* Gene: A segment of DNA that codes for a specific protein or functional RNA molecule. Genes are responsible for traits like eye color, hair color, etc.
* Allele: A specific version of a gene. For example, the gene for eye color might have an allele for brown eyes and an allele for blue eyes. You inherit one allele from each parent.
* Chromosomes: Long, thread-like structures made of DNA. Each chromosome carries many genes.
So, a single gene has multiple alleles, but an allele itself is a single variant of that gene, not a collection of genes.
