Home/Biology/Chapter 10 — Biotechnology and Its Applications
Class 12 Biology

Biotechnology and Its Applications

Tissue culture, GM crops, Bt cotton, RNA interference, genetically engineered insulin, gene therapy, molecular diagnosis, transgenic animals and ethical issues — with SVG diagrams, MCQs, A-R and PYQs.

4NCERT Sections
12MCQs
6Assertion–Reason
5PYQs
Section 01

Biotechnological Applications in Agriculture

10.0Scope of Biotechnology

Biotechnology deals with industrial-scale production of biopharmaceuticals and biologicals using genetically modified microbes, fungi, plants and animals — therapeutics, diagnostics, GM crops, processed food, bioremediation, waste treatment and energy. Three critical research areas: (i) the best catalyst (improved microbe or pure enzyme); (ii) optimal conditions through engineering; (iii) downstream processing.

Three options to raise food production: agro-chemical based, organic, and genetically engineered crop-based agriculture. The Green Revolution tripled food supply but was not enough; agrochemicals are costly for developing-world farmers and conventional breeding hit limits.

10.1.1Tissue Culture, Micropropagation and Somatic Hybridisation

  • In the 1950s it was learnt that whole plants can be regenerated from explants (any plant part grown in a test tube under sterile conditions in special nutrient medium). This capacity is totipotency.
  • Medium: carbon source (sucrose), inorganic salts, vitamins, amino acids and growth regulators like auxins and cytokinins.
  • Micropropagation = producing thousands of plants in a short time. All are genetically identical — somaclones. Commercially done in tomato, banana, apple.
  • Virus-free plants: even in an infected plant, the meristem (apical and axillary) is free of virus; culturing it in vitro gives healthy plants (banana, sugarcane, potato).
  • Somatic hybridisation: cell walls are digested to get naked protoplasts; protoplasts of two varieties/species are fused to give hybrid protoplasts → somatic hybrids. Tomato + potato = pomato (did not have all desired commercial characteristics).
V1 · Tissue culture and micropropagation ① Explant ② Sterile nutrient medium ③ Whole plant ④ Micropropagation any plant part (e.g. meristem tip) sucrose, salts, vitamins, amino acids, auxins + cytokinins regenerated in vitro = TOTIPOTENCY thousands of plants genetically identical = SOMACLONES Meristem culture → virus-free plants (banana, sugarcane, potato)
V2 · Somatic hybridisation — the 'pomato' Tomato cell Potato cell Naked protoplast Naked protoplast digest cell wall Hybrid protoplast (fusion) Somatic hybrid = POMATO grown into new plant
Section 01 (contd.)

Genetically Modified Crops

10.1.2GMO and Its Uses

GMO

Plants, bacteria, fungi and animals whose genes have been altered by manipulation.

Genetic modification has: (i) made crops tolerant to abiotic stresses (cold, drought, salt, heat); (ii) reduced reliance on chemical pesticides (pest-resistant crops); (iii) reduced post-harvest losses; (iv) increased efficiency of mineral usage (preventing early exhaustion of soil fertility); (v) enhanced nutritional value, e.g. golden rice (Vitamin A enriched). GM also creates plants supplying starches, fuels and pharmaceuticals to industry.

Section 01 (contd.)

Bt Toxin and RNA Interference

10.1.3Bt Cotton

  • Bacillus thuringiensis strains make proteins killing lepidopterans (tobacco budworm, armyworm), coleopterans (beetles) and dipterans (flies, mosquitoes). The bacterium forms protein crystals with the insecticidal protein.
  • The toxin exists as inactive protoxin — so it does not kill the bacterium. In the insect gut, alkaline pH solubilises the crystals and activates it; the active toxin binds to midgut epithelial cells, creates pores → cell swelling and lysis → death.
  • The toxin gene is named cry: cryIAc and cryIIAb control cotton bollworms; cryIAb controls corn borer. Genes are chosen by crop and target pest (Bt toxins are insect-group specific). Examples: Bt cotton, Bt corn, rice, tomato, potato, soyabean — a bio-pesticide.
V3 · How Bt toxin kills an insect larva Bt bacterium Insect eats plant Alkaline gut pH Active toxin binds Cells swell, lyse forms protein crystals = inactive PROTOXIN (safe for bacterium) ingests protoxin (or Bt plant tissue with cry gene product) solubilises crystals → ACTIVE toxin midgut epithelial cells; toxin forms PORES pores → swelling and lysis → insect DIES cry genes from Bt put into cotton → Bt cotton protects itself against bollworm

