Here's a breakdown:

* Genes: These are segments of DNA that contain the instructions for building and maintaining an organism.

* DNA: This is a long, complex molecule that carries genetic information.

* Nucleus: This is a membrane-bound organelle found in eukaryotic cells (cells with a nucleus). It houses the cell's DNA, which is organized into structures called chromosomes.

Think of it like this: the nucleus is a safe where the blueprints (genes) for building and running the cell (the organism) are kept safe.