What are transgenic animals? Explain briefly how the transgenic animals benefit the human beings.

Explanation

(i) To study normal physiology & development: Transgenic animals are used to study how genes are regulated, and how they affect the normal body functions and its development.
E.g. study of complex factors such as insulin-like growth factor. Genes (from other species) that alter the formation of this factor are intorduced and the biological effects are studied. This gives information about the biological role of the factor in the body.
(ii) To study the contribution of genes in the development of a disease: Transgenic models hepl for investigation of new treatments for human diseases. E.g. transgenic models for many human diseases such as cancer, cystic fibrosis, rheumatoid arthritis and Alzheimer.s.
(iii) Biological products: Some medicines contain biological products, but they are often expensice. Transgenic animals are used to produce useful biological products by introducing genes which codes for a particular product. E.g. human protein(`alpha` -1-antitrypsin) used to treat emphysema, products for treatment of phenylketonuria (PKU) and cystic fibrosis etc. In 1997, Rosie (first transgenic cow) produced human protein-enriched milk (2.4 gm per litre). It contains the human `alpha` -lactalbum and is nutritionally more balanced product for human babies than- natural cow-milk.
(iv) Vaccine safety testing: Transgenic mice are used to test the safety of the polio vaccine. If is found to be reliable, they can replace the use of monkeys to test the safety of batches of the vaccine.
(v) Chemical safety testing (toxicity testing): Transgenic animals are made that carry genes which make them more sensitive to toxic substances than non-transgenic animals. They are exposed to the toxic substances and the effects studied. It gives immediate results.