Transgenic Animals
மரபணு மாற்றப்பட்ட விலங்குகள்
Do not confuse transgenic animals with simple selective breeding. Transgenic animals involve the deliberate introduction of foreign DNA into the genome, creating a permanent alteration in the germline. If you cannot distinguish between recombinant DNA technology and traditional hybridization, you will lose marks on the application-based questions.
The idea
Transgenic animals are organisms whose genome has been altered by the introduction of an extra foreign gene. This gene is expressed to produce a specific phenotypic trait. Scientists use these models to study gene regulation, disease progression, and the efficacy of new vaccines. Furthermore, they are engineered to produce biological products like human proteins for medical therapy.
Why it matters
They serve as controlled biological models to understand human disease mechanisms and test the safety of medical treatments without direct human risk.
NEET lens
NEET focuses on the 'Why' of transgenic animals: physiology, disease models, and biological products. Memorize the example of 'Rosie', the transgenic cow that produced human alpha-lactalbumin-enriched milk. Do not fall for traps equating transgenic animals with simple cloning; focus on the 'foreign gene' aspect.
Clinical significance
Transgenic models are critical for studying human diseases like Alzheimer's, cancer, and cystic fibrosis. Without these models, testing the safety of vaccines like the polio vaccine would be impossible before human trials. Failure to use these models leads to unpredictable side effects in clinical pharmacology.
Introduction
Animals that have had their DNA manipulated to possess and express an extra (foreign) gene are known as transgenic animals.
Core concept
Examples: transgenic rats, rabbits, pigs, sheep, cows and fish have been produced, although over 95 per cent of all existing transgenic animals are mice. Uses (NCERT): (i) normal physiology and development — studying how genes are regulated; (ii) study of disease — models for human diseases such as cancer, cystic fibrosis, rheumatoid arthritis and Alzheimer's; (iii) biological products — e.g. transgenic animals producing human protein alpha-1-antitrypsin used to treat emphysema; in 1997, the first transgenic cow, Rosie, produced human protein-enriched milk (2.4 grams per litre) containing human alpha-lactalbumin, nutritionally a more balanced product for human babies than natural cow milk; (iv) vaccine safety — transgenic mice are being developed for testing the safety of vaccines (e.g. polio vaccine) before use on humans; (v) chemical safety testing (toxicity testing) — animals made more sensitive to toxic substances.
Go deeper
Transgenic animals can give results in less time than non-transgenic animals in toxicity testing, because they are made more sensitive.
From Class 10
Scientists can add a human gene to an animal like a cow so that its milk contains a useful human protein.