Once simply fodder for science fiction works, genetic engineering has become a very real and important aspect of modern science. The process is essentially inserting new genetic material into an existing genome to change the organism's expressed traits. The first successful genetic engineering took place in 1973 with bacteria, and the field has grown to have applications in different industries. The biggest examples of genetic engineering are seen in agriculture and medicine.
A well known use of genetic engineering is in agriculture, where genetically modified (GM) foods have caused controversy since their introduction in the 1990s. GM crops are classified into three generations. First generation crops are designed to produce pesticides and resist herbicides that are used to kill weeds. These are the crops currently sold as food. The second generation of GM crops is meant to produce a stronger and larger yield that is more resistant to damage from drought, cold, and salt and has more inherent nutritional value. The third generation of GM crops is for pharmaceutical usage.
The intended improvements to the crops reduce the need for chemical pesticides, as that quality is expressed in the plants themselves. The increased resistance to disease and adverse conditions will theoretically allow for an easier address of the imminent problem of feeding the growing world population. Due to the relative youth of GM foods, medical concerns have been expressed as it is currently unclear whether these foods will harm human consumers.
Modification in agriculture extends beyond the plants to animals as well. Some animals that are integral to agriculture are engineered to produce milk with specific proteins, while others are given growth hormones.
Genetic engineering has given rise to the production of synthetic substances that are naturally produced within an organism's body. Deficiencies can therefore be combated as genetically engineered proteins and hormones can be introduced to the body. These synthetic productions include insulin, albumin, growth hormones, antibodies, and vaccines. Vaccines have been redesigned from their traditional state, which required a weakened form of the targeted disease being injected into a patient's body. Genetically engineered vaccines, however, confer immunity without the risk of introducing the infectious agents. Similarly, gene therapy allows genes to be copied and replaced to treat disorders (such as immunodeficiency) related to genetic issues.
Human diseases are also more closely studied due to the advent of genetic engineering. Scientists are able to introduce forms of disease into other animals (often pigs and mice) to test cures. Targeted diseases include cancer, diabetes, anxiety, Parkinson's disease, heart disease, arthritis, and obesity. Anti-aging steps have also been tested by mice by manipulating the presence of telomerase, an enzyme involved in DNA replication.
Overall, genetic engineering, though controversial, has opened many doors for scientists and researchers as its applications are virtually boundless. Its ethical implications are hotly debated and its ultimate prevalence in the world cannot yet be predicted.
For further reading, see the following:
The Hope, Hype & Reality of Genetic Engineering, By John C. Avise
What is genetic engineering? from Physicians and Scientists for Responsible
Application of Science and Technology at http://www.psrast.org/whatisge.htm