Recombinant DNA, or rDNA, is DNA that is formed by combining DNA from different sources through a process called genetic recombination. Often, the sources are from different organisms. Generally speaking, DNA from different organisms has the same general chemical structure. For this reason, it is possible to create DNA from different sources by combining strands.
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Key Takeaways
- Recombinant DNA technology combines DNA from different sources to create a different sequence of DNA.
- Recombinant DNA technology is used in a wide range of applications from vaccine production to the production of genetically engineered crops.
- As recombinant DNA technology advances, technique precision must be balanced by ethical concerns.
Recombinant DNA has numerous applications in science and medicine. One well-known use of recombinant DNA is in the production of insulin. Prior to the advent of this technology, insulin largely came from animals. Insulin can now be produced more efficiently by using organisms like E. coli and yeast. By inserting the gene for insulin from humans in these organisms, insulin can be produced.
What Is DNA?
The Process of Genetic Recombination
In the 1970s, scientists found a class of enzymes that severed DNA in specific nucleotide combinations. These enzymes are known as restriction enzymes. That discovery allowed other scientists to isolate DNA from different sources and to create the first artificial rDNA molecule. Other discoveries followed, and today a number of methods for recombining DNA exist.
While several scientists were instrumental in developing these recombinant DNA processes, Peter Lobban, a graduate student under the tutelage of Dale Kaiser in the Biochemistry Department of Stanford University, is usually credited with being the first to suggest the idea of recombinant DNA. Others at Stanford were instrumental in developing the original techniques used.
While mechanisms can differ widely, the general process of genetic recombination involves the following steps.
- A specific gene (for example, a human gene) is identified and isolated.
- This gene is inserted into a vector. A vector is the mechanism by which the genetic material of the gene is carried into another cell. Plasmids are an example of a common vector.
- The vector is inserted into another organism. This can be achieved by a number of different gene transfer methods like sonication, micro-injections, and electroporation.
- After the introduction of the vector, cells that have the recombinant vector are isolated, selected, and cultured.
- The gene is expressed so that the desired product can eventually be synthesized, usually in large quantities.
Examples of Recombinant DNA Technology
Recombinant DNA technology is used in a number of applications including vaccines, food products, pharmaceutical products, diagnostic testing, and genetically engineered crops.
Vaccines
Vaccines with viral proteins produced by bacteria or yeast from recombined viral genes are considered to be safer than those created by more traditional methods and containing viral particles.
Other Pharmaceutical Products
As mentioned earlier, insulin is another example of the use of recombinant DNA technology. Previously, insulin was obtained from animals, primarily from the pancreas of pigs and cows, but using recombinant DNA technology to insert the human insulin gene into bacteria or yeast makes it simpler to produce larger quantities.
A number of other pharmaceutical products, like antibiotics and human protein replacements, are produced by similar methods.
Food Products
A number of food products are produced using recombinant DNA technology. One common example is the chymosin enzyme, an enzyme used in making cheese. Traditionally, it is found in rennet which is prepared from the stomachs of calves, but producing chymosin through genetic engineering is much easier and faster (and does not require the killing of young animals). Today, a majority of the cheese produced in the United States is made with genetically modified chymosin.
Diagnostic Testing
Recombinant DNA technology is also used in the diagnostic testing field. Genetic testing for a wide range of conditions, like cystic fibrosis and muscular dystrophy, have benefited from the use of rDNA technology.
Crops
Recombinant DNA technology has been used to produce both insect- and herbicide-resistant crops. The most common herbicide-resistant crops are resistant to the application of glyphosate, a common weed killer. Such crop production is not without issue as many question the long term safety of such genetically engineered crops.
The Future of Genetic Manipulation
Scientists are excited about the future of genetic manipulation. While techniques on the horizon differ, all have in common the precision with which the genome can be manipulated.
CRISPR-Cas9
One such example is CRISPR-Cas9. This is a molecule that allows for the insertion or deletion of DNA in an extremely precise manner. CRISPR is an acronym for “Clustered Regularly Interspaced Short Palindromic Repeats” while Cas9 is shorthand for “CRISPR associated protein 9”. Over the last several years, the scientific community has been excited about prospects for its usage. Associated processes are faster, more precise, and less expensive than other methods.
Ethical Questions
While much of the advances allow for more precise techniques, ethical questions are also being raised. For example, because we have the technology to do something, does that mean that we should do it? What are the ethical implications of more precise genetic testing, particularly as it relates to human genetic diseases?
From the early work by Paul Berg who organized the International Congress on Recombinant DNA Molecules in 1975, to the current guidelines set forth by The National Institutes of Health (NIH), a number of valid ethical concerns have been raised and addressed.
NIH Guidelines
The NIH guidelines, note that they “detail safety practices and containment procedures for basic and clinical research involving recombinant or synthetic nucleic acid molecules, including the creation and use of organisms and viruses containing recombinant or synthetic nucleic acid molecules.” The guidelines are designed to give researchers proper conduct guidelines for conducting research in this field.
Bioethicists contend that science must always be ethically balanced, so that advancement is beneficial to humankind, rather than harmful.
Sources
- Kochunni, Deena T, and Jazir Haneef. “5 Steps in Recombinant DNA Technology or RDNA Technology.” 5 Steps in Recombinant DNA Technology or RDNA Technology ~, www.biologyexams4u.com/2013/10/steps-in-recombinant-dna-technology.html.
- Life Sciences. “The Invention of Recombinant DNA Technology LSF Magazine Medium.” Medium, LSF Magazine, 12 Nov. 2015, medium.com/lsf-magazine/the-invention-of-recombinant-dna-technology-e040a8a1fa22.
- “NIH Guidelines – Office of Science Policy.” National Institutes of Health, U.S. Department of Health and Human Services, osp.od.nih.gov/biotechnology/nih-guidelines/.
