Biotechnology and Its Applications - Class 12 Biology

Class 12 Biology | Unit VI

Chapter 12: Biotechnology and Its Applications

Agriculture • Medicine • Transgenic Animals • Ethical Issues

1. Biotechnology in Agriculture

1.1 Bt Cotton — Insect-Resistant Crops

Definition: Bt crops are transgenic plants carrying toxin-producing genes from soil bacterium Bacillus thuringiensis (Bt), giving them resistance to specific insect pests without chemical pesticides.

📋 Discovery: Bacillus thuringiensis was first discovered by Shigetane Ishiwatari (1901). Named after Thuringia, Germany, where re-isolated by Ernst Berliner in 1911.

Mechanism of Action:

Bt toxin exists as inactive protoxin crystals (cry proteins) inside the bacterium.
When insect ingests Bt plant tissue, the alkaline midgut pH dissolves the crystals.
Gut proteases cleave protoxin → active toxin.
Active toxin binds midgut epithelial cell receptors → pore formation.
Pores cause cell swelling and lysis → insect death.

Bt Toxin Gene	Crop	Target Pest
cry IAc	Cotton	Cotton Bollworm
cry IIAb	Cotton	Cotton Bollworm
cry IAb	Corn (Maize)	Corn Borer

⚠️ NEET Focus (2017, 2019, 2022): Bt toxin is NOT harmful to humans — human gut pH is acidic (~1.5–2), protoxin cannot be solubilized, and human midgut cells lack specific receptors. Toxin is insect-group specific.

1.2 Pest-Resistant Plants — RNA Interference (RNAi)

Definition: RNA Interference (RNAi) is a cellular defence mechanism in eukaryotes where double-stranded RNA (dsRNA) silences a specific complementary mRNA. Discovered by Andrew Fire & Craig Mello (Nobel Prize 2006).

Example — Nematode-Resistant Tobacco: Nematode Meloidogyne incognita infests tobacco roots. Scientists introduced a DNA construct (via Agrobacterium) that produces both sense and anti-sense RNA for a nematode-specific gene. These form dsRNA → RISC complex degrades nematode mRNA → nematode cannot survive → plant protected.

⚠️ NEET Focus (2016): DNA introduced in both sense and anti-sense orientation. Vector = Agrobacterium tumefaciens. dsRNA silences mRNA by complementary base pairing.

1.3 Golden Rice — Biofortification

Definition: Golden Rice is a GM variety of rice (Oryza sativa) that produces β-carotene (provitamin A) in its endosperm, addressing Vitamin A deficiency in developing nations.

Developed by Ingo Potrykus & Peter Beyer (1999). Two genes inserted:

psy (phytoene synthase) — from daffodil (Narcissus pseudonarcissus)
crtI (carotene desaturase) — from Erwinia uredovora

⚠️ NEET Focus: β-carotene is produced in the endosperm. Normal rice lacks β-carotene in endosperm. Golden Rice 2 has ~23x more β-carotene than original.

2. Biotechnology in Medicine

2.1 Recombinant Insulin (Humulin)

Definition: Recombinant insulin (Humulin) is human insulin produced by genetically engineered E. coli using rDNA technology — the first licensed recombinant drug (1983, Eli Lilly).

📋 Structure: Chain A = 21 amino acids | Chain B = 30 amino acids | Connected by disulphide bonds. Proinsulin has a C-peptide (removed during maturation; no hormonal activity).

Production Steps:

Genes for Chain-A and Chain-B chemically synthesised.
Each gene inserted into E. coli plasmid alongside β-galactosidase gene (fusion protein tag).
Two E. coli batches produce Chain-A and Chain-B separately.
Chains extracted, purified from β-gal using cyanogen bromide.
Chains combined in vitro → disulphide bonds form → functional Humulin.

⚠️ NEET Focus (2014, 2018, 2021): First licensed rDNA drug — 1983, Eli Lilly. Produced in E. coli. Chain-A & B synthesised separately, then combined. C-peptide has NO hormonal activity.

2.2 Gene Therapy

Definition: Gene therapy = methods to correct a gene defect by delivering a functional copy of the defective gene into target cells using a suitable vector. First tried in 1990.

Types:
• Somatic: Body cells; changes NOT heritable.
• Germline: Germ cells; changes ARE heritable. Ethically controversial.
• Ex vivo: Cells taken out → modified in lab → returned to patient.
• In vivo: Gene delivered directly into patient using viral vectors.

