What does the term "allele" refer to in genetics?

The term "allele" refers to a version of a gene, which means that an allele can have different forms that result in variations of a trait. For instance, a single gene may have several alleles that influence traits such as flower color, eye color, or specific metabolic functions. These variations arise due to slight differences in DNA sequences at a specific locus on a chromosome, enabling the diversity of traits observed within a population.

In contrast, other choices like a type of protein or a cellular structure do not accurately describe what an allele is, as proteins are the products of gene expression and cellular structures pertain to the components of a cell itself. Additionally, while genetic sequences can be mutated, the term "allele" specifically refers to the variant forms of a gene rather than mutations broadly. Understanding alleles is crucial in genetics for studying inheritance patterns and trait variation in organisms.