What is an allele?

An allele is defined as a variant form of a gene. Genes, which are segments of DNA located on chromosomes, can exist in different forms. These forms are what we refer to as alleles. For example, a gene that determines flower color in a plant may have a purple allele and a white allele; these are variations that result in different traits being expressed.

Alleles contribute to the genetic diversity within a population and can affect traits such as appearance or metabolism. Because they are variations of a single gene, they can influence the same characteristic in different ways, leading to different observable traits in individuals.

While chromosomes are structures that house genes and their respective alleles, they are not equivalent to alleles themselves. Similarly, although alleles are segments of DNA, the term specifically refers to the variant forms of a given gene rather than any segment of DNA. Lastly, proteins are complex molecules made from amino acids and are not synonymous with alleles, which relate to gene expression rather than protein structure.