Introduction — NCERT Solutions

Given/Concept: The term 'Biotechnology' combines 'biology' and 'technology'. It refers to the use of living organisms, cells, or their components to develop products and processes for human welfare.

Definition:
Biotechnology is defined as the integration of natural sciences and engineering sciences in order to achieve the application of organisms, cells, parts thereof, and molecular analogues for products and services. (European Federation of Biotechnology, EFB)

In simpler terms, biotechnology involves the use of biological systems (microorganisms, plants, animals, or their components) to develop useful products and processes.

Key aspects of Biotechnology:

1. It uses living organisms or their derivatives.
2. It involves manipulation at the molecular, cellular, or organismal level.
3. It aims at producing useful products or solving problems.

Examples:

Conclusion: Biotechnology is a broad, multidisciplinary field that harnesses biological knowledge and engineering principles to benefit agriculture, medicine, industry, and the environment.

Given/Concept: Biotechnology has been practised by humans for thousands of years, but the nature and scale of its application have changed dramatically with advances in science.

Comparative Account:

Key Distinction:

• Ancient biotechnology relied on naturally occurring biological processes without understanding the underlying mechanisms.
• Modern biotechnology deliberately manipulates genetic material (DNA) to achieve desired outcomes with precision and predictability.

Conclusion: While ancient biotechnology laid the foundation by demonstrating the utility of microorganisms and selective breeding, modern biotechnology has revolutionised the field by enabling precise genetic manipulation, leading to products and solutions that were previously unimaginable.

Given/Concept: Modern biotechnology has wide-ranging applications across medicine, agriculture, and the environment. Each area is elaborated below.

(a) Biopharmaceutical Production

Definition: Biopharmaceuticals are therapeutic products derived from biological sources using biotechnological methods.

Role of Biotechnology:

• Recombinant DNA technology allows the insertion of human genes into microorganisms or other host cells to produce therapeutic proteins.
• Example 1 — Insulin: The human insulin gene was cloned into Escherichia coli. The bacterium acts as a bioreactor and produces human insulin (Humulin), which is used to treat diabetes mellitus. This replaced the earlier practice of extracting insulin from pig/cow pancreas.
• Example 2 — Erythropoietin (EPO): Produced using recombinant technology; used to treat anaemia in patients with chronic kidney disease.
• Example 3 — Vaccines: Recombinant hepatitis B vaccine is produced in yeast. The gene encoding the surface antigen (HBsAg) is expressed in yeast cells.
• Example 4 — Monoclonal Antibodies: Used in targeted cancer therapy (e.g., Herceptin for breast cancer) and diagnostic kits.
• Example 5 — Interferons: Produced by recombinant bacteria; used in antiviral and anticancer therapy.

Significance: Biopharmaceuticals are safer, more specific, and available in large quantities compared to traditionally derived drugs.

(b) Gene Therapy and Applications

Definition: Gene therapy is the technique of inserting a functional gene into a patient's cells to correct a genetic disorder or treat a disease.

Role of Biotechnology:

• Defective or missing genes responsible for genetic diseases are identified using molecular biology tools.
• A correct copy of the gene is delivered into the patient's cells using vectors (usually modified viruses like retroviruses or adenoviruses) or non-viral methods.

Types:

1. Somatic gene therapy: Correction of defective genes in somatic (body) cells. Changes are not heritable.
2. Germline gene therapy: Modification of germ cells (egg/sperm). Changes are heritable (ethically controversial).

Applications:

• ADA deficiency (Adenosine Deaminase deficiency): The first successful gene therapy was performed for this condition. The ADA gene was introduced into the patient's lymphocytes.
• Cystic fibrosis: Gene therapy trials aim to deliver the correct CFTR gene to lung cells.
• Haemophilia: Delivery of clotting factor genes (Factor VIII or IX).
• Cancer therapy: Introduction of tumour suppressor genes or genes that make cancer cells sensitive to drugs.
• Inherited blindness (Leber's congenital amaurosis): Corrected by delivering the RPE65 gene to retinal cells.

Significance: Gene therapy offers the potential for permanent cure of genetic diseases rather than just symptomatic treatment.

(c) Abiotic Stress Resistance in Crops

Definition: Abiotic stresses are non-living environmental factors (drought, salinity, extreme temperature, flooding, heavy metals) that adversely affect crop growth and yield.

