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.
There really is a fearless gene circulating through his blood.
From Los Angeles Times ● Aug. 12, 2026
Regeneron’s gene therapy to cure a rare form of deafness treats so few children that the company decided to make the treatment free.
From The Wall Street Journal ● 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
Small RNA molecules and patterns of gene activity in the blood also changed, particularly in biological pathways associated with brain function.
From Science Daily ● Aug. 9, 2026
The gene, Schrödinger posited, had to be made of a peculiar kind of chemical; it had to be a molecule of contradictions.
From "The Gene" by Siddhartha Mukherjee
Little Richard’s version of the movie’s title song pinned 13-year-old Jeff “to the back of his seat,” the authors tell us, but nothing hit him like Gene Vincent’s “Be-Bop-a-Lula.”
From The Wall Street Journal ● Jul. 30, 2026
He said that the franchise's longevity was due to "all the people like you and your parents and your grandparents, because of their intelligence and their sensitivity and their vision" in supporting Gene Roddenberry's concept.
From Barron's ● Jul. 26, 2026
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
My father, Gene, was one of those young men who somehow manage to seem both solemn and mischievous.
From "Educated" by Tara Westover
Coupled with abundant haplotype diversity, tetraploid potato may therefore contain thousands of -gene analogues.
From Nature ● Jul. 13, 2011
Critics of that theory have long argued that humans are a product of both genes and environment, and that disaggregating the two is impossible.
From The Wall Street Journal ● Aug. 21, 2026
A few minutes later he added, “He probably gave me the good genes to survive lol … Guided the bullets or something.”
From Slate ● Aug. 20, 2026
The researchers identified particular variants that influenced the female-biased expression of two genes linked to systemic lupus erythematosus.
From Science Daily ● Aug. 20, 2026
Maternal age effects may be controlled by epigenetic processes that change how genes are used rather than by mutations that alter the underlying DNA sequence.
From Science Daily ● Aug. 19, 2026
If genes were discrete particles specifying one trait, then how could this property be reconciled with the occurrence of human characteristics, say, height or skin color, in continuous curves?
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.
