Biotechnology is one of the most important and scoring units of Class 12 Biology. The chapter “Biotechnology: Principles and Processes Class12 Notes” explains the fundamental tools, techniques, and steps used to manipulate genetic material for human welfare. These notes are written in simple English, strictly based on NCERT, and explained in detail so that students can easily understand concepts for CBSE board exams, competitive exams (NEET), and revision purposes. This complete guide covers definitions, principles, diagrams (description-based), and key points frequently asked in exams.
Biotechnology Principles and Processes Class12 Notes | NCERT Based + Important Questions
What is Biotechnology?
Biotechnology is the application of biological systems, living organisms, or their derivatives to develop or modify products and processes for specific use.
According to NCERT:
Biotechnology deals with techniques using live organisms or enzymes from organisms to produce products and processes useful to humans.
Key Features of Biotechnology:
- Use of living cells or enzymes
- Genetic manipulation
- Industrial-scale production
- Application in medicine, agriculture, and industry
Principles of Biotechnology
Modern biotechnology is based on two core techniques:
1. Genetic Engineering
Genetic engineering involves altering the genetic material (DNA) of an organism to introduce desirable traits.
It includes:
- Isolation of genetic material (DNA)
- Cutting DNA at specific sites
- Amplification of gene of interest
- Insertion of desired gene into a host organism
- Expression of the foreign gene
2. Maintenance of Sterile Conditions (Bioprocess Engineering)
To produce large quantities of products like antibiotics, vaccines, or enzymes, sterile conditions are required.
This is achieved by:
- Using bioreactors
- Providing optimal growth conditions
- Preventing contamination
Tools of Recombinant DNA Technology
1. Restriction Enzymes (Molecular Scissors)
Restriction enzymes cut DNA at specific recognition sequences called palindromic sequences.
Types of Restriction Enzymes:
- Exonucleases: Remove nucleotides from ends of DNA
- Endonucleases: Cut DNA at specific internal sites (most important)
Example:
- EcoRI: Isolated from Escherichia coli
After cutting, DNA fragments may have:
- Sticky ends
- Blunt ends
Sticky ends help in easy ligation.
2. Cloning Vectors
Cloning vectors are DNA molecules that carry foreign DNA into host cells and help in replication.
Characteristics of a Good Vector:
- Origin of replication (ori)
- Selectable marker genes
- Restriction sites
- Small size
Common Vectors:
- Plasmids (pBR322, pUC18)
- Bacteriophages
- Cosmids
3. Competent Host Cells
Host cells are organisms that receive recombinant DNA.
Common hosts:
- E. coli
- Yeast
- Plant and animal cells
DNA can be introduced by:
- Heat shock method
- Electroporation
- Microinjection
4. DNA Ligase
DNA ligase joins DNA fragments by forming phosphodiester bonds.
It helps in:
- Joining gene of interest with vector DNA
Processes of Recombinant DNA Technology
Step 1: Isolation of Genetic Material
DNA is isolated using enzymes like:
- Lysozyme (bacteria)
- Cellulase (plants)
DNA is purified by removing proteins and RNA.
Step 2: Cutting of DNA at Specific Sites
Restriction enzymes cut both:
- Source DNA
- Vector DNA
This creates compatible ends for ligation.
Step 3: Amplification of Gene of Interest (PCR)
PCR (Polymerase Chain Reaction) makes multiple copies of DNA.
Components of PCR:
- Template DNA
- Primers
- Taq polymerase
- dNTPs
Steps of PCR:
- Denaturation (94–95°C)
- Annealing (50–60°C)
- Extension (72°C)
Step 4: Ligation of DNA Fragments
The gene of interest is joined with vector DNA using DNA ligase.
This forms recombinant DNA.
Step 5: Insertion into Host Cell (Transformation)
Recombinant DNA is transferred into host cells.
Methods:
- Heat shock
- Electroporation
Step 6: Selection of Recombinants
Selectable marker genes (like antibiotic resistance) help identify transformed cells.
Example:
- Cells with recombinant plasmid survive on antibiotic media
Step 7: Expression of Foreign Gene
The foreign gene produces desired protein under suitable conditions
Bioreactors
Bioreactors are large vessels used for large-scale production.
Types:
- Simple stirred tank bioreactor
Functions:
- Provide oxygen
- Maintain pH and temperature
- Agitation and mixing
Downstream Processing
After production, products are:
- Separated
- Purified
- Formulated
- Marketed
This entire process is called downstream processing.
Important Terms to Remember
- Recombinant DNA
- Plasmid
- Restriction enzyme
- PCR
- Bioreactor
- Downstream processing
Exam-Oriented Key Points
- EcoRI cuts DNA at GAATTC
- PCR uses Taq polymerase
- Plasmids act as vectors
- Bioreactors ensure mass production
Important Questions (Repeated & Exam-Oriented)
Very Short Answer Questions (1 Mark)
- What is biotechnology?
- Name any one restriction enzyme.
- What is a cloning vector?
- Which enzyme is used in PCR?
- What is a plasmid?
- Define recombinant DNA.
- What is downstream processing?
- Name the host organism commonly used in genetic engineering.
Short Answer Questions (2–3 Marks)
- Explain the role of restriction enzymes in recombinant DNA technology.
- Write any two features of a good cloning vector.
- What is PCR? Mention its importance.
- Differentiate between sticky ends and blunt ends.
- What is the function of DNA ligase?
- Explain the concept of selectable marker genes.
- Write short notes on bioreactors.
Long Answer Questions (4–5 Marks)
- Describe the tools of recombinant DNA technology with suitable examples.
- Explain the process of recombinant DNA technology step by step.
- What is PCR? Explain its steps and applications.
- Describe the structure and working of a stirred tank bioreactor.
- Explain downstream processing in biotechnology.
Assertion–Reason Type Questions (Repeated in Exams)
- Assertion (A): PCR is used to amplify DNA. Reason (R): Taq polymerase is a heat-stable enzyme.
- Assertion (A): Plasmids are used as vectors. Reason (R): Plasmids have the ability to replicate independently.
Case-Based Questions (New Exam Pattern)
- A student was studying recombinant DNA technology and observed that antibiotic resistance genes are used during selection. Explain why these genes are important in the identification of recombinant cells.
Conclusion
The chapter “Biotechnology Principles and Processes Class12 Notes” is highly important from both board and competitive exam perspectives. A clear understanding of tools, techniques, and processes along with regular practice of important and repeated questions can help students score maximum marks. These notes, along with the question set, provide complete preparation material for Class 12 Biology students.