Here's a breakdown:

* DNA (Deoxyribonucleic Acid): A long, complex molecule that contains the genetic instructions for building and maintaining an organism.

* Genes: Segments of DNA that code for specific traits or characteristics.

* Chromosomes: Structures within the nucleus of a cell that are made up of tightly coiled DNA and proteins. Each chromosome contains many genes.

Think of it like this:

* DNA: The blueprint for life, containing all the instructions.

* Genes: Specific instructions within the blueprint.

* Chromosomes: The organized packages of blueprints, ensuring all the instructions are kept together and passed on correctly.

So, DNA is the building block of chromosomes, which are crucial for carrying and transmitting genetic information.