An allele is a specific version or variation of a gene. For each gene, you inherit one allele from each parent, and these two alleles determine how a specific trait is expressed.

September 27, 2025

What Is The Difference Between Dominant And Recessive Alleles

Q: Can someone carry a trait without it being visible?

Yes. A person with one dominant and one recessive allele (heterozygous) is called a carrier for the recessive trait. They will show the dominant trait but can pass the recessive allele to their children.

Learn the key distinction between dominant and recessive alleles in genetics. Understand how traits are expressed based on the versions of genes inherited.

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Dominant vs. Recessive Alleles Explained

The main difference is how they express a trait. A dominant allele is a version of a gene that will produce a certain physical trait (phenotype) even if only one copy is present. A recessive allele will only produce a trait if two copies are present, and it is masked if a dominant allele is also present.

An Example with Eye Color

Imagine the gene for eye color has a dominant allele for brown eyes (B) and a recessive allele for blue eyes (b). If a person inherits one of each (Bb), they will have brown eyes because the brown allele is dominant. To have blue eyes, a person must inherit two copies of the recessive allele (bb).

Frequently Asked Questions

What is an allele?

Can someone carry a trait without it being visible?