Biotechnology and the Manipulation of Genes
Biotechnology and the Manipulation of Genes
Biotechnology and the Manipulation of Genes
Gene manipulation is a primary activity of biotechnology, a broad field that uses living organisms (or biological systems) to treat or modify both humans and the environment. Although we think of biotechnology as a futuristic technology, its practice began centuries ago when people began to breed animals and use yeast to make bread rise. Biotechnology encompasses genetic crop engineering, bioremediation (the use of biological organisms, often genetically modified, to ameliorate pollution and contamination of the environment), food processing, drug production, and proteomics (the study of all the proteins expressed by a genome, especially their physiological and pathophysiological functions).
A common technique in biotechnology is to manipulate genes in simple organisms, usually bacteria, to manufacture biochemicals that can be used for a variety of products, especially medicine. Unlike traditional drugs, biotechnology products can (in principle) be designed to the genomes of individual patients, producing more effective treatments with fewer side effects.
Biotechnology is also widely used in forensics. Using DNA “fingerprinting,” investigators can identify potential criminal suspects by analyzing DNA from as little as a strand of hair or trace of blood found at a crime scene.
Historical Background and Scientific Foundations
Humans have used biotechnology since prehistoric times to hybridize crops and breed animals with desired characteristics, practices that increased the likelihood that desired traits would be passed on to succeeding generations. People also used microorganisms to make bread rise, turn milk into yogurt and cheese, and produce alcoholic beverages. These lengthy and painstaking processes, however, are no longer the only way to pursue biotechnology. We can now “genetically engineer” animals and plants to obtain desired genetic traits and phenotypes.
Many striking advances in biotechnology have been in the field of medicine, especially since the discovery of microorganisms and proteins. English naturalist Charles Darwin (1809–1882) revolutionized thinking about species change and adaptation in biological organisms with the publication of On the Origin of Species in 1859; Austrian botanist Gregor Mendel (1822–1884) discovered the laws of heredity in 1865, setting the foundation for genetic research. In the late nineteenth century, French chemist Louis Pasteur (1822–1895) and German physician Robert Koch (1843–1910) made breakthrough discoveries in microbiology. All of these discoveries helped set the stage for the advent of modern biotechnology.
In the 1950s, using the technique of x-ray diffraction, American geneticist James Watson (1928–) and British biophysicist Francis Crick (1916–2004) revealed the double-helix structure of deoxyribonucleic acid (DNA), a discovery that created a biochemical basis for manipulating genetic traits. Another fundamental discovery by American biochemists Marshall Nirenberg (1927–) and Har Gobind Khorana (1922–) deciphered the DNA codons (nucleotide triplets) that compose the 20 amino acids found in living organisms. Shortly thereafter the manipulation of the genetic code of wheat by American agricultural scientist Norman Borlaug (1914–) made possible a 70% increase in crop yields.
As important as these were to the development of biotechnology, the discovery of restriction enzymes (an enzyme that can cut through the double strands of a DNA molecule) in 1970 were the new technology's first actual “tools.” Restriction enzymes allowed researchers to fragment a bacterium's genetic code and then insert genes from other organisms, allowing scientists to hijack the bacterium's genetic machinery and use it to produce recombinant DNA.
Human insulin was biotechnology's first important medical product. Although it had been possible to collect insulin from the pancreases of pigs and cows since the 1920s, some diabetics were allergic to insulin derived from animals. Researchers inserted a gene for insulin production into bacteria and cloned the bacteria with recombinant human DNA. With extensive cloning they were able to produce enough insulin to satisfy the growing demand.
Biotechnology in the Twenty-First Century
Today's biotechnological advances, especially those dealing with medical or cloning techniques, are frequently discussed in the popular press. The first mammal to be cloned was a sheep named Dolly, born in Scotland in 1997. Dolly was followed by another clone named Polly, created using “nuclear transfer technology,” in which some human genes were inserted into Polly's genome. At about the same time scientists created artificial human chromosomes and cloned rhesus monkeys.
