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How does CRISPR work?

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Quick answer

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.

Step by step

  1. A short 'guide RNA' is designed to match the target DNA sequence through base pairing.
  2. The Cas9 protein carries the guide, scans the genome, and binds where the sequence matches.
  3. Cas9 then cuts both strands of the DNA at that precise location.
  4. The cell's repair machinery either disables the gene or stitches in a new sequence supplied by scientists.

People also ask

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.