Understand molecular scissors (restriction endonucleases), plasmid cloning vectors, Taq polymerase PCR cycles, and gene editing mechanisms.
Biotechnology combines biological systems with chemical and physical techniques to produce therapeutics, diagnostic tools, and genetically modified organisms (GMOs). It is a vital scoring chapter in Class 12 Biology and NEET examinations.
Tools of Recombinant DNA Technology: Restriction Endonucleases (e.g., EcoRI) cut DNA at specific palindromic recognition sequences (5'-GAATTC-3') producing sticky cohesive ends. DNA Ligase joins sticky ends together, while cloning vectors like plasmid pBR322 contain selectable antibiotic resistance markers (ampR, tetR) and an origin of replication (ori).
Polymerase Chain Reaction (PCR): In vitro enzymatic amplification of DNA in three consecutive steps: (1) Denaturation at 94 °C separating double strands, (2) Annealing of oligonucleotide primers at 50-60 °C, and (3) Extension at 72 °C catalyzed by heat-stable Taq Polymerase (isolated from Thermus aquaticus).
Modern Innovations like CRISPR-Cas9 utilize guide RNA and Cas9 endonuclease for precise base-pair editing. Dr. Aarzoo Saini provides step-by-step molecular biology diagrams at We-Gyaan Classes Roorkee.
Key Takeaways for Students
- Restriction endonucleases recognize specific palindromic sequences and generate sticky ends.
- Selectable markers (ampR, tetR) in plasmid pBR322 distinguish transformants from non-transformants.
- PCR involves three temperature cycles: Denaturation (94°C), Annealing (54°C), and Extension (72°C).
- Taq Polymerase remains thermally stable throughout repeated high-temperature PCR cycles.
Authored by Dr. Aarzoo Saini
Founder & Lead Educator at We-Gyaan Classes Roorkee, with over 15 years of teaching excellence in Science and Chemistry for Board Exams, NEET, JEE, and CUET.