Role of Biotechnology:

• Genes responsible for tolerance to abiotic stresses are identified from stress-tolerant organisms and introduced into crop plants.
• Genetic engineering allows precise transfer of stress-tolerance genes that would be difficult or impossible to achieve through conventional breeding.

Examples:

• Drought tolerance: Genes encoding proteins like dehydrins or transcription factors (e.g., DREB — Drought Response Element Binding proteins) are introduced into crops like wheat and rice to improve survival under water deficit.
• Salt tolerance: Overexpression of genes encoding Na⁺/H⁺ antiporters (e.g., AtNHX1 from Arabidopsis) in tomato and rice improves growth in saline soils.
• Cold/frost tolerance: Genes from cold-tolerant organisms encoding antifreeze proteins or cold-shock proteins are introduced into crops.
• Heat tolerance: Genes encoding heat shock proteins (HSPs) help plants survive high temperatures.
• Flood tolerance: The Sub1A gene in rice confers submergence tolerance; flood-tolerant 'Swarna Sub1' rice variety has been developed.

Significance: With climate change intensifying abiotic stresses, biotechnology-derived stress-tolerant crops are crucial for ensuring food security.

(d) Crops with Insect Resistance

Definition: Insect-resistant crops are genetically engineered plants that can defend themselves against insect pests, reducing the need for chemical pesticides.

Role of Biotechnology:

• The most widely used approach involves introducing genes from the soil bacterium ***Bacillus thuringiensis* (Bt)** into crop plants.

Mechanism of Bt Crops:

1. B. thuringiensis produces Cry proteins (crystal proteins / δ-endotoxins) that are toxic to specific insect larvae.
2. The cry genes (e.g., cry1Ac, cry2Ab, cry1Ab) are isolated and introduced into the plant genome.
3. The Cry protein is produced in the plant cells. When an insect larva feeds on the plant, the protein is ingested.
4. In the alkaline gut of the insect, the protein is activated, binds to receptors in the gut epithelium, creates pores, and causes cell lysis → death of the insect.
5. The protein is non-toxic to mammals (requires alkaline pH for activation; mammalian gut is acidic).

Examples:

• Bt cotton (cry1Ac and cry2Ab genes): Resistant to bollworm (Helicoverpa armigera).
• Bt brinjal (cry1Ac gene): Resistant to fruit and shoot borer (Leucinodes orbonalis).
• Bt maize (cry1Ab gene): Resistant to European corn borer.

Other approaches:

• RNAi (RNA interference): Introducing dsRNA specific to essential insect genes silences those genes in the insect, causing its death.
• Protease inhibitor genes: Introduced into plants to inhibit insect digestive enzymes.

Significance: Bt crops reduce chemical pesticide use, lower production costs, decrease environmental pollution, and improve crop yield.

(e) Environmental Protection and Conservation

Role of Biotechnology:
Biotechnology contributes significantly to environmental protection through the following approaches:

1. Bioremediation:

• Use of microorganisms to degrade or detoxify environmental pollutants.
• Genetically engineered bacteria (e.g., Pseudomonas putida — the first patented organism) can degrade multiple hydrocarbons in oil spills.
• Bacteria engineered to degrade heavy metals (mercury, arsenic) from contaminated soil and water.

2. Biopesticides and Biofertilisers:

• Replacing chemical pesticides with microbial biopesticides (e.g., Bt-based sprays) reduces soil and water pollution.
• Biofertilisers (e.g., Rhizobium, Azotobacter) reduce dependence on chemical fertilisers, preventing eutrophication.

3. Biodegradable Plastics:

• Microorganisms like Alcaligenes eutrophus produce polyhydroxybutyrate (PHB), a biodegradable plastic, reducing plastic pollution.

4. Biogas Production:

• Anaerobic microorganisms convert organic waste into biogas (methane), providing clean energy and reducing waste.

5. Conservation of Biodiversity:

• Cryopreservation of germplasm (seeds, embryos, pollen) using biotechnological methods preserves genetic diversity of endangered species.
• Tissue culture and micropropagation allow rapid multiplication of rare and endangered plant species.
• DNA barcoding and molecular markers help in identification and monitoring of species.

6. Phytoremediation:

• Transgenic plants engineered to accumulate heavy metals (hyperaccumulators) can clean up contaminated soils.

7. Biosensors:

• Biotechnology-based biosensors detect environmental pollutants (pesticides, heavy metals, pathogens) quickly and accurately.

Conclusion: Biotechnology offers powerful, eco-friendly tools for environmental monitoring, pollution control, waste management, and biodiversity conservation.