Classic Example: ADA Deficiency — SCID

ADA (Adenosine Deaminase) deficiency → SCID (Severe Combined Immunodeficiency). ADA gene on chromosome 20.
Gene Therapy Steps: Withdraw lymphocytes → introduce functional ADA cDNA via retroviral vector → cultured → infuse back into patient.
Limitation: Lymphocytes are not immortal → periodic infusions needed. Permanent cure = gene into bone marrow stem cells.

⚠️ NEET Focus (2013, 2015, 2019, 2020): ADA-SCID was the first disease treated by gene therapy (1990, W.F. Anderson). Vector = retroviral. ADA gene on chromosome 20.

2.3 Molecular Diagnosis

Definition: Detecting presence of a pathogen or genetic mutation at the molecular (DNA/RNA/protein) level, enabling early, accurate diagnosis.

A. PCR (Polymerase Chain Reaction) — invented by Kary Mullis (Nobel 1993). Uses Taq polymerase (from Thermus aquaticus). Three steps per cycle:

Denaturation (94°C): dsDNA separates into ssDNA.
Annealing (~55°C): Primers hybridise to complementary sequences.
Extension (72°C): Taq polymerase synthesises new strand. Amplification = 2ⁿ copies after n cycles.

B. ELISA (Enzyme Linked Immunosorbent Assay) — based on antigen–antibody interaction with enzyme-linked colour change. Used for HIV, Hepatitis B, pregnancy.

C. DNA Probe (Autoradiography) — single-stranded DNA/RNA tagged with radioactive molecule hybridises to complementary target sequence; detected by autoradiography.

⚠️ NEET Focus (2012, 2016, 2018, 2022): PCR detects HIV before antibodies appear (window period). ELISA = antigen-antibody. DNA probe = radioactive label + autoradiography.

2.4 Recombinant Therapeutics

Therapeutic	Used For	Produced By
Humulin (Insulin)	Diabetes mellitus	E. coli
r-Growth Hormone	Pituitary dwarfism	E. coli
Alpha-1-antitrypsin	Emphysema	Transgenic sheep (Tracy)
Interferon	Viral infections, Cancer	E. coli
Erythropoietin	Anaemia (kidney failure)	CHO cells
Streptokinase	Blood clots (MI)	Streptococcus

30+ rDNA therapeutics approved worldwide; 12 in India

3. Transgenic Animals

Definition: Animals whose DNA has been experimentally manipulated to contain and express a foreign gene from another species in all somatic and germ cells.

📋 Key Facts: Over 95% of transgenic animals are mice. First transgenic mouse: 1974 by Rudolf Jaenisch.

Uses of Transgenic Animals:

Normal Physiology & Development: Understanding gene function and regulation (e.g., overexpression of growth hormone in mice).
Disease Models: Transgenic mice for Cancer, Alzheimer's, Cystic fibrosis, Parkinson's, Rheumatoid arthritis.
Biological Products (Pharming):
- Cow “Rosie” (1997) → human alpha-lactalbumin at 2.4 g/L of milk.
- Sheep “Tracy” → alpha-1-antitrypsin (treats emphysema).
Vaccine Safety Testing: Polio vaccine tested in transgenic mice before human trials.
Chemical Safety / Toxicology: More sensitive; fewer animals needed; faster results.

⚠️ NEET Focus (2015, 2017, 2019): Rosie (cow) = human alpha-lactalbumin (2.4 g/L). Tracy (sheep) = alpha-1-antitrypsin. 95% transgenic animals = mice. Don't confuse these!

4. Ethical Issues in Biotechnology

Biopiracy: Unethical use of biological resources and traditional knowledge by MNCs without compensation.
- Basmati rice — RiceTec Inc. (USA); revoked 2002.
- Turmeric — wound healing patent; revoked by showing prior art.
- Neem — W.R. Grace biopesticide; EPO revoked 2000.
GMO Safety: Long-term impact on health, biodiversity, ecosystems.
Patenting Life Forms: Should genes/organisms be patented?
Germline Gene Therapy: Heritable modifications — consent of future generations.

Indian Regulatory Bodies:
• GEAC (Genetic Engineering Approval Committee) — MoEFCC — approves GMO safety for public release.
• RCGM (Review Committee on Genetic Manipulation) — DBT — regulates ongoing GM research.
• Biological Diversity Act, 2002 — protects India's bio-resources and traditional knowledge.

⚠️ NEET Focus (2013, 2017, 2021): Biopiracy = exploitation by MNCs without authorisation. GEAC approves GM organisms for public use. Indian biopiracy = BTN: Basmati, Turmeric, Neem.

