Alleles are different versions of the same gene that sit at the same spot (locus) on a chromosome and can produce different forms of a trait, like eye color or blood type.

Quick Scoop: What are alleles?

Think of a gene as a ā€œrecipeā€ in your DNA, and alleles as different flavors of that recipe (like chocolate vs vanilla cake) that still make the same kind of thing but with a twist. For most genes, you carry two allelesā€”one inherited from your mother and one from your fatherā€”which together make up your genotype for that gene.

Key points in plain language

  • An allele is one of two or more versions of a gene at a specific location on a chromosome.
  • You usually have two alleles for each gene: one from each parent.
  • If both alleles are the same, you are homozygous for that gene; if they are different, you are heterozygous.
  • Alleles can be dominant , recessive , or sometimes codominant , influencing which trait you actually see (your phenotype).
  • Many visible traits (like hair color) and medical traits (like some inherited diseases) depend on which alleles you carry.

A quick example

  • In classic pea-plant experiments, purple vs white flowers were controlled by different alleles of a single geneā€”one allele gave purple flowers, another gave white.
  • In humans, the ABO blood group is controlled by alleles of one gene: A, B, and O; different allele combinations (like AO, AB, BO, OO) give different blood types.

In short, alleles are alternative versions of a gene that help explain why siblings can share parents yet look and respond to diseases differently.

Information gathered from public forums or data available on the internet and portrayed here.