messenger RNA

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noun Genetics.
a single-stranded molecule of RNA that is synthesized in the nucleus from a DNA template and then enters the cytoplasm, where its genetic code specifies the amino acid sequence for protein synthesis. Abbreviation: mRNA
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Origin of messenger RNA

First recorded in 1960–65
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023


What is messenger RNA?

Messenger RNA, or mRNA for short, is RNA that’s used to carry DNA’s genetic code outside the cell nucleus so it can be used as the instructions to build proteins.

DNA is a large, complex molecule (macromolecule) that allows cells to function and carries the genetic code that determines the traits of a living organism. DNA is in every cell of every living thing and contains the instructions that cells need to function. RNA is a macromolecule that functions alongside DNA to help cells make proteins, among other functions.

Messenger RNA is created from a DNA template in the nucleus. An enzyme in the cell nucleus, known as RNA polymerase, unspirals the DNA and breaks the ladder in half down the middle. The enzyme then reads the nitrogen bases (the rungs of the ladder) and makes RNA in a process known as transcription. Messenger RNA carries DNA’s genetic code to structures called ribosomes in the cytoplasm (the middle layer of the cell between the nucleus and the membrane). The ribosomes “read” this code (the nitrogen base sequence), which specifies the amino acid sequence for protein synthesis—the creation of proteins. Once the protein is built, the cell destroys the mRNA.

We took a microscopic look at the differences between mRNA, RNA, and DNA, and their vital roles. Read all about it here!

Why is messenger RNA important?

In the 1950s, scientists Elliot Volkin and Lazarus Astrachan recognized a distinct form of RNA—one strongly resembling DNA but whose function they couldn’t yet determine. In 1961, Sydney Brenner, François Jacob, and Matthew Meselson determined messenger RNA’s role in protein synthesis and named the molecule based on its function as a kind of messenger.

Messenger RNA is a crucial part of the cell’s process of protein synthesis. Proteins have many essential jobs within a living thing. For example, your immune system produces proteins called antibodies to fight germs. Without mRNA, the cell would not be able to transmit protein-making instructions from DNA.

Messenger RNA is one of three three major kinds of RNA, along with ribosomal RNA (rRNA) and transfer RNA (tRNA). rRNA is a part of ribosomes that allows mRNA to function. Ribosomes produce tRNA, which brings them the needed amino acids based on the code specified by the mRNA.

Did you know ... ?

Because messenger RNA cannot replicate itself and is naturally destroyed by cells after being used, messenger RNA from viruses has been used to develop cheaper, safer antiviral vaccines. The vaccines developed to fight COVID-19 are based on mRNA vaccine technology.

What are real-life examples of messenger RNA?

This image is an illustration of the transcription process, in which messenger RNA (colored red) is made from DNA (colored purple). Their structures are similar but not identical.

Getty. Messenger RNA (mRNA) being made from DNA.

Messenger RNA is one of the three major types of RNA that students learn about in biology class. It has been used to develop vaccines.

Quiz yourself!

True or False?

Ribosomes read the code contained within messenger RNA to make proteins.

How to use messenger RNA in a sentence

British Dictionary definitions for messenger RNA

messenger RNA

biochem a form of RNA, transcribed from a single strand of DNA, that carries genetic information required for protein synthesis from DNA to the ribosomesSometimes shortened to: mRNA See also transfer RNA, genetic code
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Scientific definitions for messenger RNA

messenger RNA
[ mĕsən-jər ]

See under RNA.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.