How does CRISPR-Cas9 work in gene editing?

CRISPR-Cas9 is a tool used to change genes in living cells. It works like tiny scissors that can cut DNA at a specific spot so that scientists can add, remove, or fix a piece of genetic code.

Here’s how it works step by step:

1. Finding the target gene:
   Scientists choose the part of the DNA they want to edit.
2. Making a guide RNA:
   A small piece of RNA is made that matches the DNA sequence scientists want to change. This guide RNA helps find the exact spot in the DNA.
3. Bringing in Cas9:
   The Cas9 enzyme attaches to the guide RNA. Together, they move along the DNA until they find the matching sequence.
4. Cutting the DNA:
   When the guide RNA finds the right spot, Cas9 cuts the DNA there.
5. DNA repair:
   The cell tries to repair the cut. During this process, scientists can:
   • Turn off a gene, or
   • Insert a new piece of DNA to fix or change the gene.

In simple words, CRISPR-Cas9 works like a “cut and paste” tool for genes — it finds a specific DNA part, cuts it, and helps replace or repair it.