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.
Looking to grow your vocabulary? Check out this interactive, curated word list from our team of English language specialists at Vocabulary.com – one of over 17,000 lists we've built to help learners worldwide!
Interested in learning more words like this one? Our team at Vocabulary.com has got you covered! You can review flashcards, quiz yourself, practice spelling, and more – and it's all completely free to use!
Want to remember this word for good? Start your learning journey today with our library of interactive, themed word lists built by the experts at Vocabulary.com – we'll help you make the most of your study time!
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
The analysis pointed unexpectedly to the MAL gene.
From Science Daily ● Sep. 19, 2026
Knowing the gene behind AnWj gives blood specialists something they did not previously have: a direct genetic way to search for people who inherit AnWj-negative blood.
From Science Daily ● Sep. 19, 2026
Shares of Ultragenyx Pharmaceutical rose 13% to $14.50 after the Food and Drug Administration granted commercial approval to the biotech firm’s gene therapy for pediatric patients with a rare neurodevelopmental disease.
From The Wall Street Journal ● Sep. 17, 2026
How quickly the liver can processes the caffeine depends on a single gene – known as CYP1A2.
From BBC ● Sep. 17, 2026
If a scientist had been asked what a gene was made of, how it accomplished its function, or where it resided within the cell, there would be few satisfactory answers.
From "The Gene" by Siddhartha Mukherjee
Gene activity also revealed improvements in several biological features associated with aging, including reduced inflammation and less decline in the body's ability to repair and regenerate tissue.
From Science Daily ● Sep. 12, 2026
Gene Seroka, executive director of the Port of Los Angeles, said more than two-thirds of cargo moving in and out of the port is carried by trucks.
From Los Angeles Times ● Sep. 4, 2026
Gene White, a 28-year-old in Chicago, told MarketWatch his parents benefited from “economic serendipity.”
From MarketWatch ● Sep. 2, 2026
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
Gene regulation works through the transcription of DNA into RNA—which depends on base pairing.
From "The Gene" by Siddhartha Mukherjee
Coupled with abundant haplotype diversity, tetraploid potato may therefore contain thousands of -gene analogues.
From Nature ● Jul. 13, 2011
By changing which genes cells expressed and then testing whether AnWj appeared, the scientists could build a much stronger case that MAL was the missing piece.
From Science Daily ● Sep. 19, 2026
The team also observed weaker interactions between genes and nearby regulatory elements that normally help control whether those genes are switched on or off.
From Science Daily ● Sep. 13, 2026
The team compared genetic patterns associated with GLP1R activity with genes found in men who have androgenetic alopecia, the inherited form of hair loss that typically affects the top and front of the scalp.
From Science Daily ● Sep. 13, 2026
Instead, it folds into a complex three-dimensional structure that helps determine which genes are accessible and active.
From Science Daily ● Sep. 13, 2026
We do deny that...geneticists will see genes under the microscope....The hereditary basis does not lie in some special self-reproducing substance.
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.
