CBSE · Class 12 · Biology · Biotechnology and its ApplicationsWhat are Transgenic Animals? Discuss the various ethical, biological, and practical reasons for producing transgenic animals, giving specific real-world examples for each use.

Introduction to Transgenic Animals\nAnimals whose DNA has been manipulated to possess and express an extra (foreign) gene are known as transgenic animals. Transgenic rats, rabbits, pigs, sheep, cows, and fish have been produced, though the vast majority of existing transgenic animals are mice. Scientists introduce foreign genes into these animals to study gene regulation, disease development, biological products, and chemical safety.

Reasons for Producing Transgenic Animals

1. Study of Normal Physiology and Development:

   • Transgenic animals serve as models to understand how genes are regulated and how they affect the normal functioning of the body and its development.
   • Example: Studying complex factors involved in growth such as insulin-like growth factor (IGF). By introducing genes from other species, researchers observe biological changes.

2. Study of Diseases:

   • Transgenic models are designed to increase our understanding of how genes contribute to the development of diseases. These serve as models for human diseases so that investigation of new treatments is made possible.
   • Example: Transgenic models exist for human diseases such as cancer, cystic fibrosis, rheumatoid arthritis, and Alzheimer's disease.

3. Biological Products:

   • Medicines required to treat certain human diseases can contain biological products, but producing them is often expensive. Transgenic animals can be made to produce useful biological products by introducing the portion of DNA (or genes) which codes for a particular product.
   • Example: Rosie, the first transgenic cow (produced in 1997), produced human protein-enriched milk (2.4 grams per litre). The milk contained the human alpha-lactalbumin and was nutritionally a more balanced product for human babies than natural cow milk.

4. Vaccine Safety:

   • Transgenic animals are being used to test the safety of vaccines before they are authorized for use on humans.
   • Example: Transgenic mice are currently used to test the safety of the polio vaccine. If successful and safe, this replaces the use of monkeys in laboratories.

5. Chemical Safety Testing (Toxicity Testing):

   • This is known as toxicity/safety testing. Procedures are similar to those used for testing toxicity of drugs. Transgenic animals are made that carry genes which make them more sensitive to toxic substances than non-transgenic animals.
   • Example: Exposure to toxic substances in transgenic animals yields results in much less time, aiding efficient regulation.

Ethical Issues\nManipulation of living organisms by human beings without adequate regulation can run into ethical concerns. Genetic modification of animals can cause unforeseen suffering, disrupt ecological balances, and raise moral questions about exploiting animal life for commercial or experimental gains.