10.1.4Pest-Resistant Plants by RNA Interference

  • The nematode Meloidogyne incognitia infects tobacco roots and reduces yield.
  • RNAi occurs in all eukaryotes as cellular defence: a complementary dsRNA binds a specific mRNA and prevents translation (silencing). The source can be RNA viruses or transposons that replicate via RNA.
  • Using Agrobacterium vectors, nematode-specific genes were introduced into the host plant to make both sense and anti-sense RNA. These form dsRNA, silencing the nematode's specific mRNA, so the parasite cannot survive in the transgenic host.
V4 · RNAi protects tobacco from nematode ① Agrobacterium ② Host makes RNA ③ dsRNA forms ④ Silences mRNA ⑤ Protected plant delivers nematode- specific gene into tobacco cells SENSE and ANTI-SENSE RNA of the nematode: translation blocked nematode cannot survive in the transgenic root complementary sense + anti-sense strands = double-stranded RNA RNA interference — cellular defence in all eukaryotes, used here to silence a parasite
Section 02

Biotechnological Applications in Medicine

10.2Recombinant Therapeutics

Recombinant DNA technology enables mass production of safe and effective therapeutic drugs; they do not induce unwanted immune responses (unlike similar products from non-human sources) and are free of infection risk. About 30 recombinant therapeutics approved worldwide; 12 marketed in India.

10.2.1 Genetically Engineered Insulin

  • Earlier insulin was extracted from pancreas of slaughtered cattle and pigs — some patients developed allergy/reactions to the foreign protein. Insulin cannot be taken orally (it is a protein and would be digested).
  • Insulin = two short polypeptide chains, A and B, linked by disulphide bridges. In mammals it is made as pro-insulin with an extra C peptide that is removed during maturation.
  • 1983, Eli Lilly prepared two DNA sequences for chains A and B and introduced them into plasmids of E. coli. The chains were produced separately, extracted and combined by disulphide bonds to form human insulin.
V5 · Pro-insulin processing and rDNA insulin In the human body Chain B C peptide Chain A PRO-INSULIN (pro-hormone) C peptide removed Chain B Chain A disulphide bridges MATURE INSULIN By rDNA technology (Eli Lilly, 1983) DNA for chain A DNA for chain B Two plasmids → E. coli Combine chains prepared as a DNA sequence prepared as a DNA sequence chains A and B made separately, extracted disulphide bonds → human insulin
Section 02 (contd.)

Gene Therapy

10.2.2Gene Therapy — ADA Deficiency

Definition

A collection of methods to correct a gene defect diagnosed in a child/embryo by delivering a normal gene into the individual's cells and tissues, to take over the function of the non-functional gene.

  • First clinical gene therapy: 1990, a 4-year-old girl with adenosine deaminase (ADA) deficiency — ADA is crucial for the immune system; the disorder is caused by deletion of the ADA gene.
  • Other treatments (bone marrow transplantation, enzyme replacement therapy by injection) are not completely curative.
  • Procedure: patient's lymphocytes are grown in culture outside the body → functional ADA cDNA introduced using a retroviral vector → cells returned to patient. Cells are not immortal, so periodic infusions are needed. A permanent cure would need the gene (from marrow cells that produce ADA) introduced into early embryonic cells.
V6 · Gene therapy for ADA deficiency ① Patient lymphocytes ② Cultured outside ③ Normal ADA cDNA ④ Returned to patient ⑤ Not immortal taken from blood of child with ADA deficiency grown in the laboratory introduced using a RETROVIRAL VECTOR genetically engineered lymphocytes make ADA periodic infusions needed; permanent cure = early embryo cells First clinical gene therapy — 1990 (4-year-old girl)

10.2.3Molecular Diagnosis

  • Conventional methods (serum/urine analysis) cannot detect disease early. Recombinant DNA technology, PCR and ELISA allow early diagnosis.
  • PCR amplifies nucleic acid of a pathogen present in very low concentration, before symptoms appear. Used to detect HIV in suspected AIDS patients, mutations in genes in suspected cancer patients, and many genetic disorders.
  • Probe: a single-stranded DNA/RNA tagged with a radioactive molecule hybridises to its complementary DNA in a clone of cells; detected by autoradiography. A clone with a mutated gene will not appear on the film (no complementarity).
  • ELISA — based on antigen–antibody interaction; infection detected by antigens (proteins, glycoproteins) or by antibodies made against the pathogen.
Section 03

Transgenic Animals

10.3Why Make Transgenic Animals?

Animals whose DNA is manipulated to express an extra (foreign) gene. Transgenic rats, rabbits, pigs, sheep, cows and fish exist, but over 95% of all transgenic animals are mice.

