A DNA code for one hereditary trait is called a gene.

Here's a breakdown:

* DNA: The molecule that carries the genetic instructions for an organism.

* Gene: A segment of DNA that provides the instructions for building a specific protein or functional RNA molecule. These proteins and RNA molecules determine traits.

* Hereditary trait: A characteristic passed down from parents to offspring, influenced by genes.

For example, a gene for eye color might contain the instructions for producing a specific pigment protein. The version of this gene you inherit from your parents determines the color of your eyes.