NCERT Chapter 10: Biotechnology and Its Applications
By Persue Classes
Asfak Hossain, Biology Expert
BIOTECHNOLOGICAL APPLICATIONS IN AGRICULTURE
Why apply biotech to agriculture?
Land and water constraints + growing population → need higher, stable yields with less environmental cost.
Modern tools allow targeted traits (pest resistance, stress tolerance, nutrition).
Three Approaches to Increase Food Production
- Agro-chemical based agriculture — Use of fertilisers, pesticides. Works but costly for poor farmers and pollutes environment.
- Organic agriculture — Eco-friendly but lower yields.
- Genetically engineered crop-based agriculture — Uses genetic modification for higher yield, pest/stress resistance, better nutrition. (Our focus)
Why GE crops are needed: Green Revolution tripled food supply, but demand keeps rising.
Conventional breeding is slow and sometimes cannot give the traits we need.
GM crops can combine traits quickly and precisely.
Tissue Culture & Micropropagation
Tissue culture = growing plant tissues or cells in sterile, nutrient-rich medium.
Totipotency = ability of a single cell to grow into a whole plant.
Medium contains:
- Carbon source (sucrose)
- Inorganic salts
- Vitamins, amino acids
- Growth regulators (auxins, cytokinins)
Micropropagation = rapid production of many genetically identical plants (somaclones).
Examples: tomato, banana, apple (commercial scale).
Virus-free plants: Meristem culture works because meristems (apical/axillary) are virus-free. Used for banana, sugarcane, potato.
Why meristem culture for virus-free plants?
Meristems are rapidly dividing and usually free of viruses because virus movement lags behind growth. Remove the meristem and culture it — you can regenerate a virus-free plant (used for banana, sugarcane, potato).
মেরিস্টেম কালচার এমন একটি পদ্ধতি যা ভাইরাসমুক্ত উদ্ভিদ তৈরি করতে ব্যবহার করা হয়। এই কৌশলটি মেরিস্টেমে দ্রুত বিভাজনশীল কোষ ব্যবহার করে, যা প্রায়শই ভাইরাস-মুক্ত থাকে, এমনকি যদি পুরো গাছটি সংক্রামিত হয়। মেরিস্টেমের দ্রুত বৃদ্ধি ভাইরাসের প্রতিলিপি এবং ছড়িয়ে পড়ার ক্ষমতাকে ছাড়িয়ে যায়।
How does meristem culture facilitate the regeneration of virus-free plants?
- Exploiting the Virus-Free Nature of Meristems:
- Viruses typically spread systemically through the plant via the vascular system (e.g., phloem).
- However, the meristematic tissues are characterized by a very rapid rate of cell division, often outpacing the rate of viral replication and movement.
- This rapid growth essentially outruns the virus, leaving the apical meristem region relatively free of infection.
Protoplast: plant cell with cell wall removed (only plasma membrane intact). How to make protoplasts: Digest cell walls using cellulase and pectinase enzymes in isotonic buffer (to prevent bursting). Filter and collect protoplasts.
Somatic hybridisation: Fusion of protoplasts (cells without cell walls) from different varieties → somatic hybrids (e.g., Pomato). Not all hybrids are commercially useful.
Genetically Modified Organisms (GMOs)
Definition: Plants, animals, bacteria, fungi whose genes have been artificially altered.
Benefits : Tolerance to abiotic stress (cold, drought, salt, heat).
- Pest resistance → less pesticide use.
- Reduced post-harvest losses.
- Better mineral use → soil fertility lasts longer.
- Enhanced nutritional value (e.g., Golden Rice – Vitamin A enriched).
Bt Crops
Bt crops & pest resistance — mechanism explained in detail Source: Bacillus thuringiensis (Bt) — soil bacterium producing crystalline insecticidal proteins (Cry proteins, δ-endotoxins) during sporulation.
How it works:
01
Bt plant contains cry gene → plant expresses Cry protoxin in tissues (leaves, stems, fruit).
02
Insect ingests plant tissue containing protoxin.
