Biotechnology and its Applications

Biotechnology has transformed agriculture by creating genetically modified (GM) crops — plants whose genes have been deliberately altered. The benefits are heavily examined: GM crops can be made more tolerant of abiotic stresses (cold, drought, salt, heat), more pest-resistant (reducing chemical pesticide use), more efficient in mineral use, less prone to post-harvest losses, and more nutritious — the classic example being golden rice, engineered to be rich in vitamin A.

The most important agricultural example is the Bt crop. The bacterium Bacillus thuringiensis makes a protein, the Bt toxin, that kills certain insect larvae. The genes coding for it are called cry genes: for instance, cryIAc and cryIIAb control the cotton bollworms and cryIAb controls the corn borer. By inserting the appropriate cry gene into cotton, scientists created Bt cotton, which makes its own insecticidal protein.

The way the Bt toxin works is a favourite NEET question. The toxin is produced as an inactive protoxin (a crystal protein) — this is why Bacillus itself is not killed. When an insect eats it, the alkaline pH of the insect's gut converts the protoxin into the active toxin. The active toxin then binds to the surface of the midgut epithelial cells and creates pores, causing the cells to swell, lyse (burst) and the insect to die.

Another elegant method makes plants pest-resistant using RNA interference (RNAi) — a natural cellular defence that silences specific mRNA using complementary double-stranded RNA (dsRNA). To protect tobacco from the nematode Meloidogyne incognita, genes producing both sense and antisense RNA against a nematode gene were introduced; the resulting dsRNA silences the nematode's mRNA, so the parasite cannot survive in the transgenic plant. For NEET, fix the benefits of GM crops (golden rice = vitamin A), the Bt mechanism (cry genes; protoxin → activated in alkaline insect gut → pores → death) and RNAi-based nematode resistance.

Biotechnology has given medicine safer drugs, gene-based cures and powerful diagnostics. The first triumph was genetically engineered (recombinant) human insulin. Insulin from animals (pig/cattle) caused allergies in some patients, so a human version was needed. Mature insulin has two short chains, A and B, linked by disulphide bonds; in the body it is first made as a longer prohormone (proinsulin) with an extra stretch called the C-peptide that is removed during maturation. The company Eli Lilly introduced the DNA sequences for the A and B chains separately into E. coli, which produced the two chains; these were then extracted and joined by disulphide bonds to make functional human insulin, marketed as Humulin.

A second application is gene therapy — correcting a gene defect by inserting a normal functional gene into a patient's cells. The first gene therapy (1990) was given to a girl with ADA (adenosine deaminase) deficiency, a severe immune disorder. Lymphocytes carrying a functional ADA gene were grown and returned to her body; because these cells are not permanent, the treatment had to be repeated periodically. A permanent cure would require introducing the gene into cells at an early embryonic stage.

The third application is molecular diagnosis — detecting a disease early and accurately, often before symptoms appear, when the pathogen or abnormality is present only in very small amounts. PCR (polymerase chain reaction) can amplify even tiny amounts of nucleic acid, so it can detect pathogens (such as HIV in suspected AIDS patients or mutations in suspected cancers) very early.

The other key tool is ELISA (enzyme-linked immunosorbent assay), based on the antigen–antibody interaction; it detects the presence of a pathogen by identifying the antigens it makes or the antibodies the body produces against it. Together with techniques like recombinant DNA probes, these give very early, sensitive detection. For NEET, fix recombinant insulin (A & B chains in E. coli, Humulin; mature insulin lacks the C-peptide), gene therapy (first for ADA deficiency, 1990), and the two diagnostics — PCR (amplifies nucleic acid, early detection) and ELISA (antigen–antibody).

A transgenic animal is an animal whose genome has been altered by introducing a foreign (manipulated) gene. Many such animals — mostly mice, but also rats, rabbits, pigs, cows and sheep — have been produced, and they serve several valuable purposes that are commonly asked.

First, transgenic animals help in the study of normal physiology and development: by adding or altering genes (for example genes regulating body growth), scientists learn how those genes control development and physiological processes. Second, they are used to study diseases: animals are designed to carry genes that make them develop human diseases (such as cancer, cystic fibrosis, rheumatoid arthritis or Alzheimer's), so that new treatments can be tested.

Third, and very importantly, transgenic animals are used to make biological products — valuable proteins that are otherwise costly to produce. A famous example is the first transgenic cow, 'Rosie' (1997), which produced human-protein-enriched milk containing the human protein alpha-lactalbumin, making the milk more nutritionally balanced for human babies. Such 'biological factories' can yield medicines like the human protein α-1-antitrypsin (used to treat emphysema).

Fourth, transgenic animals are used for vaccine safety testing (testing the safety of vaccines before they are used on humans — transgenic mice are being used to test the safety of the polio vaccine) and for chemical safety testing (toxicity testing), where transgenic animals carrying genes that make them more sensitive to toxic substances allow quicker results. So transgenic animals advance research, medicine and safety testing. For NEET, fix the definition and the four main uses — study of physiology/development, study of disease, production of biological products (Rosie cow, α-lactalbumin; α-1-antitrypsin), and vaccine/chemical safety testing.

The power to manipulate genes raises serious ethical, social and legal issues, which the chapter ends with. Genetic modification of organisms can have unpredictable results when they are introduced into the ecosystem, and there are moral concerns about modifying living things and patenting life. Because of this, every country needs to evaluate the safety of introducing GMOs.

In India this is the job of the GEAC (Genetic Engineering Approval Committee, now Appraisal Committee). The GEAC makes decisions on the validity and safety of GM research and the introduction of GM organisms for public use; no GMO can be released without its approval. This provides a regulatory check before any genetically engineered organism reaches the field or the market.

A major issue is biopiracy — the use of bio-resources by multinational companies and organisations without proper authorisation from the countries and people concerned, and without fair compensation (benefit-sharing). Industrialised nations are often rich in technology but poor in biodiversity, while developing nations like India are rich in biodiversity and traditional knowledge about its uses — and this knowledge has sometimes been exploited.

Classic examples are the foreign patents granted on traditional Indian resources: the Basmati rice, the neem tree, and the wound-healing properties of turmeric (haldi) — cases that were challenged because the knowledge was already part of India's traditional heritage. To prevent such unauthorised exploitation, the Indian Parliament amended the Indian Patents Bill to take such issues into account. For NEET, fix the role of GEAC (approves/regulates GMOs in India), the meaning of biopiracy, and the well-known patent examples (Basmati, neem, turmeric).