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 nucleus contains a cell's DNA and plays a central role in regulating gene activity.
From Science Daily ● Aug. 31, 2026
Stevia also altered gene expression, but the changes were weaker and did not persist beyond one generation.
From Science Daily ● Aug. 31, 2026
Immunotherapies haven’t proven effective against pancreatic cancer, which is almost always driven by a mutation in the RAS gene family.
From The Wall Street Journal ● Aug. 26, 2026
The problem was the shape of the protein generated by the mutated gene.
From The Wall Street Journal ● Aug. 26, 2026
Did every gene have a unique chromosomal “address”? Did genes overlap?
From "The Gene" by Siddhartha Mukherjee
In the Chicago Tribune, Gene Siskel called it “the worst major motion picture I’ve seen in almost eight years on the job.”
From The Wall Street Journal ● Aug. 27, 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
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
The move is likely a case of “buy on the rumor, sell on the news,” according to Gene Munster, managing partner at Deepwater Asset Management.
From MarketWatch ● Jul. 2, 2026
I can’t help but turn, and sure enough, Gene is one table up and one over giving me a look like he isn’t close to done.
From "Popcorn" by Rob Harrell
Coupled with abundant haplotype diversity, tetraploid potato may therefore contain thousands of -gene analogues.
From Nature ● Jul. 13, 2011
The researchers also investigated genes involved in digesting the chitin found in insect exoskeletons.
From Science Daily ● Aug. 27, 2026
Among North Eurasian populations, chitinase genes contain mutations associated with a reduced ability to digest insect exoskeletons.
From Science Daily ● Aug. 27, 2026
In the early 1980s, scientists identified a small number of mutated genes that drove most human cancers.
From The Wall Street Journal ● Aug. 26, 2026
By making certain stress-related genes easier to activate, early adversity may leave the brain more reactive and less able to tolerate future stress.
From Science Daily ● Aug. 26, 2026
If genes were, indeed, independent particles of information, then it should be possible to select, purify, and manipulate these particles independently from one another.
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.
