the goal of gene therapy is to insert a what? into cells to correct a genetic disorder?

Answer 1

The goal of gene therapy is to insert a healthy copy of a gene into a cell that has a faulty gene. If the gene doesn’t integrate properly, it produces its protein for only a short time before being turned off or broken down within the cell. To ensure a long-term cure, the gene must position itself into a chromosome, where it remains permanently integrated. It will be passed on when the cell divides.

Answer 2

How about "a gene"?