Learning Objectives
- Understand applications of biotechnology in agriculture, medicine, and industry
- Learn about transgenic organisms and Bt crops
- Study gene therapy and molecular diagnostics
- Understand bioethical concerns and biopiracy
Key Concepts
Biotechnology in Agriculture
Genetically Modified Organisms (GMOs): Organisms with altered genes through genetic engineering. Bt crops: Plants engineered with Bacillus thuringiensis cry genes. Bt cotton: Contains Cry1Ac and Cry2Ab genes — toxic to bollworm (lepidopteran pest). Bt corn: Contains Cry1Ab — toxic to corn borer. Cry protein (protoxin) is inactive; in alkaline insect gut → activated → binds to midgut epithelium → pores → cell lysis → insect death. Harmless to humans (our gut is acidic).
Pest-resistant plants: RNA interference (RNAi) used to create nematode-resistant tobacco. Complementary RNA silences specific mRNA → parasite gene is silenced. Golden Rice: Engineered with beta-carotene genes (provitamin A) to combat vitamin A deficiency. Flavr Savr tomato: First GM food approved (delayed ripening by antisense RNA technology).
Biotechnology in Medicine
Genetically Engineered Insulin: Humulin — human insulin produced in E. coli. Insulin gene (A chain = 21 amino acids, B chain = 30 amino acids) cloned separately into plasmids → expressed → chains combined with disulfide bonds. Eli Lilly (1983) was first to produce recombinant insulin commercially. Previously insulin was extracted from pancreas of slaughtered cattle/pigs (caused allergies).
Gene Therapy: Correction of genetic defects by inserting functional genes. First successful example: ADA (Adenosine Deaminase) deficiency — SCID (Severe Combined Immunodeficiency). Lymphocytes from patient → cultured → functional ADA gene inserted using retroviral vector → cells reintroduced. Not permanent cure; repeated treatments needed. Permanent cure: gene therapy in bone marrow cells.
Molecular Diagnostics: PCR: Amplifies pathogen DNA for early detection (HIV, tuberculosis). ELISA (Enzyme Linked Immunosorbent Assay): Detects antigens or antibodies using enzyme-linked antibodies. Used for HIV screening, pregnancy tests. Autoradiography / Southern blotting for DNA detection.
Transgenic Animals
Animals with foreign genes. Applications: (1) Study gene regulation and disease models (e.g., transgenic mice for cancer research), (2) Biological products (human protein alpha-1-antitrypsin in transgenic sheep milk — for emphysema treatment; Rosie — first transgenic cow produced human protein-enriched milk), (3) Vaccine safety testing, (4) Chemical safety testing (toxicity testing).
Ethical Issues
GEAC (Genetic Engineering Appraisal Committee): Indian regulatory body for GM research and safety. Decides validity of GM research and safety of GM organisms for public use. Biopiracy: Unauthorized use of bioresources and traditional knowledge by multinational companies. Examples: Neem (patented by European company), Turmeric (patent by University of Mississippi Medical Centre — revoked after India challenged), Basmati rice (patent by RiceTec Inc. USA). India passed Biodiversity Act, 2002 and Plant Variety Protection and Farmers' Rights Act to prevent biopiracy.
Summary
Biotechnology has transformed agriculture (Bt crops, pest-resistant plants), medicine (recombinant insulin, gene therapy, molecular diagnostics), and created transgenic animals for research. Ethical concerns include GMO safety, gene therapy ethics, and biopiracy. Regulatory bodies like GEAC oversee GM organism research and commercialization.
Important Terms
- Bt crops: Transgenic crops with Bacillus thuringiensis cry genes for insect resistance
- Gene therapy: Insertion of functional genes to correct genetic disorders
- Humulin: Recombinant human insulin produced in E. coli
- RNAi: RNA interference — gene silencing mechanism
- Transgenic animal: Animal with foreign gene integrated into its genome
- Biopiracy: Unauthorized exploitation of biological resources and traditional knowledge
- GEAC: Genetic Engineering Appraisal Committee — Indian regulatory body
- ADA deficiency: First genetic disorder treated by gene therapy
Quick Revision
- Bt cotton: Cry1Ac + Cry2Ab → kills bollworm (lepidopteran)
- Cry protein: protoxin → activated in alkaline insect gut → cell lysis
- Humulin: recombinant insulin in E. coli; A chain (21 aa) + B chain (30 aa)
- Gene therapy: ADA deficiency (SCID) — first successful case
- RNAi: nematode-resistant tobacco (complementary dsRNA silences parasite genes)
- Rosie: first transgenic cow (human protein in milk)
- Biopiracy examples: Neem, Turmeric, Basmati rice
- GEAC regulates GM research in India