* DNA is the molecule of heredity, but it's not the basic unit. Think of it this way: DNA is like a blueprint, containing the instructions for building an organism.

* Genes are the basic units of heredity. They are specific segments of DNA that code for a particular trait or characteristic.

Here's a breakdown:

* DNA: A long, complex molecule that carries the genetic instructions for building and maintaining an organism.

* Genes: Specific segments of DNA that contain the code for a particular protein or functional RNA molecule, which in turn influences a particular trait.

* Chromosomes: Structures made of DNA and proteins that contain genes. Eukaryotes have their DNA organized into multiple chromosomes.

In summary: DNA is the blueprint, genes are the individual instructions within the blueprint, and chromosomes are the structures that hold these instructions together.