Biotechnology
Learn Biotechnology with notes, examples, and practice questions.
Chapter Overview
Biotechnology = biology + technology. rDNA technology made insulin production in bacteria possible at scale.
Biotechnology uses living systems and molecular biology tools to make products for medicine, agriculture, and industry. Recombinant DNA technology and PCR are core Class 12 concepts.
Principles of rDNA Technology
Restriction enzyme
Cuts at specific palindromic sequences
Vector
Plasmid with ori, selectable marker, cloning site
Host
E. coli, yeast, mammalian cells
- Isolate gene of interest (donor DNA)
- Cut with restriction endonucleases (molecular scissors) — sticky/cohesive ends
- Ligate into vector (plasmid, bacteriophage) using DNA ligase
- Transform host cell (E. coli); select with antibiotic resistance marker
- Clone and express protein product
Tools & Techniques
- PCR: amplify DNA in vitro — denature, anneal primers, extend (Taq polymerase)
- Gel electrophoresis: separate DNA by size
- Bioreactors: large-scale culture for product harvest
- ELISA: detect antigens/antibodies (diagnostic)
Applications
- Humulin: human insulin from recombinant E. coli
- Bt cotton: Bt toxin gene from Bacillus thuringiensis — pest resistance
- Gene therapy: introduce functional gene into patient cells
- Transgenic animals: models for disease, production of biologicals
Biosafety & Ethics
- GM crops: yield vs biodiversity concerns
- Biopiracy and patent issues
- GEAC regulates GM organisms in India
Solved Examples
Step-by-step solutions — read each step before checking the final answer.
Example 1: Restriction Enzyme
Why are sticky ends useful in cloning?
- 1Single-stranded overhangs can base-pair with complementary ends.
- 2Increases efficiency of ligation by DNA ligase.
Answer
Facilitate joining of donor DNA and vector
Example 2: PCR Steps
Name the three steps of one PCR cycle.
- 1Denaturation (~95°C)
- 2Annealing of primers (~50–65°C)
- 3Extension by Taq polymerase (~72°C)
Answer
Denature → Anneal → Extend
Example 3: Bt Cotton
How does Bt cotton resist bollworm?
- 1Plant expresses Bt toxin (Cry protein) from inserted gene.
- 2Insect gut alkaline pH solubilises crystal protein → pores → death.
Answer
Insecticidal protein from recombinant gene
Key Points to Remember
- ✓ Restriction enzymes: EcoRI, HindII — know palindrome concept
- ✓ Selectable marker: antibiotic resistance for transformed cell identification
- ✓ Taq polymerase is thermostable — essential for PCR
- ✓ Bioreactor: stirred-tank type most common
Exam Tips
- • Draw flowchart of rDNA steps
- • Differentiate upstream vs downstream processing
- • Know full forms: PCR, ELISA, GEAC
Formula Cheat Sheet
Quick reference — NCERT board exam formulas
rDNA Technology
- Steps:Isolate gene → restrict → ligate into vector → transform host → clone & express
- Restriction enzyme:Cuts DNA at specific palindromic sequences ; creates sticky ends
- DNA ligase:Joins DNA fragments (phosphodiester bonds)
- Vector (plasmid):ori + selectable marker + cloning site
- Selectable marker:Antibiotic resistance — identifies transformed cells
PCR & Applications
- PCR cycle:Denaturation (~95°C) → Annealing (~50–65°C) → Extension (~72°C, Taq polymerase)
- Taq polymerase:Thermostable DNA polymerase from Thermus aquaticus
- Gel electrophoresis:Separates DNA fragments by size (smaller → farther)
- Humulin:Recombinant human insulin from E. coli
- Bt cotton:Cry toxin gene from Bacillus thuringiensis → insect resistance
Practice MCQs — Biotechnology
Test your understanding with topic-wise multiple choice questions. Explanations appear after each answer.
Molecular scissors in rDNA are: