Define transgenic animals. Explain in de | Class 12 Biology Chapter Biotechnology and its Application, Biotechnology and its Application NCERT Solutions

Genetic manipulation of animal cells or animals that have been permanently engineered by the gene insertion are known as transgenic animals and these contains functional foreign genes that have been introduced into the genome by genetic engineering. In 1981, Ralph Brinster and Richard Palmiter introduced first transgenic animal, by introducing a gene for rat growth hormone (GH) into fertilized eggs of mice. Using, recombinant DNA technology any foreign gene that are added to the target organism are known as transgene, which leads to modification in the gene expressions. They can be utilized in the several ways:

1. These transgenic are designed to increase study of how genes contribute to development of diseases and these are made to serve as the models for the human diseases like cancer, cystic fibrosis, Alzheimer etc. so that preventive measures are taken. For example: Transgenic Goats, they have human gene which codes for blood clot dissolving protein, i.e. Tissue plasminogen activator (TPA) is formed, secreted in milk. And, this is used for the treatment of coronary thrombosis disease. 
2. For the testing, the clinical trials and vaccine safety like, polio vaccine. The vast majority of transgenic experiments have been performed using the mice.
3. To improve human health, for enhancing nutrition, environment protection, to increase animal welfare and decrease livestock disease.
4. These can be used in the biological studies (gene mechanism and functions or by preparing recombinant proteins etc.).