system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How does gene activation work? Aren't genes mere blueprints? How does a gene "activate itself"?

I tried searching, but all the "polymerase" and similar terminology is over my level. All (I think) I know is that DNA is a double helix (of monomers or something) that gets cut in half when one of the "arms" is needed to make a protein.
gpt
You have a master blue print in a safe (DNA in the nucleus). You keep it there at all times because it is fragile and you will need to reference it for a really long time and it is the only copy you have, and it is huge. When certain conditions are met (a stimulus that leads to increased gene expression, there tons of possibilities like an increase in stress hormone in the blood, etc.) you make a more disposable and easier to read copy of just the section of blueprint that you need (the gene), this copy is called RNA. The copy is taken out of the safe and handed off to a team of builders (ribosomes) who follow the blue print to create a tool (protein) that will go out and do whatever job it was commissioned for (lots of different proteins do a lot of different things inside and outside of the cell).