An overview of the fundamental principles and applications of molecular biology techniques in research and laboratory settings.
Introduction to Molecular Biology Techniques
Key concepts, common methods, and practical considerations
Molecular biology explores the structure and function of nucleic acids (DNA, RNA) and proteins. Modern techniques enable researchers to:
| Goal | Typical Technique(s) | What It Reveals |
|---|---|---|
| DNA/RNA isolation | Phenol‑chloroform extraction, silica‑column kits | Pure nucleic acids for downstream work |
| Amplification | PCR, RT‑PCR, qPCR, LAMP | Generate many copies of a specific sequence |
| Cloning & manipulation | Restriction‑enzyme cloning, Gibson assembly, CRISPR‑Cas9 | Insert, delete, or edit DNA in vectors or genomes |
| Sequencing | Sanger, Illumina (NGS), Oxford Nanopore | Determine nucleotide order |
| Expression analysis | Northern blot, RT‑qPCR, RNA‑seq, microarrays | Measure RNA levels |
| Protein analysis | Western blot, ELISA, mass spectrometry, flow cytometry | Detect and quantify proteins |
| Functional assays | Reporter genes, RNAi, CRISPR screens | Test gene function in cells or organisms |
| Step | Principle | Tips |
|---|---|---|
| Cell lysis | Disrupt membranes (detergents, mechanical shear) | Keep samples on ice; add protease/RNase inhibitors |
| Nucleic‑acid purification | Bind nucleic acids to silica in presence of chaotropic salts; wash; elute | Use ethanol precipitation for large volumes; verify purity (A260/A280) |
| Quality check | Spectrophotometry, agarose gel electrophoresis, Bioanalyzer | A260/A280 ≈ 1.8 (DNA) or 2.0 (RNA); RIN > 7 for RNA‑seq |
| Component | Function |
|---|---|
| Template DNA | Source of target sequence |
| Primers | Short oligos (18‑30 nt) that flank the region |
| DNA polymerase | Thermostable enzyme (e.g., Taq, Phusion) |
| dNTPs | Building blocks |
| Buffer + Mg²⁺ | Optimizes enzyme activity |
| Cycling conditions | Denaturation → Annealing → Extension (30‑35 cycles) |
| Variant | When to use | Key feature |
|---|---|---|
| RT‑PCR | RNA → cDNA | Reverse transcriptase added |
| qPCR (real‑time PCR) | Quantify DNA/RNA | Fluorescent dyes (SYBR) or probes (TaqMan) |
| Multiplex PCR | Detect several targets simultaneously | Multiple primer sets, careful optimization |
| LAMP | Field diagnostics | Isothermal amplification, high speed |
| Component | Role