🎓 Key NEET Questions (Previous Years)

Q1. [NEET 2022] Bt toxin protein produced by B. thuringiensis does not kill the bacteria because:

(a) The bacteria are resistant (b) Toxin exists as inactive protoxin (c) Protein is excreted immediately (d) Produced only in spore coat

Answer: (b) The Bt toxin exists as an inactive protoxin crystals in the bacterium. It is only activated by the alkaline pH and proteases of the insect midgut.

Q2. [NEET 2019] First clinical gene therapy was given for treatment of:

(a) Rheumatoid arthritis (b) ADA deficiency (c) Diabetes mellitus (d) Cancer

Answer: (b) First gene therapy (1990, W.F. Anderson) for ADA deficiency (SCID). ADA cDNA introduced into lymphocytes via retroviral vector.

Q3. [NEET 2021] GEAC stands for:

(a) Gene Engineering Approval Committee (b) Genetic Engineering Advisory Committee (c) Genetic Engineering Approval Committee (d) Genome Editing Approval Council

Answer: (c) Genetic Engineering Approval Committee — under Ministry of Environment, Forest and Climate Change. Approves safety of GMOs for public use in India.

Q4. [NEET 2017] Which is a correct match?

(a) Rosie — alpha-1-antitrypsin (b) Tracy — alpha-lactalbumin (c) Rosie — human alpha-lactalbumin (d) Tracy — human β-casein

Answer: (c) Transgenic cow Rosie produces human alpha-lactalbumin at 2.4 g/L. Transgenic sheep Tracy produces alpha-1-antitrypsin.

Q5. [NEET 2014] Drug Humulin used by diabetics was produced by:

(a) Hybridoma technology (b) Recombinant DNA technology (c) Gene amplification (d) Mutation

Answer: (b) Humulin (recombinant human insulin) produced by Eli Lilly using rDNA technology in E. coli (1983). First licensed rDNA drug.

💡 Rapid Revision — Key Numbers

Humulin licensed: 1983 | Company: Eli Lilly
Insulin: Chain A = 21 aa | Chain B = 30 aa
Rosie (cow): 2.4 g/L human alpha-lactalbumin in milk
Transgenic animals: 95% are mice | First: 1974 (Rudolf Jaenisch)
rDNA therapeutics: 30+ worldwide | 12 in India
Golden Rice: β-carotene in endosperm | genes from daffodil + Erwinia
First gene therapy: 1990 | W.F. Anderson | ADA-SCID
RNAi Nobel Prize: 2006 | Andrew Fire & Craig Mello

NCERT Solutions - Biotechnology Applications - Class 12

CLASS 12 BIOLOGY | NCERT SOLUTIONS

Chapter 12 — Biotechnology and Its Applications

All NCERT Exercise Questions with Detailed Solutions | CBSE Marking Scheme

📋 Note: All questions below are directly from NCERT Class 12 Biology Textbook — Chapter 12 Exercise. Answers as per NCERT and CBSE marking scheme.

NCERT Exercise Questions & Solutions

1 Mark Q1. Crystals of Bt toxin produced by some bacteria do not kill the bacteria themselves because:
(a) bacteria are resistant to toxin (b) toxin is immature and inactive (c) bacteria lack receptors for toxin (d) toxin is only active in alkaline pH

✓ Answer: (b)
In Bacillus thuringiensis, the Bt toxin exists as an inactive protoxin enclosed in protein crystals. It only becomes biologically active when it enters the alkaline midgut pH of an insect, where proteases cleave it into the active form. The active toxin then binds epithelial receptors, creating pores → cell lysis → insect death. The bacterium itself has no such alkaline midgut environment.

2 Marks Q2. What are transgenic bacteria? Illustrate using any one example.

✓ Answer
Transgenic bacteria are bacteria whose genome has been altered by introducing a foreign gene from another organism using rDNA technology, enabling them to produce a new protein of commercial or therapeutic value.

Example — Production of Humulin by E. coli:
The genes for insulin Chain-A and Chain-B were chemically synthesised and inserted into E. coli plasmids (along with β-galactosidase gene as fusion tag). Two separate batches of transgenic E. coli produce Chain-A and Chain-B. Chains are then extracted, purified, and combined in vitro to form functional human insulin — Humulin (Eli Lilly, 1983). This was the first licensed rDNA drug.

