Class 12 Biology Chapter 11 Biotechnology:Principles And Processes Notes
11.1 Principles of Biotechnology
Biotechnology is based on two core principles:
Genetic Engineering
Alteration of genetic material (DNA)
Introduction of foreign genes into host organisms
Bioprocess Engineering
Large-scale production using bioreactors
Maintaining optimal conditions for growth and product formation
Recombinant Proteins Used in Medical Practice
Recombinant DNA technology allows production of therapeutic proteins in large quantities.
Important Recombinant Proteins and Uses:
Human insulin – Diabetes
Human growth hormone (hGH) – Dwarfism
Clotting factors VIII / IX – Haemophilia
tPA (Tissue plasminogen activator) – Heart attack / stroke
PDGF – Wound healing
Interferons – Viral infections
Interleukins – Immune stimulation
Hepatitis-B vaccine – Disease prevention
Herpes vaccine – Disease prevention
DNase I – Cystic fibrosis
11.2 Tools of Recombinant DNA Technology
Restriction Enzymes
Restriction enzymes are molecular scissors that cut DNA at specific sites.
Recognition site is palindromic
Example: BamHI
Produces sticky ends, useful for gene cloning
Palindromic DNA Sequences
A palindromic sequence reads the same on both strands in opposite directions.
Examples:
DNA vs Enzymes (Molecular Size)
DNA is larger than enzymes
Reason:
DNA is a long polymer of nucleotides
A small DNA segment (gene) can code for many proteins
Restriction Endonucleases in Eukaryotes
Absent in eukaryotes
Present in bacteria as a defence mechanism
Eukaryotic DNA is heavily methylated
11.3 Processes of Recombinant DNA Technology
Origin of Replication (ori)
Sequence where DNA replication begins
Controls copy number of recombinant DNA
Essential part of cloning vectors
Polymerase Chain Reaction (PCR)
PCR is an in-vitro technique to amplify DNA.
Steps of PCR:
Denaturation – dsDNA → ssDNA
Annealing – Primers bind
Extension – Taq polymerase synthesises DNA
Uses:
Gene amplification
Diagnosis
Gene cloning
Reporter Genes
Reporter genes help identify transformed cells.
Example:
lacZ gene
Transformed cells → white colonies
Non-transformed cells → blue colonies
Recombinant DNA in Meiosis
Formed during crossing over
Occurs in pachytene stage of Prophase-I (Meiosis)
Bioreactors
Bioreactors are vessels used for large-scale production.
Advantages Over Shake Flasks:
Better aeration and mixing
Temperature and pH control
Foam control system
Sampling ports
Uniform oxygen availability
Downstream Processing
Downstream processing includes all steps after product formation.
Steps:
Separation
Purification
Formulation
Clinical trials (for drugs)
Other Important Enzymes
Restriction Enzymes and DNA
Cut DNA at specific recognition sites
Produce sticky ends
Protect bacteria from viral DNA
Chitinase
Breaks down chitin (fungal cell wall)
Helps in fungal transformation
Molar Concentration of DNA
Human DNA concentration ≈ 2 mg/ml of cell extract
11.4 Summary (Exam Ready ✨)
Biotechnology combines genetic engineering and bioprocessing
Recombinant proteins are widely used in medicine
Restriction enzymes cut DNA at specific sites
PCR amplifies DNA rapidly
Bioreactors enable large-scale production
Downstream processing ensures product purity
✍️Top 10 Short Question–Answers
Q1. What is biotechnology?
Answer: Biotechnology involves the use of living organisms or their components to produce useful products.
Q2. Name the two core principles of biotechnology.
Answer: Genetic engineering and bioprocess engineering.
Q3. What is genetic engineering?
Answer: It is the alteration of genetic material by introducing foreign genes into a host.
Q4. What are restriction enzymes?
Answer: Molecular scissors that cut DNA at specific recognition sites.
Q5. What is a palindromic DNA sequence?
Answer: A sequence that reads the same on both strands in opposite directions.
Q6. What is the function of origin of replication (ori)?
Answer: It is the site where DNA replication begins and controls copy number.
Q7. What is PCR?
Answer: Polymerase Chain Reaction is an in-vitro technique to amplify DNA.
Q8. Name the enzyme used in PCR.
Answer: Taq polymerase.
Q9. What are bioreactors used for?
Answer: Large-scale production of recombinant products.
Q10. What is downstream processing?
Answer: Steps involved after product formation for purification and formulation.
📝 Long Answer Questions
Q1. Explain the principles of biotechnology.
