Question

What is an allele?

Answer 1

Alleles are actually possible alternative forms of the gene which results when the gene gets mutated.

Explanation:

All diploid organisms e.g humans have two alleles at a given locus on a pair of homologous chromosomes. Both are inherited from each of the two parents. We can say these are kind of gene partners and occur always in pairs(in case of mammals) as genes do.

Alleles can be dominant, recessive or codominant to each other. They relate to genes in that they directly influence the work of gene i.e to determine the trait.

For example: the gene that control the hair colour occur in its different versions(alleles) i.e allele for brown colour, alleles for black colour etc. The allele which would be dominant would be expressed as a specific trait(hair colour) in a recipient individual.

Different alleles may not always result in phenotypic differences; if a recessive allele is paired with a dominant allele, the genotype may differ from two dominant alleles paired together, but the phenotype would be the same.

For more info, give a read to the link given below:
socratic.org/questions/how-are-alleles-and-traits-related

Hope it helps...