3 Marks Q3. Compare and contrast the advantages and disadvantages of production of genetically modified crops.

✓ Answer

Advantages	Disadvantages
Increased yield and productivity	May harm non-target organisms
Reduced chemical pesticide use (Bt crops)	Potential gene flow → superweeds
Tolerance to abiotic stresses	Reduced biodiversity (monoculture)
Enhanced nutrition (Golden Rice)	Ethical concerns / biopiracy
Post-harvest loss reduction	Unknown long-term health effects
Resistance to diseases and pests	Terminator seeds — farmers cannot save seeds

3 Marks Q4. What are Cry proteins? Name an organism that produces it. How has man exploited this protein to his advantage?

✓ Answer
Cry Proteins (Crystal proteins) are insecticidal proteins produced by Bacillus thuringiensis and encoded by cry genes. They are stored as inactive protoxin crystals within bacterial spores.

How man exploits Cry proteins:

Biopesticide sprays: Cry toxin spores sprayed as eco-friendly alternative to chemical pesticides.
Bt Transgenic Crops: cry gene inserted into crops:
- cryIAc / cryIIAb → Bt cotton (resists cotton bollworm)
- cryIAb → Bt corn (resists corn borer)
Result: Lower pesticide costs, less pollution, protection of non-target organisms.

5 Marks Q5. What is gene therapy? Illustrate using the example of adenosine deaminase (ADA) deficiency.

✓ Answer
Gene therapy is a collection of methods to correct a genetic defect by delivering a functional copy of the defective gene into the cells of an individual using a suitable vector.

Illustration — ADA Deficiency & Gene Therapy:

Disease: ADA (Adenosine Deaminase) deficiency → SCID (both T and B lymphocytes non-functional).
Cause: Deletion of ADA gene on chromosome 20.
Gene Therapy Steps (Ex-vivo):
- Withdraw lymphocytes from patient's blood.
- Introduce functional ADA cDNA into lymphocytes via retroviral vector.
- Multiply engineered lymphocytes in culture.
- Infuse back into patient → produce ADA enzyme → immune function restored.
Limitation: Lymphocytes are not immortal → periodic re-infusion needed.
Permanent cure: Introduce ADA gene into bone marrow stem cells at early embryonic stage.

5 Marks Q6. Diagrammatically represent the experimental steps in cloning and expressing a human beta-globin gene in E. coli.

✓ Answer
Steps in cloning and expressing a gene in E. coli:

mRNA Isolation: Isolate mRNA from reticulocytes (cells that express β-globin gene).
cDNA Synthesis: Use reverse transcriptase to convert mRNA → cDNA (avoids introns).
Vector Insertion: Cut cDNA and expression vector (e.g., pBR322) with same restriction enzyme → ligate with DNA ligase. Include promoter for E. coli expression.
Transformation: Introduce recombinant plasmid into competent E. coli (heat shock / electroporation).
Selection: Select transformed colonies via antibiotic resistance or blue-white screening.
Expression: E. coli transcribes and translates inserted gene → β-globin protein produced.
Purification: Isolate and purify the expressed protein.
[Diagram: gene → restriction cut → ligation into plasmid → transformation → selection → culture → protein]

3 Marks Q7. Can you suggest a method to remove oil (hydrocarbon) from seeds based on your understanding of RNAi?

✓ Answer
Using the principle of RNAi, oil content in seeds can be reduced by silencing oil biosynthesis genes:

Identify target gene: The gene encoding key fatty acid synthesis enzyme (e.g., fatty acid desaturase).
Construct RNAi vector: Insert the target gene in both sense and anti-sense orientation in a plant expression vector.
Transform plant: Introduce via Agrobacterium or biolistics.
Silencing: In transformed seeds, both sense and anti-sense RNA are produced → form dsRNA → RISC complex activated → target mRNA degraded.
Result: Oil-synthesis enzyme not produced → significantly reduced oil/hydrocarbon content in seeds.

3 Marks Q8. What are transgenic animals? Mention important applications of transgenic animals.

✓ Answer
Transgenic animals: Animals whose DNA has been experimentally altered to contain and express a foreign gene in all their somatic and germ cells.

Applications:

Normal Physiology & Development: Studying role of specific genes in body development.
Disease Models: Mice for Cancer, Alzheimer's, Cystic fibrosis, Parkinson's — study pathology and test drugs.
Biological Products (Pharming): Rosie (cow) → human alpha-lactalbumin (2.4 g/L); Tracy (sheep) → alpha-1-antitrypsin.
Vaccine Safety Testing: Polio vaccine tested in transgenic mice before human use.
Toxicology Testing: More sensitive animals; fewer animals needed; faster results.