03
In insect midgut (alkaline pH ~ 9–11), protoxin is solubilized and proteases cleave it into an active toxin fragment.
04
Active toxin binds to specific receptors (cadherin-like proteins) on midgut epithelial cells.
05
Pore formation disrupts osmotic balance → cell swelling, lysis → leakage of gut contents → septicemia and death.
Specificity: Cry toxins bind only to receptors found in target insect groups (Lepidoptera, Coleoptera, Diptera). Human gut is acidic and lacks receptors — so cry toxins are non-toxic to humans.
Genes / examples: cryIAc for cotton bollworm; cryIAb for corn borer. (Different Cry proteins target different insect groups.)
Resistance management
Insects can evolve resistance. Farmers are advised to grow refuges (non-Bt plants nearby) so susceptible insects survive and mate with any resistant insects — diluting resistance alleles.
পোকামাকড় দ্রুত কীটনাশক প্রতিরোধী হয়ে উঠতে পারে, বিশেষ করে একই ধরনের কীটনাশক বারবার ব্যবহারের কারণে. প্রতিরোধের মাত্রা কমানোর জন্য কৃষককদের আশ্রয়স্থল (refuges) তৈরি করতে পরামর্শ দেওয়া হয়। এর ফলে দুর্বল পোকামাকড় বেঁচে থাকে এবং শক্তিশালী প্রতিরোধী পোকামাকড়ের সাথে প্রজনন করে, যা প্রতিরোধ জিনকে (resistance alleles) হ্রাস করে.
RNAi (আরএনএআই) দ্বারা কীটপতঙ্গ নিয়ন্ত্রণ
RNAi হল একটি প্রাকৃতিক কোষীয় প্রক্রিয়া যা জিনের প্রকাশ নিয়ন্ত্রণ করে। এতে ডাবল-স্ট্র্যান্ডেড আরএনএ (dsRNA) ব্যবহার করা হয়, যা নির্দিষ্ট জিনের কার্যকারিতাকে নীরব করতে পারে। RNAi প্রক্রিয়াটি বিভিন্ন উপায়ে কীটপতঙ্গ নিয়ন্ত্রণে ব্যবহার করা যেতে পারে।
RNA Interference (RNAi) for Pest Resistance
Big idea: RNAi uses a complementary RNA molecule to silence a gene by destroying its mRNA or blocking translation. Molecular steps (mammals/plants/nematodes): dsRNA (double-stranded RNA) introduced or produced in cell (plants can be engineered to produce dsRNA).
কীভাবে এই প্রক্রিয়াটি কাজ করে?
১. dsRNA খণ্ডিত হওয়া: কোষের মধ্যে থাকা ডাইসার এনজাইম (Ribonuclease III এনজাইমের একটি প্রকার) লম্বা dsRNA কে ছোট ছোট siRNA তে ভেঙে দেয়, যার দৈর্ঘ্য সাধারণত ২১-২৩ নিউক্লিওটাইড হয়ে থাকে.
২. RISC গঠন: এই siRNA অণুগুলি একটি প্রোটিন কমপ্লেক্সের সাথে যুক্ত হয়, যাকে আরএনএ-ইনডিউসড সাইলেন্সিং কমপ্লেক্স বা RISC (RNA-induced silencing complex) বলা হয়.
৩. লক্ষ্য mRNA সনাক্তকরণ: RISC কমপ্লেক্সের মধ্যে থাকা siRNA (যা এখন গাইড স্ট্র্যান্ড নামে পরিচিত) একটি নির্দিষ্ট mRNA অণুকে সনাক্ত করে। এই siRNA এর নিউক্লিওটাইড ক্রম সেই লক্ষ্য mRNA-এর নিউক্লিওটাইড ক্রমের পরিপূরক হয়, অর্থাৎ তারা একে অপরের সাথে আবদ্ধ হতে পারে
৪. mRNA ধ্বংস বা Translation বন্ধ:
* mRNA ধ্বংস: RISC কমপ্লেক্সে আর্গোনট (Argonaute) নামক এক ধরনের প্রোটিন থাকে. যখন RISC তার লক্ষ্য mRNA এর সাথে আবদ্ধ হয়, তখন আর্গোনট প্রোটিন সেই mRNA কে কেটে টুকরো টুকরো করে দেয়, ফলে সংশ্লিষ্ট প্রোটিন তৈরি হওয়া বন্ধ হয়ে যায়.
