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.
When I was at medical school, which was a long time ago, I remember learning a little bit about gene therapy and it being talked about then.
From BBC ● Oct. 9, 2026
A study published in Frontiers in Immunology and led by Professor Colin Smith from the University of Surrey examined how supplementation affected gene activity in the blood.
From Science Daily ● Oct. 8, 2026
The firm also pointed to US chemist and biologist David Liu for developing "precision gene editing technologies that directly edit DNA in living systems".
From Barron's ● Oct. 7, 2026
In the age of AI and gene sequencing, we still catch cancer one organ at a time.
From The Wall Street Journal ● Oct. 1, 2026
Long gone were the days when someone could be born with the time-traveling gene and go unaccounted for.
From "Glitch" by Laura Martin
Port of Los Angeles Executive Director Gene Seroka said struggling carriers approached the port to request help earlier this year.
From The Wall Street Journal ● Oct. 8, 2026
Rusty Goffe began his film career in the Gene Wilder movie, before later appearing in the original Star Wars, the Harry Potter films and Doctor Who.
From BBC ● Sep. 23, 2026
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
Faye was waitressing at the bowling alley one Friday night when Gene wandered in with a pack of his friends.
From "Educated" by Tara Westover
Coupled with abundant haplotype diversity, tetraploid potato may therefore contain thousands of -gene analogues.
From Nature ● Jul. 13, 2011
While genes linked to it can run in families, not everyone who inherits one of these will necessarily experience a reaction with anaesthesia.
From BBC ● Oct. 10, 2026
In lymphoma cells, the protein can stay stuck in the "on" position, continually suppressing death-related genes and allowing malignant cells to keep multiplying.
From Science Daily ● Oct. 8, 2026
The study included only male mice, examined a single type of fat deposit, and focused specifically on genes, proteins, and molecular signals associated with fat breakdown.
From Science Daily ● Oct. 8, 2026
When an acetyl tag is added to BCL6, the protein loses its ability to suppress the cell-death genes downstream from it.
From Science Daily ● Oct. 8, 2026
We still do not know what causes the difference of outcomes between these three women—but it is some combination of age, exposures, other genes, and bad luck.
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.
