Biotechnology and its Applications

Key Concepts

Applications in Agriculture

Biotechnology provides alternatives to agro-chemical based agriculture and organic farming.

• Tissue Culture: Regenerating whole plants from explants (any part of a plant).
  • Totipotency: The capacity of a cell/explant to generate a whole plant.
  • Micro-propagation: Producing thousands of plants in short durations. Plants are somaclones (genetically identical).
  • Virus-free Plants: Obtained by culturing the meristem (apical/axillary), which remains free of virus even in infected plants.
  • Somatic Hybridisation: Fusion of isolated protoplasts from two different varieties (e.g., Pomato - tomato + potato).
• Genetically Modified Organisms (GMO): Plants, bacteria, fungi, and animals with altered genes.
  • Benefits: Abiotic stress tolerance, reduced pesticide reliance, reduced post-harvest losses, increased mineral usage efficiency, and enhanced nutritional value (e.g., Golden Rice - Vitamin A enriched).
• Bt Cotton:
  • Produced by Bacillus thuringiensis. Contains Bt toxin (coded by cry genes).
  • Toxin exists as inactive protoxins. Becomes active in the alkaline pH of the insect's gut, creating pores in the midgut and causing death.
  • cryIAc and cryIIAb control cotton bollworms; cryIAb controls corn borer.
• Pest Resistant Plants:
  • RNA Interference (RNAi): Cellular defense in eukaryotes. Silences specific mRNA using complementary dsRNA.
  • Used to protect tobacco plants from the nematode Meloidogyne incognita.

Applications in Medicine

• Genetically Engineered Insulin:
  • Earlier extracted from cattle/pigs (caused allergies).
  • Human Insulin: Consists of two chains (A and B) linked by disulphide bonds.
  • Eli Lilly (1983): Produced A and B chains separately in E. coli plasmids and combined them to form human insulin. (C-peptide is removed during maturation).
• Gene Therapy:
  • Correction of a gene defect in a child/embryo by delivering a normal gene.
  • ADA Deficiency (1990): First clinical gene therapy for a 4-year-old girl. Involves introducing functional ADA cDNA into the patient's lymphocytes using a retroviral vector.
• Molecular Diagnosis:
  • PCR: Detects very low concentrations of pathogens (e.g., HIV, mutations in cancer) by nucleic acid amplification.
  • ELISA: Based on antigen-antibody interaction.
  • Probes: Radioactive single-stranded DNA/RNA used to detect mutated genes via autoradiography.

Transgenic Animals

Animals with manipulated DNA (95% are mice).

• Reasons for Production:
  1. Study of normal physiology and development.
  2. Study of diseases (models for cancer, Alzheimer's, etc.).
  3. Biological products (e.g., Rosie, the first transgenic cow, produced milk with human alpha-lactalbumin).
  4. Vaccine safety testing (e.g., Polio vaccine).
  5. Chemical safety testing (toxicity testing).

Ethical Issues

• GEAC (Genetic Engineering Approval Committee): Indian organisation that regulates GM research and safety.
• Patents: Issues arise when companies patent resources used by indigenous people for centuries (e.g., Basmati Rice patent by a US company in 1997).
• Biopiracy: Use of bio-resources by MNCs without proper authorisation or compensation to the countries/people concerned.
• Indian Patents Bill: Includes provisions to prevent unauthorised exploitation of bio-resources and traditional knowledge.