Biotechnology and its Applications Class 12 Notes जैव प्रौद्योगिकी एवं उसके उपयोग — कक्षा 12 जीव विज्ञान अध्याय 10

Revise these first (prerequisites)

• Chapter 9: rDNA technology, vectors, PCR
• Chapter 5: mRNA, translation, protein synthesis
• Chapter 7: immunity, antibodies, AIDS

1. The real benefit of biotechnology

   In Chapter 9 we learnt the tools (enzymes, vectors, PCR). In this chapter we will see the benefits they have brought to agriculture, medicine and disease diagnosis. Tools first, now their uses.

2. GM crops — pest-resistant crops

   Plants whose genes have been altered are called GMO / GM crops. These crops can better tolerate drought, cold or salt, resist insect pests, and need fewer chemical pesticides. Golden rice (rich in vitamin A) is also a GM crop.

3. The story of Bt cotton

   The bacterium Bacillus thuringiensis produces a protein (Bt toxin) that kills certain insects. The gene for this protein was introduced into cotton — now cotton makes its own 'insecticide', and bollworms die after feeding on it.

4. Medicine: insulin

   Diabetes patients need insulin. Earlier it was extracted from animals, which caused allergies in some people. Now human insulin — exactly like the human one — is produced in bacteria (E. coli) using rDNA technology.

5. Gene therapy and early diagnosis

   Inserting a correct gene to treat a disease caused by a defective gene is gene therapy. And techniques like PCR can detect a disease at a very early stage, when the pathogen is present in very low numbers.

6. True-or-false question

   GM organisms and patents also raise some ethical questions. In India, GEAC decides the safety of GM research and the public use of GM organisms. Using a country's traditional biological resources without permission/compensation is called biopiracy.

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As per NCERT 2026-27 — every point you need for the board exam.

1. GMO

   Organisms whose genes have been manipulated. Benefits: tolerance to abiotic stress (cold, drought, salt), less pesticide use, reduced post-harvest losses, conserving soil fertility, improved nutrition — Golden rice (Vitamin A).

2. Bt toxin

   Protein of Bacillus thuringiensis — an inactive protoxin crystal. It becomes active in the alkaline pH of the insect's gut → creates pores in midgut cells → the insect dies. The bacterium itself is not killed.

3. Bt cotton

   cry genes: cryIAc and cryIIAb → cotton bollworm; cryIAb → corn borer. Bt cotton, Bt corn, rice, tomato, potato, soybean.

4. RNA interference (RNAi)

   The nematode Meloidogyne incognita infects tobacco roots. Nematode-specific genes are introduced using Agrobacterium → sense + antisense RNA → dsRNA → silences the specific mRNA of the nematode → the parasite cannot survive.

5. Human insulin

   Insulin: A and B chains, linked by disulphide bridges; pro-insulin has an extra C peptide. Eli Lilly (1983) inserted the DNA sequences of the A and B chains into E. coli plasmids, produced them separately, then joined them → humulin. Earlier, insulin from animals (cattle, pig) caused allergies.

6. Gene therapy

   First done in 1990 on a 4-year-old girl — ADA (adenosine deaminase) deficiency. Functional ADA cDNA introduced into lymphocytes (retroviral vector) — periodic treatment. Permanent cure: introducing the gene into bone marrow cells at an early embryonic stage.

7. Molecular diagnosis

   Early detection: PCR (HIV, cancer mutations), ELISA (antigen–antibody), recombinant DNA, radioactive probe + autoradiography (the clone with the mutated gene does not show up).

8. Transgenic animals

   ~95% of transgenic animals = mice. Uses: study of normal physiology, disease study, biological products (α-1-antitrypsin — emphysema), vaccine safety (polio vaccine — mice), chemical safety testing. Rosie (1997) — first transgenic cow, produced milk containing human protein (2.4 g/L, α-lactalbumin).

9. Ethical issues & GEAC

   GEAC (Genetic Engineering Appraisal Committee) — decides the validity of GM research and the safety of introducing GMOs for public services.

10. Biopiracy & patents

    Biopiracy = use of bioresources without proper authorisation and without compensation. Controversy over the patent on Basmati rice (US company, 1997); also on turmeric and neem. The Indian Parliament amended the Indian Patents Bill.

The concept in depth — the why and the how. Everything stays within the NCERT syllabus.

1. Why does the Bt toxin not kill the bacterium?

   In Bacillus, the toxin exists as inactive protoxin crystals. In the alkaline pH of the insect's gut, the crystals dissolve and the toxin becomes active. The active toxin binds to the epithelial cells of the midgut and creates pores, causing the cells to swell and burst, and the insect dies. The toxin is coded by cry genes: cryIAc and cryIIAb control cotton bollworms, cryIAb controls corn borer.

2. RNAi — 'muting' the mRNA

   RNA interference is a cellular defence in all eukaryotes: a complementary dsRNA binds to a specific mRNA and prevents its translation (silencing). The nematode Meloidogyne incognita damages the roots of tobacco. Using Agrobacterium vectors, nematode-specific genes were introduced into the plant so that both sense and anti-sense RNA were produced; this dsRNA silences a specific mRNA of the nematode, and the parasite cannot survive in the transgenic host. This is a direct application of translation from Chapter 5.

3. Why was making insulin tricky?

   Insulin is made of two short polypeptide chains — A and B — linked by disulphide bridges. In the body, pro-insulin is made first, which has an extra C-peptide that is removed later. In 1983, Eli Lilly inserted the DNA sequences of the A and B chains into separate E. coli plasmids, produced the chains separately, and then joined them by disulphide bonds to make human insulin.

4. Why is ADA gene therapy not permanent?

   In 1990, a 4-year-old girl was given the first gene therapy for ADA deficiency: the patient's lymphocytes were grown in culture outside the body, functional ADA cDNA was introduced into them (using a retroviral vector), and they were returned to the body. However, these cells are not immortal, so the treatment has to be repeated periodically. If the gene producing ADA is introduced into cells at early embryonic stages, it could be a permanent cure. Other options: bone marrow transplantation and enzyme replacement therapy.

5. Testing before symptoms appear

   Conventional diagnosis (serum, urine analysis) cannot detect the pathogen at an early stage. PCR can amplify even a very small amount of DNA, so HIV in suspected AIDS patients and mutations in suspected cancer patients can be detected early. ELISA is based on antigen–antibody interaction. A radioactive probe can identify complementary DNA, and the mutated gene can be located by autoradiography.

6. Uses of transgenic animals

   Transgenic animals (over 95% of existing transgenic animals are mice) are used to: study normal physiology and disease (cancer, cystic fibrosis, Alzheimer's), produce biological products (α-1-antitrypsin — for treating emphysema), and for vaccine safety (polio vaccine) and chemical safety testing. In 1997, Rosie was the first transgenic cow; her milk was protein-rich, containing human α-lactalbumin (2.4 g/litre) — nutritionally more balanced for human babies.

Common confusions — cleared up

1. Biopatent vs Biopiracy

   Biopatent = a government-granted right over a biological invention. Biopiracy = use of a country's bio-resources or traditional knowledge without permission/compensation (e.g., the Basmati patent dispute).

2. What does GEAC do?

   The Genetic Engineering Approval Committee decides on the validity of GM research and the safety of introducing GM organisms for public services.

3. Gene therapy vs Enzyme replacement

   In enzyme replacement, the ready-made enzyme is given by injection; in gene therapy, the gene that produces the enzyme itself is introduced into the cells.

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