Biotechnology and its Applications
NCERT Line-by-Line Breakdown for NEET 2026
Unit 4: BiotechnologyBiotechnology has provided humans with useful products by using microbes, plants, animals, and their metabolic machinery. The three critical research areas are: (1) Providing the best catalyst (microbe/enzyme), (2) Creating optimal conditions for the catalyst to act, and (3) Downstream processing technologies.
1. Biotechnological Applications in Agriculture
Genetically Modified Organisms (GMOs): Plants, bacteria, fungi, and animals whose genes have been altered by manipulation.
- Made crops more tolerant to abiotic stresses (cold, drought, salt, heat).
- Reduced reliance on chemical pesticides (pest-resistant crops).
- Enhanced nutritional value (e.g., Golden Rice enriched with Vitamin A).
A. Bt Cotton (Pest Resistant)
Bacillus thuringiensis produces proteins that kill certain insects (Lepidopterans – tobacco budworm/armyworm; Coleopterans – beetles; Dipterans – flies/mosquitoes).
The Bt toxin protein exists as inactive Protoxins. When an insect ingests it, the Alkaline pH of the gut solubilizes the crystals → Toxin activates → Binds to midgut epithelial cells → Creates pores → Cell swelling and lysis → Death of insect.
The Gene (cry):
• cryIAc and cryIIAb control Cotton Bollworms.
• cryIAb controls Corn Borer.
B. RNA Interference (RNAi) – Pest Resistant Tobacco
Nematode Meloidogyne incognita infects roots of tobacco plants. Prevented using RNAi (Gene Silencing).
- Principle: Silencing of specific mRNA due to complementary dsRNA molecule.
- Vector: Agrobacterium vectors used to introduce nematode-specific genes into host.
- Mechanism: Produces both sense and anti-sense RNA → form dsRNA → Initiates RNAi → Nematode cannot survive (mRNA silenced).
2. Biotechnological Applications in Medicine
Recombinant therapeutics allow mass production of safe and effective drugs (no immunological responses like animal insulin).
A. Genetically Engineered Insulin
Early sources: Pancreas of slaughtered cattle/pigs (caused allergies).
Mammals secrete Pro-insulin (contains extra C-peptide). C-peptide is removed during maturation.
Eli Lilly (1983): An American company prepared two DNA sequences corresponding to A and B chains of human insulin → Introduced into E. coli plasmids → Produced chains separately → Extracted and combined by creating disulphide bonds.
B. Gene Therapy
Correction of a genetic defect. First clinical gene therapy (1990) given to a 4-year-old girl with ADA (Adenosine Deaminase) deficiency.
- Cause: Deletion of gene for adenosine deaminase (crucial for immune system).
- Treatment: Lymphocytes from patient blood grown in culture → Functional ADA cDNA introduced (using Retroviral vector) → Returned to patient. (Periodic infusion required as cells are not immortal).
- Permanent Cure: If gene from marrow cells is introduced at early embryonic stages.
C. Molecular Diagnosis
Early diagnosis is not possible with conventional methods (Serum/Urine analysis).
PCR: Detects very low concentration of bacteria/virus by amplification (e.g., HIV in suspected AIDS patients, Cancer mutations).
ELISA: Based on Antigen-Antibody interaction.
3. Transgenic Animals
Animals with manipulated DNA to possess and express an extra (foreign) gene. (95% are mice).
| Purpose | Description/Example |
|---|---|
| Normal Physiology | Study how genes are regulated and affect body functions (e.g., Growth factors). |
| Study of Disease | Models for human diseases (Cancer, Cystic fibrosis, Rheumatoid arthritis, Alzheimer’s). |
| Biological Products | Production of Alpha-1-antitrypsin (Emphysema). Rosie (First Transgenic Cow, 1997): Produced human protein-enriched milk (2.4 g/L) containing Alpha-lactalbumin. |
| Vaccine Safety | Transgenic mice used to test Polio vaccine safety before monkeys/humans. |
| Chemical Safety | Toxicity testing. Animals made more sensitive to toxic substances for faster results. |
4. Ethical Issues
GEAC (Genetic Engineering Approval Committee)
Indian Government organization. Decisions regarding:
1. Validity of GM research.
2. Safety of introducing GM organisms for public services.
Biopiracy
Use of bio-resources by multinational companies without proper authorization/compensation.
- Basmati Rice: In 1997, an American company got patent rights through the US Patent and Trademark Office. They crossed Indian Basmati with semi-dwarf varieties to claim a “new” variety.
- Turmeric & Neem: Attempts were also made to patent their traditional uses.
📝 Rapid Fire MCQs
Q1. The first clinical gene therapy was given for treating:
- A) Diabetes mellitus
- B) Chicken pox
- C) Rheumatoid arthritis
- D) Adenosine deaminase deficiency
Click to check Answer
Answer: D) Adenosine deaminase deficiency (SCID).
Q2. Which gene was used to produce insect-resistant cotton plants?
- A) cryIAc
- B) trp gene
- C) lacZ gene
- D) ampR gene
Click to check Answer
Answer: A) cryIAc (and cryIIAb).