An allele is a variation of a gene that can be expressed as a phenotype.
Explanation:
Genes are the specific sequences of DNA that code for a particular protein in organisms. When the fertilization occurs each parent contributes one chromosome which is homologous this means that both will have genes on the particular loci. The alleles of the particular genes will come together to express the trait.
Allele is an entity of gene which determines how the gene will express the particular trait like tall, short, round, wrinkle etc. It can be said that allele determines the phenotypic trait of a particular gene.
