What is a Gene?
A gene is a unit of genetic material (DNA) that is located at a certain position within a chromosome. Each gene carries unique information that is inherited, i.e. passed down from generation to generation.
The number of genes is a particular characteristic of each species. For example, humans have approximately 20,000 genes organized into 46 chromosomes, although the exact number is not yet known. This whole set of genes is called genome.