ribonucleic acid

[ rahy-boh-noo-klee-ik as-id, -kley-, -nyoo-, rahy- ]
/ ˈraɪ boʊ nuˈkli ɪk ˈæs ɪd, -ˈkleɪ-, -nyu-, ˌraɪ- /
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noun Biochemistry.
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Sometimes ribose nucleic acid .

Origin of ribonucleic acid

First recorded in 1930–35; ribo(se) + nucleic acid
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2022


What is ribonucleic acid?

Ribonucleic acid—better known by the abbreviation RNA—is a large, complex molecule (macromolecule) that functions alongside DNA (deoxyribonucleic acid) to help cells make proteins.

DNA is a macromolecule that allows cells to function and carries the genetic code that determines the traits of a living organism. Among other things, RNA works with DNA to make proteins, which are required for many essential functions within living things. During this process, RNA acts as a kind of copy of the DNA that carries its genetic information outside of the cell nucleus.

RNA also carries the genetic information of many viruses.

Like DNA, RNA is a nucleic acid, which means it is made of a phosphate, a sugar, and nitrogen bases.

RNA consists of one long strand of sugars and phosphates and the nitrogen bases, which form base pairs. The result resembles a ladder with just one side. By comparison, DNA has two long strands of sugars and phosphates, with the base pairs between them, making it look like a spiraled ladder (a double helix). RNA has three of the same nitrogen bases found in DNA—adenine (A), guanine (G), and cytosine (C). Instead of thymine (T), though, RNA has uracil (U).

DNA contains the instructions that cells need to make proteins. 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. The RNA sequence matches the sequence from the DNA strand except that in RNA, adenine is paired with uracil instead of thymine, and the sugar deoxyribose is substituted with ribose.

There are three major kinds of RNA. Messenger RNA (mRNA) is created from a DNA template in the nucleus and then carries the genetic code to structures called ribosomes in the cytoplasm (the middle layer of the cell between the nucleus and the membrane), where it specifies the amino acid sequence for protein synthesis. Ribosomal RNA (rRNA) is a part of ribosomes that allows messenger RNA to function. Transfer RNA (tRNA) transports specific amino acids to ribosomes during protein synthesis.

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

Why is ribonucleic acid important?

DNA and RNA are ancient, but their discovery was relatively recent. In 1869, chemist Friedrich Miescher documented a kind of molecule that had never been studied before—nucleic acid. It wasn’t until around the 1930s that the terms ribonucleic acid and deoxyribonucleic acid began to be used, with the abbreviation RNA gaining use in the 1940s. In the 1950s, the work of biophysicist Rosalind Franklin and biologists James Watson and Francis Crick revealed DNA’s double helix structure. The function of RNA began to be further understood during the 1950s and 60s as scientists began to understand the role of messenger RNA.

This understanding is still developing. Until quite recently, RNA’s role was thought to be largely limited to assisting with protein synthesis in its forms as messenger RNA, transfer RNA, and ribosomal RNA. However, scientists are continuing to discover new types of RNA and more functions that RNA performs in the body. For example, recent discoveries suggest that there are several types of RNA that regulate how many proteins the ribosomes produce.

Did you know ... ?

Some viruses completely lack DNA and instead their genetic information is contained entirely within ribonucleic acid. COVID-19 is this type of virus, known as an RNA virus. RNA viruses are more adaptable and are much more likely to mutate than DNA viruses.

What are real-life examples of ribonucleic acid?

Unlike DNA, which takes the form of a double helix, ribonucleic acid consists of a single strand, as pictured in this illustration.

Getty. Ribonucleic acid (RNA) chain.

Most biology students learn about RNA alongside DNA. Our understanding of the role of RNA within the cell is still expanding.


Quiz yourself!

True or False?

One of the main functions of ribonucleic acid is using the information from DNA in the creation of proteins.

How to use ribonucleic acid in a sentence

British Dictionary definitions for ribonucleic acid

ribonucleic acid
/ (ˌraɪbəʊnjuːˈkliːɪk, -ˈkleɪ-) /

the full name of RNA

Word Origin for ribonucleic acid

C20: from ribo (se) + nucleic acid
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

Medical definitions for ribonucleic acid

ribonucleic acid
[ rī′bō-nōō-klēĭk, -klā- ]

The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.

Scientific definitions for ribonucleic acid

ribonucleic acid
[ rī′bō-nōō-klēĭk ]

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

Cultural definitions for ribonucleic acid

ribonucleic acid
[ (reye-boh-nooh-klee-ik) ]

See RNA.

The New Dictionary of Cultural Literacy, Third Edition Copyright © 2005 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.