Transgenic animals are produced by man. Explain any three ways in which such animals can be beneficial to humans.

− Normal physiology and development: to study how genes are regulated / how genes affect normal body function and its development / study of complex factors involved in growth such as insulin-like growth factor. − Study of disease: to study how genes contribute to the development of a disease / model animals help us to study many diseases such as cancer or cystic fibrosis or rheumatoid arthritis or Alzheimer’s / help us to investigate new treatment methods. − Biological products: To produce specific biological products / medicines / Medicines required to treat certain human diseases / produce human protein α- $\displaystyle 1$-antitrypsin (which treat emphysema) / treatment of phenylketonuria / medicine required for the treatment of cystic fibrosis / produce human protein (alpha lactalbumin) rich milk by Rosie cow (it is nutritionally more balanced for human babies) − Vaccine safety: transgenic mice being developed for use in testing safety of vaccines before they are used on humans / Transgenic mice are being used to test the safety of the polio vaccine / after testing on transgenic animals is successful and found reliable they could replace use of monkeys to test the safety of batches of vaccine. − Chemical safety testing: Transgenic animals are made to carry genes which make them more sensitive to toxic substances than non-transgenic animals. They are then exposed to the toxic substances and the effects studied.