CRISPR-Cas9 is a gene editing tool adapted from a bacterial immune system. It works like molecular scissors guided by GPS.
**Components:** 1. **Guide RNA (gRNA)** — a ~20-nucleotide sequence that matches your target DNA 2. **Cas9 protein** — an enzyme that cuts DNA
**Process:** 1. You design a gRNA matching the DNA you want to edit 2. Cas9 + gRNA complex scans the genome until it finds the matching sequence 3. Cas9 cuts both strands of DNA at that location 4. The cell repairs the cut — either disrupting the gene (knockout) or inserting new DNA (if you provide a template)
**Why it's revolutionary:** Previous gene editing tools were slow and expensive. CRISPR cuts the time from months to days and costs from millions to thousands of dollars.