Another aspect of biotechnology that has had extensive press coverage is the successful growth of and research into embryonic stem cells that began in 1998. Stem cells have the potential to develop into other types of body tissue cell (e.g., bone, muscle, skin), and molecular
biologists wanted to see if they could be used to repair injured human tissue. However, embryonic stem cell research generated controversy and some opposition because it destroys the embryos from which the stem cells are harvested. Adult stem cells have also shown considerable potential for transplantation and future therapies.
Yet another controversy arose with the creation of genetically modified foods. These are animals and plants that contain genes from other plants or animals (e.g., one venture inserted fish genes into tomatoes), increasing concern about their safety for human consumption.
In 1998 scientists assembled the complete genome of the nematode worm Caenorhabditis elegans, paving the way for the development of the procedures employed to assemble the human genome—a map that plots the genes on each chromosome. The human genome was compiled independently by American biologist J. Craig Venter (1946–) and American geneticist Francis Collins (1950–) in 2000.
The horticultural and agricultural sides of biotechnology have also seen dramatic advances. Molecular biology has been used to enhance plants in commercial production across the world. Such ventures require large investments, but investors hope to reap high profits because these new methods can provide better market positions for their products. For example, if products enhanced through biotechnology practices can withstand the rigors of shipping or resist spoilage better than competing products, they will have a competitive edge.
Modern Cultural Connections
Biotechnology's rise has spurred an equally dramatic rise in the press coverage of controversial topics. An editorial in the prominent British medical journal the Lancet called bioethics a cultural war zone in which disagreements are deep and often intractable, where enormous stakes regarding the future of mankind are being contested, and where authorities are sharply divided and diverse.
In addition to the sensitive topics of embryonic stem cells and cloning, much bioethical controversy stems from the uncertainty of emerging technologies. For example, if it becomes possible to extend life through the manipulation of genes, who should have access to this technology, which will undoubtedly be very expensive? If human beings can be enhanced genetically, which values should be served in doing so? For example, might “super warriors” or “super scholars” be created, in which a degree of specialization in subgroups of the population could go far beyond the current degree of human genetic variability?
Paradoxically, as biotechnology has adapted some food to the long-distance distribution systems that keep supermarkets bursting in the developed world, some
products, especially genetically enhanced varieties of corn, have been deemed less desirable because their taste or texture is inferior to locally grown varieties. Other types of genetically manipulated foods are rejected as “frankenfood”—products whose safety is unknown.
On the other hand, agricultural biotechnology may help solve previously intractable problems of hunger and malnutrition. A “doubly green revolution” could provide food for poor and marginalized populations. Genetic manipulation could increase agricultural yields in developing countries with the development of more sustainable crops. For example, disease- and pest-resistant fruits and vegetables with higher nutritional value (e.g., more iron, vitamin A, and protein) could improve the health of people in developing regions where the imbalanced indigenous diet is overly dependent on grains such as rice and corn.
Biotechnology researchers are also investigating animal and plant biodiversity in the tropics, where the uncontrolled extraction and biopiracy of natural products worries both governments and environmentalists. Nearly a quarter of all medicines and pharmaceutical products have their origin in tropical rain forests. The world market for such biotechnology-derived pharmaceuticals is approximately $500 billion. To tap into this growing market while preserving the natural resources that will sustain it, Brazil is establishing a new biotechnology center in Manaus at the heart of the Amazon River basin under the auspices of national and international partnership. Its primary goal will be to explore the region's biological wealth without destroying forests or disturbing its ecosystems.
Scientists will search for and extract bioactive molecules important in medicines, including “lifestyle drugs”; in agriculture, such as biopesticides; and in other products, such as cosmetics, body-care products, and perfumes. Such large-scale biotechnology projects could reinforce the commercial value of natural ecosystems, which generate enormous biodiversity and offer tremendous genetic wealth.
As with all other avenues of technological development, biotechnology inspires both great fear and high hopes. If the track record of human history is a guide to the future, some of each will be realized. The best outcome would be that humankind's impulse toward fairness and justice will overcome temptations to use biotechnology in the service of unjust and inhuman goals.
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Kenneth T. LaPensee