What is definition of an allele?

An allele is one of two or more alternative forms of a gene that arise by mutation and are found at the same place on a chromosome.

Here's a breakdown:

* Gene: A segment of DNA that codes for a specific trait (like eye color).

* Allele: A variation of that gene. For example, the gene for eye color might have alleles for brown eyes, blue eyes, green eyes, etc.

* Mutation: A permanent change in the DNA sequence. Mutations can create new alleles.

Key points about alleles:

* You inherit one allele from each parent.

* These alleles may be the same (homozygous) or different (heterozygous).

* The combination of alleles you inherit determines the trait you express.

* Different alleles can lead to variations in a trait, which contributes to the diversity of life.

Example:

* The gene for eye color is located on chromosome 15.

* One allele for eye color might code for blue eyes (let's call it "b").

* Another allele for eye color might code for brown eyes (let's call it "B").

You could have the following allele combinations:

* BB: Brown eyes

* Bb: Brown eyes (because brown is dominant over blue)

* bb: Blue eyes

This example demonstrates how different alleles contribute to variations in a trait.