Chapter 10: Biotechnology and its Applications | Summary

Genetically Modified Organisms (GMOs) are plants, bacteria, fungi, or animals whose genes have been altered by manipulation. GM plants provide tolerance to abiotic stresses like cold, drought, salt, and heat; reduce reliance on chemical pesticides through pest resistance; reduce post-harvest losses; increase efficiency of mineral usage; and enhance nutritional value, as seen in Vitamin A-enriched golden rice. GM technology also enables plants to supply alternative industrial resources such as starches, fuels, and pharmaceuticals.

Bt toxin, produced by Bacillus thuringiensis, is a key pest-resistance strategy. The cry genes (cryIAc, cryIIAb, cryIAb) encode insecticidal proteins that exist as inactive protoxins in the bacteria. Upon ingestion by insects, the alkaline gut pH activates the toxin, which binds to midgut epithelial cells, creates pores causing cell swelling and lysis, and kills the insect. Bt cotton, Bt corn, rice, tomato, potato, and soyabean are major examples. For nematode infestation, RNA interference (RNAi) is used — nematode-specific genes introduced via Agrobacterium vectors produce sense and anti-sense RNA that form dsRNA, silencing the nematode's mRNA and preventing parasite survival in transgenic host plants.

Recombinant DNA technology has revolutionised healthcare by enabling mass production of safe and effective therapeutic drugs. Because recombinant therapeutics are identical to human proteins, they do not induce unwanted immunological responses and are free from infection risks associated with products from non-human sources. Approximately 30 recombinant therapeutics have been approved for human use worldwide, with 12 being marketed in India.

Genetically engineered insulin was a landmark achievement. Previously, insulin was extracted from the pancreas of slaughtered cattle and pigs, causing allergic reactions in some patients. In 1983, Eli Lilly prepared two DNA sequences corresponding to insulin chains A and B, introduced them into E. coli plasmids, produced the chains separately, and combined them via disulfide bonds to form human insulin. This bypassed the challenge of producing mature insulin directly, since natural insulin arises from pro-insulin by removal of the C peptide.

Gene therapy is a collection of methods that allows correction of a gene defect diagnosed in a child or embryo by inserting a normal gene to compensate for the non-functional one. The first clinical gene therapy was administered in 1990 to a 4-year-old girl with adenosine deaminase (ADA) deficiency, a condition caused by deletion of the ADA gene that impairs immune function. Conventional treatments include bone marrow transplantation and enzyme replacement therapy, but neither is completely curative.

In ADA gene therapy, lymphocytes from the patient's blood are cultured outside the body, functional ADA cDNA is introduced via a retroviral vector, and the engineered lymphocytes are returned to the patient. Since these cells are not immortal, periodic infusions are required. A permanent cure would require introducing the ADA gene into cells at early embryonic stages from marrow cells.

Early and accurate diagnosis is vital for effective disease treatment. Conventional methods such as serum and urine analysis cannot detect pathogens before symptoms appear. Recombinant DNA technology, Polymerase Chain Reaction (PCR), and Enzyme Linked Immunosorbent Assay (ELISA) enable early detection even at very low pathogen concentrations.

PCR amplifies nucleic acids from pathogens or mutated genes and is routinely used to detect HIV in suspected AIDS patients and mutations in cancer-suspected patients. A radioactively tagged single-stranded DNA or RNA probe hybridises to its complementary DNA in a clone; mutated gene clones are identified via autoradiography because the probe lacks complementarity with the mutant. ELISA detects infection through antigen-antibody interactions, identifying pathogen antigens or antibodies produced against a pathogen.

Transgenic animals have had their DNA manipulated to carry and express a foreign gene. Over 95% of all transgenic animals are mice. They are used to study normal physiology and development — for example, studying insulin-like growth factor — and to serve as disease models for cancer, cystic fibrosis, rheumatoid arthritis, and Alzheimer's disease to facilitate the development of new treatments.

Transgenic animals also serve as bioreactors for producing useful biological products. In 1997, the transgenic cow Rosie produced human alpha-lactalbumin-enriched milk (2.4 g/L), offering better nutritional balance for human babies. Transgenic mice are used for vaccine safety testing, such as testing the polio vaccine, and for chemical safety (toxicology) testing, where their heightened sensitivity to toxic substances allows faster and more reliable results than conventional testing.

The manipulation of living organisms requires ethical standards to evaluate the morality of human activities that may help or harm living beings. Genetic modification can have unpredictable ecological effects when GMOs are introduced into ecosystems. India has established the Genetic Engineering Approval Committee (GEAC) to evaluate the validity of GM research and the safety of GM organisms for public services.

Biopiracy refers to the unauthorised use of bio-resources and traditional knowledge by multinational companies without proper authorisation or compensatory payment. Examples include the 1997 US patent on Basmati rice derived from Indian varieties and attempts to patent products based on traditional medicines like turmeric and neem. The Indian Parliament has cleared amendments to the Indian Patents Bill to counter such exploitation, addressing patent terms, emergency provisions, and research and development initiatives.

Chapter 10 demonstrates the profound impact of biotechnology on agriculture and medicine. Tissue culture, somatic hybridisation, and genetic modification have transformed crop improvement by increasing yields, reducing pesticide use, and enhancing nutritional value. In medicine, recombinant insulin, gene therapy, and molecular diagnostics like PCR and ELISA represent milestones in treating and detecting diseases. Transgenic animals have become essential tools for studying physiology, modelling diseases, producing biological products, and conducting safety tests.

From an examination perspective, this chapter is highly scoring and frequently tested. Board questions focus on Bt toxin mechanism, RNAi, ADA gene therapy, molecular diagnostics, insulin production by recombinant DNA technology, transgenic animals and their uses, and ethical issues including biopiracy and GEAC. Understanding the distinction between somaclones, GMOs, and transgenic organisms, as well as the specific cry genes and their targets, is essential for scoring full marks in both short and long answer questions.