What is the difinition of alleles?

Answer 1

An allele is a form of a gene. For example, the allele B may lead to black fur and the allele b may lead to white fur. Both B and b are alleles for fur colour.

In general notation, dominant alleles are written with a capital letter (eg. B, T, P) and recessive alleles are written with a lower case letter (eg. b, t, p). A person will have two alleles (one from each parent) for every gene. Dominant alleles are expressed over recessive alleles.

Answer 2

Alleles are different forms of a gene that occupy the same position on a pair of chromosomes. Each organism inherits two alleles for each gene, one from each parent. Alleles can be dominant or recessive, and they determine the traits or characteristics an organism will display.

Answer 3

A different molecular form of the same gene. For instance, there is three alleles for blood type. A, B and O.