* অনুবাদ/Translation বন্ধ: কিছু ক্ষেত্রে, siRNA এবং mRNA এর মধ্যে যদি পুরোপুরি মিল না থাকে, তাহলে mRNA সরাসরি ধ্বংস না হয়ে অনুবাদ প্রক্রিয়া বন্ধ হয়ে যায়. S
* mRNA ধ্বংস: RISC কমপ্লেক্সে আর্গোনট (Argonaute) নামক এক ধরনের প্রোটিন থাকে. যখন RISC তার লক্ষ্য mRNA এর সাথে আবদ্ধ হয়, তখন আর্গোনট প্রোটিন সেই mRNA কে কেটে টুকরো টুকরো করে দেয়, ফলে সংশ্লিষ্ট প্রোটিন তৈরি হওয়া বন্ধ হয়ে যায়.
* অনুবাদ/Translation বন্ধ: কিছু ক্ষেত্রে, siRNA এবং mRNA এর মধ্যে যদি পুরোপুরি মিল না থাকে, তাহলে mRNA সরাসরি ধ্বংস না হয়ে অনুবাদ প্রক্রিয়া বন্ধ হয়ে যায়. S
৫. ফলাফল: এই প্রক্রিয়ার ফলে লক্ষ্য জিনের প্রোটিন তৈরি হওয়া বন্ধ হয়ে যায়, যার ফলে সেই জিনের কার্যকলাপ বন্ধ হয়ে যায় বা কমে যায় (Gene silencing).
সংক্ষেপে, RNAi প্রক্রিয়ায়, dsRNA প্রথমে siRNA তে রূপান্তরিত হয়, তারপর RISC কমপ্লেক্স দ্বারা সেই siRNA ব্যবহার করে লক্ষ্য mRNA কে ধ্বংস করা হয় অথবা তার অনুবাদ প্রক্রিয়া বন্ধ করে দেওয়া হয়, যার ফলে সংশ্লিষ্ট প্রোটিন তৈরি হয় না এবং জিনের প্রকাশ (gene expression) নিয়ন্ত্রিত হয়
01
Dicer enzyme dices dsRNA into small interfering RNAs (siRNAs, ~21–23 nucleotides).
02
siRNA duplex unwound; guide strand loaded into RISC (RNA-induced silencing complex).
03
RISC uses guide strand to bind complementary mRNA.
04
Argonaute (in RISC) slices the target mRNA → mRNA degraded → no translation → gene silenced.
In plants and nematodes, silencing signal can spread systemically.
- There’s a tiny worm-like pest called Meloidogyne incognita (a nematode) that attacks plant roots and makes them sick.
- Scientists wanted to stop it without using harmful chemicals.
What they did:
- They found a very important gene in the nematode — one it needs to survive and infect plants.
- They made the tobacco plant produce a special piece of RNA (dsRNA) that matches that nematode gene.
2.When the nematode eats the plant’s roots, it also eats this special RNA.
3. Inside the nematode, this RNA blocks the important gene so it can’t make the protein it needs.
4. The nematode becomes weak or dies, and the plant stays healthy.
In short:
The plant is taught to make a “silent weapon” inside itself that only hurts the bad pest and keeps the plant safe — like giving the pest a “broken instruction” so it can’t live.
The plant is taught to make a “silent weapon” inside itself that only hurts the bad pest and keeps the plant safe — like giving the pest a “broken instruction” so it can’t live.
Agricultural use: generate plants that produce dsRNA against pest/nematode genes — ingestion by pest triggers gene silencing, disables essential genes → pest dies or becomes sterile.
