Course 28.2Lesson 3 of 3
A transgenic animal carries a gene from another species. Almost all of them are mice, and each kind has its own use: to study genes, to model diseases, to make medicines, and to test vaccines and chemicals. This lesson lists the five uses with the examples that NCERT gives.
Try the code and the simulations beside the lesson.
A transgenic animal is an animal whose DNA has been manipulated so that it has and expresses an extra, foreign gene. Transgenic rats, rabbits, pigs, sheep, cows and fish have been made. But over 95 per cent of all the transgenic animals that exist are mice.
You may ask why scientists take the trouble to make them. NCERT gives five reasons.
Transgenic animals can be designed to show how genes are regulated and how they affect the normal work of the body and its development. NCERT's example is a study of complex factors such as insulin-like growth factor. Genes from other species that change the making of this factor are put in. Then the effects are studied, and this shows what the factor does in the body.
Many transgenic animals are made to increase our understanding of how genes help a disease to develop. They are models of human diseases, so that treatments can be investigated. Models exist for cancer, cystic fibrosis, rheumatoid arthritis and Alzheimer's disease.
Some medicines are, or contain, biological products, and these are often costly to make. A transgenic animal can make a useful product, if the gene for it is put in. NCERT gives these examples.
Transgenic mice are being developed to test the safety of vaccines before they are used on humans. They are used for the polio vaccine. If they prove reliable, they could replace monkeys in testing the safety of batches of the vaccine.
This is called toxicity testing. It is done in the same way as the test of a drug. Transgenic animals are made that carry genes that make them more sensitive to toxic substances than ordinary animals. They are exposed to the substance, and the effects are studied. The suitability of a chemical can then be decided in less time.
This part is not in the NEET syllabus, but A-Level and IB ask it. NCERT does not describe the method. The usual way is to inject the gene into a fertilised egg, and then to place the egg in the womb of a female. The animal that is born, if its cells carry the gene, is transgenic.
The first program works out the human protein in the milk of a cow. The second program counts the mice among a number of transgenic animals.
Try each one on your own first. If you are stuck, open a hint. Then check with Show the answer.
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