V7 · Uses of transgenic animals Transgenic animal >95% mice Normal physiology Study of disease Biological products Vaccine safety Chemical safety testing how genes are regulated; growth factors (e.g. insulin-like GF) models of cancer, cystic fibrosis, rheumatoid arthritis, Alzheimer's α-1-antitrypsin (emphysema); 'Rosie' cow milk, 2.4 g/L protein transgenic mice test polio vaccine → may replace monkeys animals more sensitive to toxins → results in less time (toxicity test)
  • Biological products: human protein α-1-antitrypsin for emphysema; attempts for PKU and cystic fibrosis. In 1997 the first transgenic cow, Rosie, produced human protein-enriched milk (2.4 g/L) containing human α-lactalbumin — nutritionally more balanced for babies.
Section 04

Ethical Issues

10.4Regulation, Patents and Biopiracy

  • Manipulation of living organisms needs ethical standards; GM organisms can have unpredictable results in ecosystems.
  • India set up GEAC (Genetic Engineering Approval Committee) to decide on the validity of GM research and the safety of introducing GMOs for public services.
  • Patents: public anger when companies patent products based on genetic material, plants and resources long used by farmers and indigenous people.
  • Basmati: India has ~200,000 rice varieties, 27 documented Basmati varieties. In 1997 an American company got a US patent on a 'new' Basmati derived from Indian farmers' varieties crossed with semi-dwarf lines. Attempts were also made to patent uses based on turmeric and neem.
Biopiracy

Use of bio-resources by multinational companies and other organisations without proper authorisation from the countries and people concerned and without compensatory payment.

  • Industrialised nations are rich financially but poor in biodiversity and traditional knowledge; developing countries are rich in both. Hence some nations are developing laws against unauthorised exploitation; the Indian Parliament cleared the second amendment of the Indian Patents Bill.
Practice

📝 Solved Examples with Step Marking

📋 2 Marks

Q1. Which part of the plant is best suited for making virus-free plants and why?

Part 1 Mark

The meristem (apical and axillary).

Reason 1 Mark

Even in a virus-infected plant, the meristem is free of virus; cultured in vitro it gives healthy plants.

📋 2 Marks

Q2. Crystals of Bt toxin do not kill the bacterium that produces them. Why?

Inactive form 1 Mark

The toxin exists as an inactive protoxin in the bacterium.

Activation 1 Mark

It is activated only in the alkaline gut of the insect which solubilises the crystals.

📋 3 Marks

Q3. How is human insulin produced using E. coli? Why is it better than animal insulin?

Production 1 Mark

DNA sequences for chains A and B are introduced into plasmids of E. coli, which make the chains separately.

Assembly 1 Mark

Chains are extracted and joined by disulphide bonds to form mature insulin.

Advantage 1 Mark

Identical to human insulin → no allergic/immune reaction, no infection risk, large-scale supply.

Test Yourself

✍️ MCQ Practice

Score: 0 / 12
New Pattern

🎯 Assertion–Reason

(A) Both true, R explains A. (B) Both true, R does NOT explain A. (C) A true, R false. (D) A false, R true.

Score: 0 / 6
Exam Focus

📖 Important Board Questions

NCERT

Q. What is gene therapy? Illustrate with the example of ADA deficiency.

Answer 3 Marks

Gene therapy corrects a gene defect by inserting a normal gene. ADA deficiency (deletion of the adenosine deaminase gene) was first treated in 1990 by culturing the patient's lymphocytes, introducing functional ADA cDNA with a retroviral vector and returning the cells; periodic infusions are needed, while a permanent cure needs early embryonic cells.

NCERT

Q. What are Cry proteins? Name an organism that produces them and explain their use.

Answer 3 Marks

Cry proteins are insecticidal Bt toxins from Bacillus thuringiensis. The cry genes (cryIAc, cryIIAb, cryIAb) were cloned into crops such as cotton (Bt cotton) so plants resist bollworm and corn borer without chemical pesticides.

NCERT

Q. Explain how RNA interference protects tobacco plants from nematode infection.

Answer 3 Marks

Nematode-specific genes introduced via Agrobacterium make sense and anti-sense RNA, which form dsRNA and silence the nematode's specific mRNA; the parasite cannot survive in the transgenic roots.

NCERT

Q. What is biopiracy? Give an example.

Answer 2 Marks

Use of bio-resources by companies without proper authorisation and compensatory payment. Example: the 1997 US patent on Basmati rice based on Indian farmers' varieties (also attempts on turmeric and neem).

NCERT

Q. State any four uses of transgenic animals.

Answer 2 Marks

Study of normal physiology and development; models of human diseases (cancer, cystic fibrosis); production of biological products (α-1-antitrypsin, Rosie's milk); vaccine safety testing; chemical (toxicity) safety testing.