Examples (agriculture)
Golden Rice — engineered to produce β-carotene (provitamin A) in rice endosperm to combat vitamin A deficiency. (Early construct used daffodil phytoene synthase and a bacterial desaturase; later versions improved with maize gene).
Bt cotton — widely adopted (benefit: less pesticide spraying; challenge: resistance management, regulatory & socio-economic debates).
Virus-resistant
Genetically Engineered Insulin
Why make insulin using biotechnology?
Before the 1980s, insulin came from the pancreas of pigs and cows.
Problem:
- Could cause allergic reactions because animal insulin isn’t 100% identical to human insulin.
- Supply was limited — you’d need millions of animals to meet the growing demand.
So scientists decided: “Why not make human insulin in bacteria using recombinant DNA technology?”
🧬 Structure of human insulin
Insulin has two short protein chains:
- Chain A
- Chain B
These two chains are connected by special chemical links called disulfide bonds.
In the human body, insulin is first made as a single, longer protein called proinsulin:
Chain B — C-peptide — Chain A
Later, enzymes remove the C-peptide, leaving the mature insulin.
Two main methods scientists used to produce it
Method A – Separate Chain Method (Eli Lilly, early 1980s)
- Scientists made two artificial genes — one for Chain A, one for Chain B.
- Each gene was inserted into the DNA of two separate E. coli bacteria.
- Each bacterium produced only one chain of insulin.
- Scientists purified both chains from the bacteria.
- In the lab, they joined the chains together chemically by forming the correct disulfide bonds.
Result → Active human insulin.
Analogy: Like baking two separate cake layers and then sticking them together with icing.
Method B – Proinsulin Method (Later improvement)
- Scientists made one artificial gene for proinsulin (A + C + B all in one).
- Inserted into a host (bacteria or yeast) that could fold the protein correctly.
- The host cell made proinsulin as one piece.
- Scientists removed the C-peptide using enzymes → got mature insulin.
Advantage: No need to join two chains manually.
Folding happens naturally inside the host cell.
Analogy: Like baking one whole cake and then cutting away the extra crust to get the final shape.
Gene Therapy
Method to treat genetic diseases by inserting functional gene copies.
Example: ADA deficiency (enzyme needed for immune function missing).
- ADA’s job is to break down certain molecules called deoxyadenosine (a byproduct when DNA is broken down in cells).
- Without ADA, deoxyadenosine builds up in the body.
- This buildup is toxic to developing lymphocytes (T cells, B cells, NK cells — your immune soldiers).
- Result: severe combined immunodeficiency (SCID) — the immune system can’t fight infections.
Options:
- Bone marrow transplant or enzyme replacement.
Gene therapy:
- Remove patient lymphocytes → insert ADA gene via retroviral vector → return to patient.
- STEPS:
Doctors collect the person’s own hematopoietic stem cells (HSCs) — these are bone marrow cells that can make all blood and immune cells. Using the patient’s own cells avoids rejection.
They remove the (retrovirus) virus’s harmful parts and load it with a healthy ADA gene. Then they mix the delivery trucks with the patient’s HSCs so the healthy gene gets put into those cells’ DNA.
The modified stem cells are tested to make sure they carry the correct gene and are safe. They may be grown briefly so enough corrected cells are available.
The corrected HSCs are infused back into the patient (like replanting the seed stock). These cells move to the bone marrow and start producing immune cells that now make ADA.
With ADA now produced by the new immune cells, the toxic molecules are cleared, and the patient gradually rebuilds a working immune system. Over time this can greatly reduce infections and dependence on enzyme injections.
- If inserted into embryonic cells → permanent cure possible.
Molecular Diagnosis
Early detection is crucial.
Techniques:
- PCR: amplifies DNA of pathogens (e.g., HIV detection before symptoms).
- DNA/RNA probes: bind to specific mutated gene sequences.
- ELISA: detects antigens or antibodies in infections.
- Blotting techniques: Southern blot — DNA detection (probe hybridization).
- Northern blot — RNA detection.
- Western blot — protein detection using antibodies.
