Final answer:
Genes are functional lengths of DNA that provide genetic information for building proteins. They are located on chromosomes.
Step-by-step explanation:
A gene is a functional length of DNA that provides the genetic information necessary to build a protein. Its function is to code for the production of a specific protein or RNA molecule, which carries out a particular function in the cell. The location of a gene can vary depending on the organism, but it is usually found on a chromosome. Chromosomes are structures within the cell that contain DNA and genes, and they are responsible for organizing and packaging the genetic information.
For example, in humans, the gene for eye color (called OCA2) is located on chromosome 15. This gene provides the information for the production of a protein involved in the production and transport of melanin, the pigment responsible for eye color.