What do we call variations of a gene that can lead to different traits in an organism?

The variations of a gene that can lead to different traits in an organism are called alleles. Alleles are different versions of a gene that may produce distinguishable phenotypic effects. For instance, a single gene can have multiple alleles, each responsible for a different variant of a trait, such as flower color in plants or blood type in humans.

While genotype refers to the genetic makeup of an organism, which includes all its alleles, it does not specifically address the variations themselves. Phenotypes, on the other hand, refer to the observable characteristics exhibited by an organism, which can be influenced by the alleles present, but they do not define the variations of the genes. Gametes are the reproductive cells (sperm and eggs) that carry alleles to the next generation but are not direct indicators of gene variations. Thus, alleles distinctly highlight the genetic variations leading to the diversity of traits within a species.