Biotechnology and its Applications — Long Notes
Biotechnology impacts our lives through three main areas: agriculture, medicine, and environmental biotech. This chapter surveys concrete examples where genetic engineering has produced better crops, medicines, and diagnostics.
1. Biotechnology in Agriculture
1.1 Three Options for Increasing Food Production
- Agrochemically-based agriculture — heavy use of fertilisers and pesticides (fuels the Green Revolution but polluted soil and water).
- Organic farming — no synthetic chemicals; sustainable but often lower yield.
- Genetically engineered (GM) crop-based agriculture — modify plants directly for desired traits.
1.2 Advantages of GM Plants
- Resistance to abiotic stresses (cold, drought, salt, heat).
- Reduced reliance on chemical pesticides.
- Reduced post-harvest losses (e.g. FlavrSavr tomato).
- Improved efficiency of mineral usage.
- Enhanced nutritional value (e.g. Golden Rice with vitamin A precursor β-carotene).
- Novel products such as biofuels, medicines.
1.3 Bt Cotton
- Bacillus thuringiensis (Bt) is a soil bacterium that produces crystalline (Cry) proteins during its sporulation stage.
- Cry proteins are inactive as protoxin in the bacterium. Once ingested by an insect, the alkaline pH of the insect gut solubilises the crystal, activating the toxin.
- Active toxin binds the surface of gut cells, creates pores → osmotic imbalance → gut lysis → insect death.
- Different cry genes produce toxins specific to different insect groups:
- cryIAc, cryIIAb — cotton bollworms.
- cryIAb — corn borer.
- The cryIAc / cryIIAb genes were isolated and transferred into cotton — resulting Bt cotton is protected from cotton bollworms without needing insecticide sprays.
1.4 Pest-Resistant Plants via RNA Interference
- Meloidogyne incognita — a parasitic root-knot nematode that reduces yields of tobacco.
- Approach: RNA interference (RNAi) — a form of post-transcriptional gene silencing.
- Double-stranded RNA (dsRNA) complementary to the nematode's mRNA is produced in the host plant.
- When the nematode feeds, it takes in these dsRNA/siRNA molecules.
- The dsRNA silences a vital gene of the nematode → the parasite cannot survive.
- Delivery: gene encoding the nematode-specific dsRNA is introduced into tobacco via Agrobacterium tumefaciens (a natural plant transformation vector).
- Result: transgenic tobacco resistant to Meloidogyne.
2. Biotechnology in Medicine
2.1 Recombinant (Genetically Engineered) Insulin
- Diabetes is treated with insulin injections.
- Traditional source: insulin extracted from pancreatic glands of slaughtered cattle and pigs. This caused allergic reactions in some patients.
- Human insulin structure:
- Two chains — A (21 amino acids) and B (30 amino acids).
- Linked by two disulfide bridges between cysteines.
- Naturally, insulin is synthesised as pre-proinsulin, which loses its signal peptide → proinsulin (contains A, B, and a C-peptide connecting them). The C-peptide is cleaved to give mature insulin.
- In 1983, Eli Lilly produced recombinant insulin ("humulin") as follows:
- Chemically synthesised two DNA sequences corresponding to A and B chains.
- Introduced them into plasmids of E. coli separately.
- Bacteria produced chains A and B.
- Chains isolated, purified, joined via disulfide bonds → mature insulin.
- Human insulin from E. coli is now the standard therapy — no allergic reactions.
2.2 Gene Therapy
Gene therapy is a way of correcting a genetic defect by introducing a normal, functional copy of the gene into affected cells.
- Landmark: 1990 — a 4-year-old girl with SCID (Severe Combined Immunodeficiency) due to adenosine deaminase (ADA) deficiency received gene therapy.
- Procedure:
- Lymphocytes isolated from her blood.
- Functional ADA gene inserted via a retroviral vector.
- Modified lymphocytes returned to the patient.
- Downside: mature lymphocytes are short-lived → periodic infusions needed.
- Permanent cure requires introducing the ADA gene into bone marrow stem cells so all future lymphocytes carry the fix.
2.3 Molecular Diagnosis
Early, precise diagnosis is crucial. Molecular tools work at the DNA/RNA/protein level, often before clinical symptoms:
- PCR — amplifies pathogen DNA → detects HIV (before antibodies appear), tuberculosis, mutations linked to cancer. Also used in prenatal diagnostics.
- ELISA (Enzyme-Linked Immunosorbent Assay) — detects antigens or antibodies; standard HIV diagnostic.
- DNA probes and hybridisation — identify specific sequences (mutations, pathogen DNA).
3. Transgenic Animals
Animals whose genome has been altered by adding foreign genes.
Purposes and examples:
- Study normal physiology and disease — e.g. transgenic mice with human genes for insulin/Alzheimer's proteins.
