Class 12 Biology - Biotechnology

Biotechnology is the technique of using live organisms or enzymes to produce products useful to humans.

1. Principles of Biotechnology

1. Genetic Engineering: Modifying DNA to change the phenotype of host organisms.
2. Maintenance of Sterile Ambience: To grow only the desired microbe for large-scale production.

2. Tools of rDNA Technology

A. Restriction Enzymes (Molecular Scissors)

• Exonucleases: Remove nucleotides from ends.
• Endonucleases: Cut at specific points (e.g., HindII, EcoRI).
• They recognize a Palindromic sequence.

B. Cloning Vectors

Plasmids and Bacteriophages. Essential features:

• Origin of Replication (ori): Controls copy number.
• Selectable Marker: To identify transformants (e.g., antibiotic resistance).
• Cloning Sites: Recognition sites for enzymes.

3. Processes of rDNA Technology

1. Isolation of DNA.
2. Fragmentation of DNA by restriction endonucleases.
3. Isolation of desired DNA fragment using Gel Electrophoresis.
4. Ligation of DNA fragment into a vector.
5. Amplification of Gene of interest using PCR (Polymerase Chain Reaction).
   • Denaturation → Annealing → Extension.
6. Insertion of rDNA into the host.
7. Obtaining the foreign gene product in a Bioreactor.

4. Downstream Processing

The series of processes (separation and purification) that a product undergoes before being marketed.

🔬 Exam-Point Diagrams

• Structure of pBR322 vector.
• Steps of Polymerase Chain Reaction (PCR).
• A simple stirred-tank bioreactor.

Focus on the logic of Selectable Markers—it's a frequent board question! 🧬🧪