Recombinant human insulin (Humulin) was first produced commercially by Eli Lilly in 1983 by expressing the A chain (21 amino acids) and B chain (30 amino acids) separately in E. coli and assembling them via disulfide bonds. The C peptide connecting A and B chains in proinsulin is removed during maturation and is absent in the functional hormone. Gene therapy for ADA deficiency delivers a functional ADA gene via retroviral vector into the patient's isolated lymphocytes, but this is not a permanent cure; bone marrow transplant is required for permanence. PCR amplifies trace DNA for early HIV detection, ELISA detects antigens and antibodies via enzyme-color reactions, and autoradiography identifies specific nucleic acid sequences using radioactive probes. Bt cotton carries cry1Ac and cry2Ab genes targeting cotton bollworm, while Bt corn carries cry1Ab targeting the European corn borer, both lepidopteran pests. Cry proteins exist as inactive crystalline protoxins inside Bacillus thuringiensis and are only activated by the alkaline pH of an insect's midgut, where they form pores that lyse epithelial cells and kill the larva. RNAi in tobacco plants produces sense and antisense RNA that forms dsRNA inside the nematode Meloidogyne incognita, silencing its essential genes and controlling infection without chemical pesticides. Golden Rice was engineered for beta-carotene biosynthesis in the rice endosperm to combat vitamin A deficiency, while the Flavr Savr tomato was the first commercially approved GM food. Rosie, the first transgenic cow, produced milk enriched with human alpha-lactalbumin, and transgenic sheep produce alpha-1-antitrypsin in milk for emphysema treatment. India's GEAC regulates GMO approvals, and biopiracy cases involving neem, turmeric, and basmati rice have established important precedents for protecting traditional biological knowledge.