Biology · Biotechnology and Its Applications · NEET
An animal is transgenic only when a foreign gene (a transgene) from another species has been added to its DNA and the animal expresses that gene. NCERT definition: 'Animals that have had their DNA manipulated to possess and express an extra (foreign) gene are known as transgenic animals.' The key words are 'possess AND express' — the gene must be present and working, not just inserted.
No. A clone is a genetic copy of an existing animal, made without adding any new foreign gene (for example, Dolly the sheep). A transgenic animal has an extra foreign gene added to its DNA. Rosie the cow is transgenic because she carried a human gene, not because she was copied. NEET often mixes these two ideas, so keep them separate.
NCERT clearly states that although transgenic rats, rabbits, pigs, sheep, cows and fish exist, over 95 per cent of all existing transgenic animals are mice. Mice are used most because they breed fast, are small and cheap to keep, and serve as easy models for studying human genes and diseases like cancer, cystic fibrosis, rheumatoid arthritis and Alzheimer's. This '95% mice' fact is a favourite one-liner in NEET.
Yes, if the foreign gene is inserted into the germ-line (the cells that form eggs or sperm), the transgene is inherited by the offspring, so the trait is passed to the next generation. This is how a whole line of transgenic mice for one disease model is maintained.
NCERT names Rosie, the first transgenic cow, produced in 1997. Rosie's milk contained human alpha-lactalbumin (2.4 grams per litre) and was nutritionally more balanced for human babies than natural cow-milk. Do not confuse Rosie's milk protein (alpha-lactalbumin) with the emphysema drug protein alpha-1-antitrypsin — both appear in the same NCERT section.
The human protein named α-1-antitrypsin, obtained from transgenic animals, is used for the treatment of ______.
Try the real previous-year questions from this chapter — each with the answer and a full solution.
An animal whose DNA has been manipulated to possess and express an extra foreign gene from another organism. The foreign gene is called a transgene.
Mice. NCERT states that although rats, rabbits, pigs, sheep, cows and fish have been made transgenic, over 95 per cent are mice because they are small, breed fast and are good disease models.
Rosie (1997) was the first transgenic cow. Her milk contained human alpha-lactalbumin (2.4 g per litre), making it more balanced for human babies than normal cow-milk.
Study of normal physiology and development, study of disease, making biological products (like alpha-1-antitrypsin), vaccine safety testing, and chemical/toxicity safety testing.
Yes. Any organism whose genes have been altered by adding foreign DNA is a genetically modified organism (GMO). A transgenic animal is a GMO in animal form.
