The structures located in the nucleus and containing DNA are called chromosomes.

Here's a breakdown:

* Nucleus: The control center of the cell, containing genetic material.

* DNA: Deoxyribonucleic acid, the molecule carrying genetic instructions.

* Chromosomes: Tightly packed structures of DNA and proteins, containing genes.

So, within the nucleus, DNA is organized into chromosomes, which are responsible for carrying and transmitting genetic information.