- Biological products — transgenic sheep produce human α-1-antitrypsin in milk (used to treat emphysema).
- Vaccine safety testing — transgenic mice with polio virus receptors replace monkeys for polio vaccine testing.
- Chemical safety testing (toxicity testing) — transgenic animals more accurately model human responses.
Rosie (1997) was the first transgenic cow producing human α-lactalbumin-enriched milk — 2.4 g/L — making it more nutritionally balanced for human infants.
4. Ethical Issues
Some concerns raised by biotechnology:
- Long-term ecological impacts of GMOs.
- "Playing God" concerns.
- Ownership of biological resources and traditional knowledge.
- Access and equity in medicine.
GEAC — Genetic Engineering Approval Committee — is the Indian regulatory body that examines validity, safety, and ethical implications of GMO research and use.
5. Biopiracy
Biopiracy = use of bio-resources by multinational companies and other organisations without proper authorisation from countries and people who have traditionally used them, without compensating the source countries.
- Industrialised nations often hold the patents and profits; developing nations bear the resource cost.
- Traditional knowledge and land races collectively developed over generations get patented by outsiders.
Famous cases:
- Turmeric patent in the US (revoked after CSIR opposed).
- Basmati rice patent (partially revoked).
- Neem patent in Europe (revoked).
India passed the Indian Patents Bill (Second Amendment) to address biopiracy and TRIPS obligations while protecting local knowledge and biodiversity. It also has the Biological Diversity Act (2002) and access-benefit sharing rules.
Key take-aways
- Bt cotton protects itself against bollworms because Cry protoxin activates only in the alkaline insect gut — a beautiful case of selective toxicity.
- RNAi is a natural cellular immune system against foreign RNA — biotechnologists exploit it for pest resistance (e.g. tobacco vs Meloidogyne).
- Recombinant insulin (humulin) ended the shortage and allergy problems of animal-derived insulin. Two chains synthesised in E. coli then joined.
- Gene therapy in ADA-SCID was the first proof-of-concept; bone-marrow-based therapy is the aspirational permanent cure.
- Molecular diagnostics (PCR + ELISA) detect diseases before symptoms.
- Transgenic animals contribute to research, therapeutics (Rosie, α-1 antitrypsin sheep), and vaccine testing.
- GEAC oversight and biopiracy laws protect people, biodiversity, and traditional knowledge from misuse.
Biotechnology and its Applications — Long Notes
Biotechnology impacts our lives through three main areas: agriculture, medicine, and environmental biotech. This chapter surveys concrete examples where genetic engineering has produced better crops, medicines, and diagnostics.
1. Biotechnology in Agriculture
1.1 Three Options for Increasing Food Production
- Agrochemically-based agriculture — heavy use of fertilisers and pesticides (fuels the Green Revolution but polluted soil and water).
- Organic farming — no synthetic chemicals; sustainable but often lower yield.
- Genetically engineered (GM) crop-based agriculture — modify plants directly for desired traits.
1.2 Advantages of GM Plants
- Resistance to abiotic stresses (cold, drought, salt, heat).
- Reduced reliance on chemical pesticides.
- Reduced post-harvest losses (e.g. FlavrSavr tomato).
- Improved efficiency of mineral usage.
- Enhanced nutritional value (e.g. Golden Rice with vitamin A precursor β-carotene).
- Novel products such as biofuels, medicines.
1.3 Bt Cotton
- Bacillus thuringiensis (Bt) is a soil bacterium that produces crystalline (Cry) proteins during its sporulation stage.
- Cry proteins are inactive as protoxin in the bacterium. Once ingested by an insect, the alkaline pH of the insect gut solubilises the crystal, activating the toxin.
- Active toxin binds the surface of gut cells, creates pores → osmotic imbalance → gut lysis → insect death.
- Different cry genes produce toxins specific to different insect groups:
- cryIAc, cryIIAb — cotton bollworms.
- cryIAb — corn borer.
- The cryIAc / cryIIAb genes were isolated and transferred into cotton — resulting Bt cotton is protected from cotton bollworms without needing insecticide sprays.
1.4 Pest-Resistant Plants via RNA Interference
- Meloidogyne incognita — a parasitic root-knot nematode that reduces yields of tobacco.
- Approach: RNA interference (RNAi) — a form of post-transcriptional gene silencing.
- Double-stranded RNA (dsRNA) complementary to the nematode's mRNA is produced in the host plant.
- When the nematode feeds, it takes in these dsRNA/siRNA molecules.
- The dsRNA silences a vital gene of the nematode → the parasite cannot survive.
- Delivery: gene encoding the nematode-specific dsRNA is introduced into tobacco via Agrobacterium tumefaciens (a natural plant transformation vector).
