Science
How does CRISPR work?
CRISPR works like molecular find-and-replace for DNA. A guide molecule is programmed to match a specific gene sequence, and a protein called Cas9 follows it to that exact spot and cuts the DNA — letting scientists disable a gene or paste in a new one as the cell repairs the cut.
See it in motion.
Watch a 2-minute animated lesson that shows exactly how CRISPR works.
Step by step
- 1A short 'guide RNA' is designed to match the target DNA sequence through base pairing.
- 2The Cas9 protein carries the guide, scans the genome, and binds where the sequence matches.
- 3Cas9 then cuts both strands of the DNA at that precise location.
- 4The cell's repair machinery either disables the gene or stitches in a new sequence supplied by scientists.
Frequently asked questions
- What does CRISPR stand for?
- Clustered Regularly Interspaced Short Palindromic Repeats — DNA patterns bacteria use as an immune defense, which scientists repurposed into an editing tool.
- Is CRISPR used in medicine?
- Yes. It underlies approved and experimental therapies for conditions like sickle cell disease, editing cells to correct or compensate for a faulty gene.
- Why is CRISPR more precise than older methods?
- The guide RNA can be reprogrammed to almost any sequence, making it far cheaper, faster, and easier to target than earlier gene-editing techniques.