A segment of DNA, occupying a specific place on a chromosome, that is the basic unit of heredity. Genes act by directing the production of RNA, which determines the synthesis of proteins that make up living matter and are the catalysts of all cellular processes. The proteins that are determined by genetic DNA result in specific physical traits, such as the shape of a plant leaf, the coloration of an animal's coat, or the texture of a person's hair. Different forms of genes, called alleles, determine how these traits are expressed in a given individual. Humans are thought to have 20,000 to 25,000 genes; bacteria have between 500 and 6,000.
What is a gene? A gene is a sequence of nucleotides along a strand of DNA that a cell nucleus uses to produce proteins. Genes determine the specific traits of an organism. DNA (deoxyribonucleic acid) is a large molecule that is shaped like a double helix sometimes described as a twisty ladder. The rungs of the ladder are made of molecules called nucleotides. These rungs, or bases, are arranged in a specific order that creates a set of instructions, which is known as a gene. When the body needs to do something or build something, it often requires a protein. Genes are the instructions that the cells read for how to build proteins. Proteins have very specific jobs, so scientists name genes based on what job their linked proteins are designed to do. For example, hair proteins come from hair genes, while eye proteins come from eye genes. Every living organism has genes. Animals, plants, fungi, bacteria, and even the humble amoeba all have genes. The more closely related two organisms are, the more similar their genes will be. For example a dog and a wolf, which are from the same genus, will have similar genes, while a dog and a human, which are not part of the same genus, will have much different genes from each other.
First recorded in 1911; from German Gen (1909), apparently abstracted from -gen -gen ( def. ); introduced by Danish geneticist Wilhelm L. Johannsen (1857–1927)
Microscopic, yet powerful, a gene is segment of DNA, the molecule that stores the code for building living bodies. A gene is a single unit of genetic information, stored on twisting strands in every cell of every living being. In sexual reproduction, the parents' genes mix together to make the child. Although people would like to think that genes code for discrete traits, like friendliness or mathematical genius, that's not the case. Genes control the color of your eyes and the shape of your toes, not your weird personality.
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Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
Researchers at Gladstone Institutes now report that TBX5 has another important role beyond controlling gene activity.
From Science Daily ● Aug. 13, 2026
There really is a fearless gene circulating through his blood.
From Los Angeles Times ● Aug. 12, 2026
He said the new findings provide unusually strong evidence that natural selection acted on this gene in the Andes after potato cultivation began.
From Science Daily ● Aug. 10, 2026
Most types are caused by an altered gene being passed to a child by their parents and blood tests can be used to confirm a diagnosis.
From BBC ● Aug. 9, 2026
Three profoundly destabilizing scientific ideas ricochet through the twentieth century, trisecting it into three unequal parts: the atom, the byte, the gene.
From "The Gene" by Siddhartha Mukherjee
Billy Gene Mills was elected to the Los Angeles City Council in 1963 and served until 1974.
From Los Angeles Times ● Jul. 16, 2026
These days, even buying “a starter home just seems so daunting,” Gene White, a 27-year-old who works in communications, told MarketWatch.
From MarketWatch ● Jul. 9, 2026
One time he was playing at a private club in New York where on the neighbouring court Hollywood actors Gene Wilder and Sidney Poitier were filming a movie.
From BBC ● Jul. 7, 2026
Memorable cinematic roles have included a corrupt police officer in the Harrison Ford thriller "Witness" and a comedy turn in Wes Anderson's eccentric "The Royal Tenenbaums," opposite Gene Hackman.
From Barron's ● Jul. 1, 2026
The Boston editor called Gene Roberts, his boss in New York, for guidance.
From "Most Dangerous: Daniel Ellsberg and the Secret History of the Vietnam War" by Steve Sheinkin
Coupled with abundant haplotype diversity, tetraploid potato may therefore contain thousands of -gene analogues.
From Nature ● Jul. 13, 2011
People carrying more weight tended to show greater changes in genes involved in fat metabolism, while leaner volunteers showed stronger effects on inflammation.
From Science Daily ● Aug. 13, 2026
They also tracked which genes became active in different regions of the brain.
From Science Daily ● Aug. 12, 2026
Ms. Gray, then 34, was the first person to receive treatment based on the Crispr method of editing genes.
From The Wall Street Journal ● Aug. 10, 2026
Researchers have identified genes in Tibetan dogs that allow them to function in oxygen-poor conditions that would challenge breeds from lower elevations.
From Science Daily ● Aug. 10, 2026
And second, some genes are activated by external triggers or by random chance.
From "The Gene" by Siddhartha Mukherjee
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
