Science word of the day: Allele

The word allele in yellow centered on a dark blue background with white oval features. — Alleles are variants of genes.

(Image credit: Yana Iskayeva via Getty Images)

Science word of the day: Allele

Pronunciation: Ah-LEEL'

What it means: Genes contain the instructions for the various proteins that determine traits, such as eye color or blood type. An allele is a specific variant of a gene. Alleles come in pairs, one from each parent. Some are dominant, meaning that copy will override any instruction from the other allele in the pair, and some are recessive, meaning there have to be two copies of that particular allele for those instructions to translate into an observable feature. Of course, not all inheritance is as simple as dominant and recessive patterns, particularly for traits that arise from combinations of hundreds of genes.

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Stephanie Pappas is a contributing writer for Live Science, covering topics ranging from geoscience to archaeology to the human brain and behavior. She was previously a senior writer for Live Science but is now a freelancer based in Denver, Colorado, and regularly contributes to Scientific American and The Monitor, the monthly magazine of the American Psychological Association. Stephanie received a bachelor's degree in psychology from the University of South Carolina and a graduate certificate in science communication from the University of California, Santa Cruz.