TRANSGENIC ANIMALS
Transgenic Animals
1. What does “transgenic” mean?
Transgenic animal = An animal whose DNA has been deliberately changed by adding a foreign gene into its genome.
The foreign gene can come from:
- A different species (e.g., human gene into a mouse)
- Or even the same species but altered.
The purpose: To give the animal new traits that it did not naturally have.
1. How are transgenic animals made?
Scientists insert the desired gene into the fertilised egg (zygote) or early embryo of the animal.
This is usually done using:
- Microinjection (injecting gene into nucleus)
- Viral vectors (using harmless viruses to carry the gene into the cell)
The embryo is then implanted into a surrogate mother → baby is born with the gene in every cell.
ETHICAL ISSUES
Need for Regulation
Unregulated manipulation can harm ecosystems.
GEAC (India) decides on validity/safety of GM research & release.
Patents & Biopiracy – NCERT Easy Explanation
1. What is a Patent?
A patent is a legal right given to an inventor.
It means no one else can make, use, or sell the invention without permission.
In biotechnology, patents can be given for:
- A new process (e.g., a special way to insert a gene into a plant)
- A new product (e.g., a GM crop)
- A combination of genes (gene construct)
Example: If a company develops a drought-resistant crop using its own genetic engineering method, it can patent it.
1. What is Biopiracy?
Bio = life (plants, animals, microorganisms, traditional knowledge about them)
Piracy = stealing or using without permission
Biopiracy happens when:
- Companies or scientists take biological resources or traditional knowledge from another country.
- They make a product and patent it without giving credit or sharing benefits with the local people or country.
Why is it wrong?
- Local communities or farmers have developed and preserved these resources for generations.
- It’s unfair for outsiders to make money without sharing benefits.
1. NCERT Examples
Basmati Rice Case (1997)
A US company patented varieties of Basmati rice grown in India.
India challenged it, and the claim was reduced — proving India’s rights over its native crop.
Neem
Used in India for centuries as a natural pesticide.
A foreign company patented neem-based products.
India fought the case and the patent was cancelled.
Turmeric
Known in India for wound healing.
US patent granted for this “discovery”.
India showed it was traditional knowledge → patent cancelled.
1. Why is this an Ethical Issue?
- Unfair to farmers: They lose control over seeds and may have to pay for something they once grew freely.
- Corporate control: A few companies can control food supply.
- Loss of sovereignty: A country’s biodiversity belongs to its people, not outsiders.
1. How India Protects Itself
Patent laws were changed to prevent foreign companies from patenting Indian biodiversity and traditional knowledge.
India set up a Traditional Knowledge Digital Library (TKDL) — a database to prove that certain uses are already known and not “new inventions”.
Mnemonic for NCERT Examples – BTN B → Basmati rice
T → Turmeric
N → Neem
lets practice:
From JENPAS UG 2022 Paper
- Q44 – "Which of the following is used as a vector for gene transfer into higher plants?"
Options: (A) Agrobacterium tumefaciens, (B) E. coli, (C) Yeast, (D) Bacillus thuringiensis
- Q45 – "Cry genes are obtained from which organism?"
Options: (A) Agrobacterium tumefaciens, (B) Bacillus thuringiensis, (C) Tobacco mosaic virus, (D) Salmonella typhi
- Q46 – "Which of the following is the first transgenic cow producing human protein enriched milk?"
Options: (A) Dolly, (B) Rosie, (C) Clonaid, (D) Tracy
From 2023 Paper
- Q39 – "In Bt cotton, the Bt toxin present in plant tissue as protoxin is converted into active toxin due to:"
Options: (A) Acidic pH of insect gut, (B) Alkaline pH of insect gut, (C) Action of digestive enzymes of insect, (D) Both B and C
- Q40 – "Which vector is used in the construction of the first recombinant DNA molecule?"
