Genetic engineering, also known as gene splicing technology and DNA recombination technology, is based on molecular genetics, using modern methods of molecular biology and microbiology as means, constructing hybrid DNA molecules from different sources in vitro according to the pre-designed blueprint, and then introducing living cells to change the original genetic characteristics of organisms, obtain new varieties and produce new products. Genetic engineering is an important branch of bioengineering, which constitutes bioengineering together with cell engineering, enzyme engineering, protein engineering and microbial engineering. Genetic engineering is a complex technology to manipulate genes at the molecular level. It is the operation of introducing foreign genes into recipient cells through in vitro recombination, so that the genes can be replicated, transcribed, translated and expressed in recipient cells. Genetic engineering is widely used, mainly in transgenic animals and plants, environmental protection, the production of genetically engineered drugs and gene therapy. China can produce transgenic fish with fast growth rate, tolerance to harsh environment and good meat quality; Argentina produces transgenic cattle containing human growth hormone in milk; Sweet pepper with cucumber bacterial wilt resistance gene, tomato with fish cold resistance gene, potato with cucumber bacterial wilt resistance gene, and allergic transgenic soybean; The "super bacteria" produced by genetic engineering can devour and decompose a variety of substances that pollute the environment. Insulin is a specific drug for treating diabetes. For a long time, it can only be extracted from the pancreas of pigs, cattle and other animals. 100Kg pancreas can only extract 4-5g insulin, and its low yield and high price can be imagined. Introducing synthetic insulin gene into E.coli can produce 100g insulin per 2000L culture medium! Large-scale industrial production not only solves the problem of drug output that is more expensive than gold, but also reduces the price by 30%-50%! Interferon is simply a "panacea" for treating viral infections! It used to be extracted from human blood, and it takes 300L of blood to extract 1mg! Needless to say, its "precious" degree. Genetically engineered human interferon α-2b (Andafen) is the first domestically engineered human interferon α-2b in China, which has the functions of antivirus, inhibiting tumor cell proliferation and regulating human immune function. Widely used in the treatment of viral diseases and various tumors, it is currently recognized as the first choice drug for the treatment of viral diseases and the main drug for tumor biotherapy. Using the "DNA probe" designed and manufactured by genetic engineering to detect viral infections and genetic defects such as hepatitis virus is not only accurate, but also rapid. By introducing normal genes into patients with genetic diseases through genetic engineering, the pain of patients can be relieved at one time.