Alleles - GCSE Biology Definition

Alleles are different versions of the same gene found on a chromosome, and they play a key role in determining an organism’s traits. In GCSE Biology, alleles can be either dominant or recessive. The combination of alleles an individual inherits from their parents influences specific characteristics, such as eye colour or blood type. For each gene, an individual human inherits two alleles—one from each parent. If both alleles are the same, the individual is homozygous; if the alleles are different, they are heterozygous. Understanding alleles is essential for learning about inheritance and genetic variation.