5 Marks Q9. Explain the concept of biopiracy. Why should governments develop laws to prevent biopiracy?

✓ Answer
Biopiracy: Unethical use and patenting of biological resources and traditional knowledge of indigenous communities by MNCs without proper authorisation, acknowledgement, or compensation.

Indian Examples:

Basmati rice: RiceTec Inc. (USA) — most claims revoked 2002.
Turmeric: Wound-healing patent — revoked by showing Sanskrit prior art.
Neem: W.R. Grace biopesticide — EPO revoked 2000.

Why Anti-Biopiracy Laws are Necessary:

Protect sovereign rights of nations over bio-resources (CBD, 1992).
Ensure fair benefit-sharing with indigenous communities.
Prevent monopolisation by developed-nation corporations.
Maintain economic justice and recognise IPR of traditional knowledge holders.
India: Biological Diversity Act, 2002 + Patents Amendment Act, 2005.

3 Marks Q10. Briefly explain the PCR technique. Why is it called the polymerase chain reaction?

✓ Answer
PCR (Polymerase Chain Reaction) is a technique for amplifying specific DNA sequences in vitro exponentially. Developed by Kary Mullis (Nobel Chemistry, 1993).

Steps (repeated 30–35 cycles):

Denaturation (94°C): dsDNA separates into two ssDNA strands.
Annealing (~55°C): Specific primers hybridise to complementary sequences on each strand.
Extension (72°C): Taq DNA polymerase extends primer → new complementary strand synthesised.

Each cycle doubles the DNA → 2ⁿ copies after n cycles (exponential amplification).

Why "Polymerase Chain Reaction"? Because it uses DNA polymerase (Taq polymerase) repetitively in a chain of thermal cycles, each cycle producing products used as templates for the next — creating an exponential chain-like amplification.

Facts Capsule - Biotechnology Applications - Class 12

CLASS 12 BIOLOGY | NEET RAPID CAPSULE

Facts & High-Yield Points

Chapter 12 — Biotechnology and Its Applications | 25 Key Facts for NEET

🌿 Agriculture & GM Crops

FACT #01 — Bt Cotton Genes

cry IAc / cry IIAb → cotton bollworm. cry IAb → corn borer. Species-specific. Do NOT affect mammals.

FACT #02 — Bt Toxin Activation

Exists as inactive protoxin crystals in bacteria. Active only in alkaline insect midgut via proteases. Human gut pH (~1.5–2) = safe.

FACT #03 — RNAi Example

Nematode Meloidogyne incognita infects tobacco roots. RNAi via Agrobacterium vector introduces dsRNA (sense + anti-sense) → nematode gene silenced.

FACT #04 — RNAi Nobel

Discovered by Andrew Fire & Craig Mello. Nobel Prize in Physiology/Medicine — 2006. dsRNA initiates gene silencing via RISC complex.

FACT #05 — Golden Rice

β-carotene in endosperm. Developed: Potrykus & Beyer, 1999. Genes: psy (daffodil) + crtI (Erwinia uredovora). Golden Rice 2: ~23x more β-carotene.

FACT #06 — Bt History

First described by Shigetane Ishiwatari (1901). Named after Thuringia, Germany by Ernst Berliner (1911). Used as biopesticide since 1960s.

💊 Medicine & Therapeutics

FACT #07 — Humulin

First licensed rDNA drug (1983). Made by Eli Lilly in E. coli. Chain A = 21 aa; Chain B = 30 aa. Produced separately, combined in vitro.

FACT #08 — Insulin Structure

Proinsulin = A + C + B. C-peptide removed during maturation (NO hormonal activity). A-B joined by disulphide bonds.

FACT #09 — Gene Therapy / ADA-SCID

First gene therapy: 1990, W.F. Anderson. ADA gene on chromosome 20. Vector = retroviral. Lymphocytes not immortal → periodic infusions needed.

FACT #10 — ADA Deficiency

ADA = Adenosine Deaminase. Deficiency → SCID. Both T & B lymphocytes affected. Treatment: enzyme replacement, bone marrow transplant, or gene therapy.

FACT #11 — PCR

Invented by Kary Mullis (Nobel 1993). Enzyme: Taq polymerase (Thermus aquaticus). Steps: 94°C (denature) → 55°C (anneal) → 72°C (extend). Copies = 2ⁿ.