Options: (A) Ti plasmid, (B) pBR322, (C) pSC101, (D) λ phage
- Q41 – "The genetically engineered bacteria used to produce human insulin is:"
Options: (A) Bacillus subtilis, (B) E. coli, (C) Agrobacterium, (D) Saccharomyces cerevisiae
From 2024 Paper
- Q42 – "Golden rice is rich in:"
Options: (A) Vitamin A, (B) Vitamin C, (C) Iron, (D) Protein
- Q43 – "Bt toxin is coded by genes named as:"
Options: (A) cry, (B) Bt, (C) BtA, (D) BtX
- Q44 – "Who produced the first recombinant DNA molecule?"
Options: (A) Watson & Crick, (B) Herbert Boyer & Stanley Cohen, (C) Paul Berg, (D) Kary Mullis
NEET 2024
Q. The capacity to generate a whole plant from any cell of the plant is called:
Q. The capacity to generate a whole plant from any cell of the plant is called:
- Micropropagation
- Differentiation
- Somatic hybridization
- Totipotency
NEET 2024
Q. Given below are two statements:
Q. Given below are two statements:
- Statement I: Bt toxins are insect-group specific and coded by a gene cryIAc.
- Statement II: Bt toxin exists as inactive protoxin in Bacillus thuringiensis.
NEET 2023
Q. Thermostable DNA polymerase used in PCR was isolated from:
A. Thermus aquaticus
B. Escherichia coli
C. Agrobacterium tumefaciens
D. Bacillus thuringiensis.
Q. Thermostable DNA polymerase used in PCR was isolated from:
A. Thermus aquaticus
B. Escherichia coli
C. Agrobacterium tumefaciens
D. Bacillus thuringiensis.
NEET 2023
Q. Ligation of foreign DNA at which site will result in loss of tetracycline resistance of pBR322?
A. Pst I
B. Pvu I
C. Eco RI
D. Bam HI.
Q. Ligation of foreign DNA at which site will result in loss of tetracycline resistance of pBR322?
A. Pst I
B. Pvu I
C. Eco RI
D. Bam HI.
NEET 2022 (Phase 2)
Q. Which of the following methods is not commonly used for introducing foreign DNA into the plant cell?
A. Bacteriophages
B. Agrobacterium-mediated transformation
C. Gene gun (biolistic method)
D. ‘Disarmed pathogen’ vectors.
Q. Which of the following methods is not commonly used for introducing foreign DNA into the plant cell?
A. Bacteriophages
B. Agrobacterium-mediated transformation
C. Gene gun (biolistic method)
D. ‘Disarmed pathogen’ vectors.
NEET 2025: Polymerase chain reaction (PCR) amplifies DNA following the equation. What is the formula for the number of DNA molecules after 'n' cycles of PCR?
- (1) N2
- (2) 2n
- (3) 2n+1
- (4) 2N2
NEET 2025: Silencing of specific mRNA is possible via RNAi because of -.
- (1) Complementary dsRNA
- (2) Inhibitory ssRNA
- (3) Complementary tRNA
- (4) Non-complementary ssRNA
NEET 2025: The blue and white selectable markers have been developed which differentiate recombinant colonies from non-recombinant colonies on the basis of their ability to produce colour in the presence of a chromogenic substrate. Given below are two statements about this method:
- Statement I: The blue coloured colonies have DNA insert in the plasmid and they are identified as recombinant colonies.
- Statement II: The colonies without blue colour have DNA insert in the plasmid and are identified as recombinant colonies.
- (1) Both Statement I and Statement II are correct
- (2) Both Statement I and Statement II are incorrect
- (3) Statement I is correct but Statement II is incorrect
- (4) Statement I is incorrect but Statement II is correct
NEET 2025: Which of the following enzyme(s) are NOT essential for gene cloning?
A. Restriction enzymes
B. DNA ligase
C. DNA mutase
D. DNA recombinase
E. DNA polymerase
Choose the correct answer from the options given below:
(1) C and D only (2) A and B only (3) D and E only (4) B and C only
NEET 2024 (Re-Examination)
The Bt toxin in genetically engineered Bt cotton kills the pest by:
A. Creating pores in the midgut
B. Damaging the respiratory system
C. Degenerating the nervous system
D. Altering the pH of body fluids
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