- Result: transgenic tobacco resistant to Meloidogyne.
2. Biotechnology in Medicine
2.1 Recombinant (Genetically Engineered) Insulin
- Diabetes is treated with insulin injections.
- Traditional source: insulin extracted from pancreatic glands of slaughtered cattle and pigs. This caused allergic reactions in some patients.
- Human insulin structure:
- Two chains — A (21 amino acids) and B (30 amino acids).
- Linked by two disulfide bridges between cysteines.
- Naturally, insulin is synthesised as pre-proinsulin, which loses its signal peptide → proinsulin (contains A, B, and a C-peptide connecting them). The C-peptide is cleaved to give mature insulin.
- In 1983, Eli Lilly produced recombinant insulin ("humulin") as follows:
- Chemically synthesised two DNA sequences corresponding to A and B chains.
- Introduced them into plasmids of E. coli separately.
- Bacteria produced chains A and B.
- Chains isolated, purified, joined via disulfide bonds → mature insulin.
- Human insulin from E. coli is now the standard therapy — no allergic reactions.
2.2 Gene Therapy
Gene therapy is a way of correcting a genetic defect by introducing a normal, functional copy of the gene into affected cells.
- Landmark: 1990 — a 4-year-old girl with SCID (Severe Combined Immunodeficiency) due to adenosine deaminase (ADA) deficiency received gene therapy.
- Procedure:
- Lymphocytes isolated from her blood.
- Functional ADA gene inserted via a retroviral vector.
- Modified lymphocytes returned to the patient.
- Downside: mature lymphocytes are short-lived → periodic infusions needed.
- Permanent cure requires introducing the ADA gene into bone marrow stem cells so all future lymphocytes carry the fix.
2.3 Molecular Diagnosis
Early, precise diagnosis is crucial. Molecular tools work at the DNA/RNA/protein level, often before clinical symptoms:
- PCR — amplifies pathogen DNA → detects HIV (before antibodies appear), tuberculosis, mutations linked to cancer. Also used in prenatal diagnostics.
- ELISA (Enzyme-Linked Immunosorbent Assay) — detects antigens or antibodies; standard HIV diagnostic.
- DNA probes and hybridisation — identify specific sequences (mutations, pathogen DNA).
3. Transgenic Animals
Animals whose genome has been altered by adding foreign genes.
Purposes and examples:
- Study normal physiology and disease — e.g. transgenic mice with human genes for insulin/Alzheimer's proteins.
- Biological products — transgenic sheep produce human α-1-antitrypsin in milk (used to treat emphysema).
- Vaccine safety testing — transgenic mice with polio virus receptors replace monkeys for polio vaccine testing.
- Chemical safety testing (toxicity testing) — transgenic animals more accurately model human responses.
Rosie (1997) was the first transgenic cow producing human α-lactalbumin-enriched milk — 2.4 g/L — making it more nutritionally balanced for human infants.
4. Ethical Issues
Some concerns raised by biotechnology:
- Long-term ecological impacts of GMOs.
- "Playing God" concerns.
- Ownership of biological resources and traditional knowledge.
- Access and equity in medicine.
GEAC — Genetic Engineering Approval Committee — is the Indian regulatory body that examines validity, safety, and ethical implications of GMO research and use.
5. Biopiracy
Biopiracy = use of bio-resources by multinational companies and other organisations without proper authorisation from countries and people who have traditionally used them, without compensating the source countries.
- Industrialised nations often hold the patents and profits; developing nations bear the resource cost.
- Traditional knowledge and land races collectively developed over generations get patented by outsiders.
Famous cases:
- Turmeric patent in the US (revoked after CSIR opposed).
- Basmati rice patent (partially revoked).
- Neem patent in Europe (revoked).
India passed the Indian Patents Bill (Second Amendment) to address biopiracy and TRIPS obligations while protecting local knowledge and biodiversity. It also has the Biological Diversity Act (2002) and access-benefit sharing rules.
Key take-aways
- Bt cotton protects itself against bollworms because Cry protoxin activates only in the alkaline insect gut — a beautiful case of selective toxicity.
- RNAi is a natural cellular immune system against foreign RNA — biotechnologists exploit it for pest resistance (e.g. tobacco vs Meloidogyne).
- Recombinant insulin (humulin) ended the shortage and allergy problems of animal-derived insulin. Two chains synthesised in E. coli then joined.
- Gene therapy in ADA-SCID was the first proof-of-concept; bone-marrow-based therapy is the aspirational permanent cure.
- Molecular diagnostics (PCR + ELISA) detect diseases before symptoms.
- Transgenic animals contribute to research, therapeutics (Rosie, α-1 antitrypsin sheep), and vaccine testing.
- GEAC oversight and biopiracy laws protect people, biodiversity, and traditional knowledge from misuse.