Definition: Transgenic animals are those that carry a foreign gene that has been deliberately inserted into their DNA and is passed on to the next generation.
Key Points: The inserted gene may come from the same species or a different species. The purpose is to alter traits, produce medically useful products, or study gene functions. The transgene becomes a permanent part of the animal’s genetic material and is inherited by its offspring.
Examples: Transgenic mice for studying cancer and genetic disorders. Transgenic cows that produce human proteins in milk. Transgenic pigs for organ transplantation research. Transgenic goats producing therapeutic proteins.
A compound (A) with molecular formula $C_4H_9I$ which is a primary alkyl halide, reacts with alcoholic KOH to give compound (B). Compound (B) reacts with HI to give (C) which is an isomer of (A). When (A) reacts with Na metal in the presence of dry ether, it gives a compound (D), C8H18, which is different from the compound formed when n-butyl iodide reacts with sodium. Write the structures of A, (B), (C) and (D) when (A) reacts with alcoholic KOH.