Ch 12 covers applications of biotechnology — in agriculture (Bt crops, pest-resistant GM plants), medicine (recombinant insulin, gene therapy, molecular diagnostics), transgenic animals, and the ethical/biosafety issues surrounding GMOs.
Bt crops: Bacillus thuringiensis cry genes (cry1Ac, cry2Ab for cotton bollworm). Cry protein forms pores in insect gut → death. Golden rice: β-carotene enriched. Recombinant insulin: pro-insulin from E. coli (A + B chains joined). Gene therapy: correct genetic defects — ADA deficiency (adenosine deaminase) first successful example. Molecular diagnostics: ELISA (antibody-based), PCR (DNA-based).
Transgenic animals: for studying gene regulation, testing vaccine safety, pharming (produce proteins in milk — e.g., α-1-antitrypsin). Biosafety issues: potential ecological risks of GMOs, biopiracy (using biodiversity without proper authorisation). Bioethics: regulations needed for genetic modification. GEAC (Genetic Engineering Appraisal Committee) in India.
Download: https://ncert.nic.in/textbook/pdf/lebo112.pdf | Complete book: https://ncert.nic.in/textbook/pdf/lebo1ps.zip
The cry protein (protoxin) produced by Bt is inactive in its original form. It gets activated only in the alkaline gut of certain insects (pH > 9.5), where it is cleaved to form active toxin that creates pores in the gut lining, causing cell swelling and lysis. Humans have acidic stomachs (pH ~2), so the protein is simply digested like any other protein — it is not activated and causes no harm.
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