. Scientist should be allowed to research for things that could be beneficial to the human kind, but everything has to be controlled and serious. No messing around with genes, like I think the GloFish is.
Sources
"Troubled waters: fluorescent fish spark GM row" by A. Gumbel, May 4th, , London, England
``Biology for the IB DIPLOMA´´ Chris Clegg 2007, fist published in 2007 by Hodder Murray
``Senior Biology 1´´ 2008 Student Workbook, Richard Allan 2007, published by BIOZONE International Ltd
Word count: 1407
