17.1E: Genetic Engineering
- Discuss how genetic engineering leads to DNA modification.
Genetic Engineering
Genetic engineering is the alteration of an organism’s genotype using recombinant DNA technology to modify an organism’s DNA to achieve desirable traits. Recombinant DNA technology, or DNA cloning, is the process of transferring a DNA fragment of interest from one organism to a self-replicating genetic element, such as a bacteria plasmid, which is called a vector. The DNA of interest can then be propagated in another organism. The addition of foreign DNA in the form of recombinant DNA vectors generated by molecular cloning is the most common method of genetic engineering. The organism that receives the recombinant DNA is called a genetically-modified organism (GMO). If the foreign DNA that is introduced comes from a different species, the host organism is called transgenic. Bacteria, plants, and animals have been genetically modified since the early 1970s for academic, medical, agricultural, and industrial purposes. In the US, GMOs such as Roundup-ready soybeans and borer-resistant corn are part of many common processed foods.
Gene Targeting
Although classical methods of studying the function of genes began with a given phenotype and determined the genetic basis of that phenotype, modern techniques allow researchers to start at the DNA sequence level and ask: “What does this gene or DNA element do? ” This technique, called reverse genetics, has resulted in reversing the classic genetic methodology. This method would be similar to damaging a body part to determine its function. An insect that loses a wing cannot fly, which means that the function of the wing is flight. The classical genetic method would compare insects that cannot fly with insects that can fly, and observe that the non-flying insects have lost wings. Similarly, mutating or deleting genes provides researchers with clues about gene function. The methods used to disable gene function are collectively called gene targeting. Gene targeting is the use of recombinant DNA vectors to alter the expression of a particular gene, either by introducing mutations in a gene, or by eliminating the expression of a certain gene by deleting a part or all of the gene sequence from the genome of an organism.
Key Points
- A genetically modified organism receives recombinant DNA generated through molecular cloning.
- Transgenic host organisms receive their foreign DNA from a different species.
- The use of recombinant DNA vectors to alter the expression of a particular gene is known as gene targeting, which is done through the addition of mutations in a gene or the exclusion of the expression of a certain gene.
- Recombinant DNA technology involves transferring a DNA fragment of interest from one organism to another by inserting it into a vector.
Key Terms
- recombinant DNA : DNA that has been engineered by splicing together fragments of DNA from multiple species and introduced into the cells of a host
- genetic engineering : the deliberate modification of the genetic structure of an organism
- genetically modified organism : an organism whose genetic material has been altered using genetic engineering techniques