Answer:
Biotechnology is based on two main principles:
1. Genetic Engineering
Alteration of DNA
Introduction of foreign genes into host organism
Production of recombinant DNA
2. Bioprocess Engineering
Large-scale production using bioreactors
Maintenance of optimum conditions like pH, temperature and oxygen
Ensures maximum product yield
Q2. Describe tools of recombinant DNA technology.
Answer:
Restriction enzymes:
Cut DNA at specific palindromic sites
Produce sticky ends
Example: BamHI
Vectors (with ori):
Help in replication of recombinant DNA
Polymerase Chain Reaction (PCR):
Amplifies DNA in vitro
Steps: Denaturation, Annealing, Extension
Reporter genes:
Identify transformed cells
Example: lacZ gene
Q3. Explain the role of bioreactors and downstream processing.
Answer:
Bioreactors:
Used for large-scale production
Provide proper aeration and mixing
Control pH, temperature and foam
Ensure uniform oxygen availability
Downstream processing:
Separation of product
Purification
Formulation
Clinical trials (for drugs)
📝 PYQs (Previous Year Questions)
🔹 1️⃣ Very Short Answer Questions (1 Mark)
What is biotechnology?
Name the two core principles of biotechnology.
What are restriction enzymes also called?
Name any one restriction endonuclease.
What is a palindromic DNA sequence?
What is the function of origin of replication (ori)?
Name the enzyme used in PCR.
What is PCR?
What are bioreactors used for?
What is downstream processing?
🔹 2️⃣ Short Answer Questions (2–3 Marks)
Explain genetic engineering as a principle of biotechnology.
What is bioprocess engineering?
Why are restriction enzymes called molecular scissors?
What is the significance of palindromic sequences in DNA?
Write the steps involved in PCR.
What are reporter genes? Give one example.
Why are bioreactors preferred over shake flasks?
What is the role of origin of replication in cloning vectors?
Write any two uses of PCR.
Why are restriction enzymes absent in eukaryotes?
🔹 3️⃣ Long Answer Questions (3–5 Marks)
Describe the principles of biotechnology.
Explain the tools of recombinant DNA technology.
Describe the process of recombinant DNA technology.
Explain Polymerase Chain Reaction (PCR) in detail.
Describe the role of bioreactors in industrial production.
Explain downstream processing and its importance.
Write a note on recombinant proteins used in medical practice.
🔹 4️⃣ Difference-Based PYQs (Very Important)
Genetic engineering vs Bioprocess engineering
Sticky ends vs Blunt ends
Shake flask vs Bioreactor
DNA vs RNA polymerase
Restriction enzymes vs Ligase
🔹 5️⃣ Assertion–Reason / Concept-Based PYQs
Restriction enzymes produce sticky ends. Justify.
PCR is an in-vitro method of DNA amplification. Explain.
Bioreactors ensure better yield than shake flasks. Give reason.
Recombinant proteins are important in medical practice. Explain.
Downstream processing is essential after product formation. Justify.
🔹 6️⃣ Diagram / Flowchart Based PYQs
Draw a labelled diagram of a bioreactor.
Diagram showing steps of PCR.
Flowchart of recombinant DNA technology.
❓ FAQs (5)
FAQ 1. Why are restriction enzymes absent in eukaryotes?
Because eukaryotic DNA is heavily methylated.
FAQ 2. Why are sticky ends important in cloning?
They help in joining foreign DNA with vector DNA.
FAQ 3. Why is PCR important in biotechnology?
It allows rapid amplification of DNA for diagnosis and cloning.
FAQ 4. Why are bioreactors better than shake flasks?
They provide better control of growth conditions.
FAQ 5. What is the importance of recombinant proteins in medicine?
They are used to treat diseases like diabetes, haemophilia and dwarfism.
| Chapter No. | Chapter Name | Visit |
|---|---|---|
| 1 | Reproduction in Organisms | Visit |
| 2 | Sexual Reproduction in Flowering Plants | Visit |
| 3 | Human Reproduction | Visit |
| 4 | Reproductive Health | Visit |
| 5 | Principles of Inheritance and Variation | Visit |
| 6 | Molecular Basis of Inheritance | Visit |
| 7 | Evolution | Visit |
| 8 | Human Health and Disease | Visit |
| 9 | Strategies for Enhancement in Food Production | Visit |
| 10 | Microbes in Human Welfare | Visit |
| 11 | Biotechnology: Principles and Processes | Visit |
| 12 | Biotechnology and its Applications | Visit |
| 13 | Organisms and Populations | Visit |
| 14 | Ecosystem | Visit |
| 15 | Biodiversity and Conservation | Visit |
| 16 | Environmental Issues | Visit |
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