FACT #12 — ELISA vs DNA Probe

ELISA: antigen-antibody + enzyme colour change. DNA Probe: radioactive label + autoradiography. ELISA = No radiation; DNA probe = Yes radiation.

FACT #13 — Recombinant Drugs

Worldwide: 30+ approved. In India: 12 marketed. Examples: Alpha-1-antitrypsin (emphysema), Interferon (viral), Erythropoietin (anaemia — CHO cells).

FACT #14 — HIV Early Detection

PCR (RT-PCR) can detect HIV during window period (before antibodies appear). ELISA detects HIV antibodies (later stage). PCR = more sensitive, earlier.

🐅 Transgenic Animals

FACT #15 — Rosie vs Tracy

Rosie (cow) → human alpha-lactalbumin (2.4 g/L) — nutritional.
Tracy (sheep) → alpha-1-antitrypsin — therapeutic (emphysema).

FACT #16 — Transgenic Stats

95%+ of transgenic animals = mice. First: 1974, Rudolf Jaenisch. Foreign gene present in ALL cells (somatic + germ).

FACT #17 — Disease Models

Transgenic mice for: Cancer, Alzheimer's, Cystic fibrosis, Parkinson's, Rheumatoid arthritis. Allow drug testing before human trials.

FACT #18 — Pharming

Transgenic animals used as protein factories (pharming). Useful for complex proteins needing post-translational modifications (unlike E. coli). Economic advantage for large-scale.

⚖️ Ethics & Biopiracy

FACT #19 — Biopiracy

Unethical use of bio-resources + traditional knowledge by MNCs without authorisation or compensation. Violates national sovereignty over bio-resources.

FACT #20 — Indian Cases (BTN)

Basmati (RiceTec, revoked 2002) | Turmeric (wound healing, revoked) | Neem (W.R. Grace, EPO revoked 2000). All three — India successfully challenged.

FACT #21 — GEAC

Genetic Engineering Approval Committee. Under: MoEFCC. Function: Approves GM research validity and GMO safety for public release in India.

FACT #22 — Indian Laws

Biological Diversity Act, 2002 + Patents Amendment Act, 2005. CBD (Convention on Biological Diversity, 1992) — sovereign rights over bio-resources.

🏭 Industry & Environment

FACT #23 — First Living Patent

First patent on a living organism: 1980, Ananda Mohan Chakravarti (India-born). Organism: oil-degrading Pseudomonas putida (“superbug”). US Supreme Court case.

FACT #24 — Bioremediation

Pseudomonas putida degrades crude oil/hydrocarbons. Transgenic bacteria engineered for specific pollutant degradation. Eco-friendly cleanup technology.

FACT #25 — Industrial Enzymes

Recombinant enzymes: Lipase (detergent), Amylase (food), Pectinase (juice), Streptokinase (clot buster from Streptococcus).

🧠 Mnemonics — Remember Fast

Bt Genes: “Cats And Collie” Cry IAc + cry IIAb → Cotton bollworm | cry IAb → Corn borer

Insulin Chains: “A is Shorter” Chain A = 21 aa (shorter) | Chain B = 30 aa | C-peptide = removed

Rosie vs Tracy: “Cow Gives Milk; Sheep Gives Medicine” Rosie (cow) = alpha-lactalbumin (nutrition) | Tracy (sheep) = alpha-1-antitrypsin (therapy)

Biopiracy: “BTN” Basmati | Turmeric | Neem — All three Indian biopiracy cases won.

📊 NEET Comparison: PCR vs ELISA vs DNA Probe

Feature	PCR	ELISA	DNA Probe
Detects	DNA / RNA sequences	Antigens / Antibodies	Specific DNA sequences
Principle	DNA amplification	Antigen-antibody + enzyme	Hybridisation
Label	None (gel electrophoresis)	Enzyme (colorimetric)	Radioactive molecule
Detection	Gel bands	Colour change	Autoradiography
HIV use	RT-PCR (very early)	Antibody (later)	Rarely used

🔢 Critical Numbers — Never Forget

1983 — Humulin licensed (Eli Lilly) 21 aa — Insulin Chain A 30 aa — Insulin Chain B 2.4 g/L — Rosie's alpha-lactalbumin 95% — Transgenic = mice 30+ — rDNA drugs worldwide 12 — rDNA drugs in India 1990 — First gene therapy 2006 — RNAi Nobel Prize 1974 — First transgenic mouse 1999 — Golden Rice developed 1980 — First patent on living organism

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