An allele is a variant form of a gene. Genes are segments of DNA that carry the instructions for making proteins and determining specific traits or characteristics in an organism.
In diploid organisms, which have two sets of chromosomes (one from each parent), alleles can exist in pairs. For example, an individual might inherit one allele for a particular trait from one parent and a different allele for the same trait from the other parent. These versions can be dominant, recessive, or codominant, influencing how traits are expressed.
For example, consider a gene that determines flower color in a plant. One allele may code for red flowers (dominant), while another allele codes for white flowers (recessive). The combination of these alleles (e.g., two red alleles, one red and one white allele, or two white alleles) will determine the flower color of the offspring.
In summary, alleles are crucial for genetic diversity and are fundamental to the study of inheritance and evolution.