Homology directed repair

Homology directed repair (HDR) is like fixing a piece of broken LEGO with the exact same piece.

When something goes wrong with our DNA, our cells need to fix it. HDR is one way that our cells do this. They use a template to make the repairs, just like you might use a picture on the box to fix your LEGO model.

Imagine your DNA is like a long string of LEGO pieces. When one piece breaks, HDR can use a copy of the exact same piece to fix it. The copy will be used as a template to replace the piece that's broken.

Our cells have the special tools to make the copy piece that they need for HDR. It's called a "homologous" piece, which means it's the same kind of piece as the one that's broken.

So, how does it work? First, the cells use a special enzyme to cut both the broken piece and the copy piece. Then, the cells use the copy piece as a template to make a new piece to fill in the space left by the broken piece.

The cells then attach the new piece to the broken one, so now the DNA is fixed! This is how HDR can fix mistakes or damage in our cells' DNA.