🌸Chapter 9
Biotechnology: Principles and Processes
(Summary Notes)
1. Important Definitions
|
Term |
Definition |
|
Biotechnology |
The use of living organisms or their products to modify
human health, agriculture, and industry. |
|
Recombinant DNA (rDNA) |
DNA molecules formed by joining DNA from two different
sources. |
|
Vector |
DNA molecule used to carry foreign DNA into a host (e.g.,
plasmid, bacteriophage). |
|
Plasmid |
Small, circular DNA in bacteria, independent of chromosomal
DNA, used as a vector. |
|
Restriction enzyme |
Enzyme that cuts DNA at specific sequences (palindromic). |
|
DNA ligase |
Enzyme that joins DNA fragments by forming phosphodiester
bonds. |
|
Competent cell |
Bacterial cell capable of taking up foreign DNA. |
|
Transformation |
Uptake of foreign DNA by a host cell. |
|
Transfection |
Introduction of foreign DNA into eukaryotic cells. |
|
PCR (Polymerase Chain Reaction) |
Technique to amplify specific DNA sequences in vitro. |
|
Bioreactor |
Controlled vessel for large-scale microbial or cell
culture. |
|
Downstream processing |
Purification, separation, and formulation of a product
after fermentation. |
|
Selectable marker |
Gene used to identify transformed cells (e.g., antibiotic
resistance). |
|
Blue-white screening |
Method to distinguish recombinant bacteria from
non-recombinant using lacZ gene. |
2. Key Concepts
A. Tools of Biotechnology
- Restriction enzymes: Cut DNA at specific sequences
- DNA ligase: Joins DNA fragments
- Vectors: Carry foreign DNA (plasmids, bacteriophages)
- Host cells: Usually E. coli,
yeast, or mammalian cells
- PCR & Gel electrophoresis: DNA amplification &
separation
B. Recombinant DNA Technology Steps
1.
Isolation
of gene of interest
2.
Cutting
DNA & vector
(restriction enzymes)
3.
Ligation (DNA ligase)
4.
Introduction
into host
(transformation/transfection)
5.
Selection
& screening
(antibiotics, blue-white)
6.
Expression
of protein (if
needed)
7.
Downstream
processing
(purification & formulation)
C. Vectors
- Plasmid: Small, circular, Ori,
selectable markers, multiple cloning sites
- Expression vector: Contains promoter for gene
expression
- Bacteriophage: Larger inserts, infects
bacteria
- Cosmid: Hybrid vector with λ phage
and plasmid features
D. Applications of rDNA Technology
1.
Medicine: Insulin, hGH, vaccines, interferon
2.
Agriculture: Bt cotton, Golden rice,
herbicide-resistant crops
3.
Industry: Enzymes (amylase, protease),
biofuels, antibiotics
4.
Diagnostics: PCR, DNA fingerprinting, pathogen
detection
E. PCR (Polymerase Chain Reaction)
- Purpose: Amplify specific DNA fragment
- Steps: Denaturation → Annealing →
Extension
- Enzyme: Taq polymerase (heat-stable)
- Applications: Genetic testing, cloning,
forensic science
F. Gel Electrophoresis
- DNA separated based on size in
agarose gel
- Smaller fragments move faster
- Visualized using ethidium
bromide under UV
G. Bioreactors
- Maintain optimal conditions:
pH, temp, oxygen, nutrients
- Types: Stirred-tank
(mechanical), airlift (air bubbles)
- Used for large-scale
protein/enzyme production
H. Downstream Processing
1.
Cell
removal
2.
Filtration/centrifugation
3.
Chromatography
(purification)
4.
Concentration
& formulation
5.
Quality
control
3. Important Diagrams
1.
Steps
of Recombinant DNA Technology
Gene of interest → Restriction enzyme
→ Vector DNA → Ligase → Recombinant DNA → Host cell → Selection → Expression → Purification
2.
Blue-White
Screening
Plasmid with lacZ gene
Foreign DNA inserted → lacZ
disrupted → White colonies (recombinant)
No insertion → lacZ active → Blue
colonies (non-recombinant)
3.
PCR
Steps
Denaturation (95°C) → Annealing (55°C)
→ Extension (72°C) → Repeat cycles → Amplified DNA
4.
Gel
Electrophoresis
DNA loaded in wells → Electric field
→ Smaller fragments move faster → DNA bands visualized
4. NCERT Keywords for Quick Revision
- Recombinant DNA
- Vector, plasmid, bacteriophage,
cosmid
- Restriction enzymes, sticky
ends, blunt ends
- DNA ligase
- Competent cells,
transformation, transfection
- PCR, Taq polymerase
- Gel electrophoresis
- Bioreactor, downstream
processing
- Selectable marker, antibiotic
resistance
- Blue-white screening
5. Quick Facts
- EcoRI cuts: GAATTC
- pBR322: Common plasmid vector
- Taq polymerase: From Thermus aquaticus
- Applications: Insulin, Bt crops, vaccines,
enzymes
- Downstream processing ensures purity and efficacy
- PCR cycles: ~20–35 to get millions of
copies
✅ Tips for Exam Prep
- Focus on diagrams and
label each step
- Remember key enzymes and
their functions
- Use flowcharts for
recombinant DNA, PCR, and downstream processing
- Revise examples of
applications in medicine, agriculture, and industry
- Practice definitions and
keywords for 1–2 mark questions
