Scientists Say: Allele

When genes come in two or more versions, they have a special name

Brown eyes, blue eyes and green eyes all see perfectly well. Their different colors are due to variations, or alleles, in two genes. 

Joaquin Villaverde/Flickr/ (CC BY-NC-SA 2.0)

Allele (noun, “Ah-LEE-uhl”)

One of two or more alternative forms of a gene. Genes are segments of DNA molecules that contain instructions to make proteins. But some of these genes have more than one version that can still get the job done. For example, different alleles determine whether your eyes are brown, blue or green.

In a sentence

Sea urchins have multiple alleles of different genes that help them live in more acidic water.

Follow Eureka! Lab on Twitter

Power Words

(for more about Power Words, click here)

allele One of two or more alternative versions of a gene.

DNA  (short for deoxyribonucleic acid) A long, double-stranded and spiral-shaped molecule inside most living cells that carries genetic instructions. In all living things, from plants and animals to microbes, these instructions tell cells which molecules to make.

gene   (adj. genetic) A segment of DNA that codes, or holds instructions, for producing a protein. Offspring inherit genes from their parents. Genes influence how an organism looks and behaves.

Bethany Brookshire is the staff writer at Science News for Students. She has a Ph.D. in physiology and pharmacology and likes to write about neuroscience, biology, climate and more. She thinks Porgs are an invasive species.

More Stories from Science News for Students on Genetics