amino acid


Definition of amino acid 

: an amphoteric organic acid containing the amino group NH2 especially : any of the various amino acids having the amino group in the alpha position that are the chief components of proteins and are synthesized by living cells or are obtained as essential components of the diet

Examples of amino acid in a Sentence

Recent Examples on the Web

Leucine is the most important amino acid for initiating and signaling pathways that stimulate muscle protein growth and recovery, Pritchett explains. Sara Angle, Outside Online, "Pea Protein Is the Best Protein," 19 June 2018 Rice and beans are a good example of complimentary proteins, because the amino acids that are missing from beans are found in rice and vice versa., "What’s the Deal With Complete and Incomplete Protein—and Does It Even Matter?," 10 Apr. 2018 But tyrosine is just one of the 20 amino acids normally found in protein. Bradley J. Fikes,, "Superstar cancer researcher Tony Hunter of Salk Institute wins award, makes new finding," 4 Apr. 2018 Acrylamide is the product of a chemical reaction that happens between certain sugars and the amino acid asparagine when the food is heated. Brigit Katz, Smithsonian, "California Coffee Companies Must Display Cancer Warning Label, Judge Rules," 30 Mar. 2018 Hysolli explains that, rather than synthesize every nucleotide in my Y chromosome, Church’s team will focus on discrete genetic units, called codons, that determine what kind of amino acids (and, eventually, proteins) are produced by a cell. David Ewing Duncan, WIRED, "The Next Best Version of Me: How to Live Forever," 27 Mar. 2018 Some fungi also produce the amino acids α-aminoisobutyric acid and isovaline, which are rare on Earth but often found in carbon-containing asteroids. Adam Mann, Science | AAAS, "NASA ‘clean’ room is contaminated with fungus," 23 Mar. 2018 The Stardust recovery mission found organics and glycine - one of the simplest amino acids. Jamie Seidel, Fox News, "Wild new alien theory emerges," 28 June 2018 Two of them involved pretreating collagen samples from the bones, but two others involved separating single amino acids from the samples and then radiocarbon dating those isolated compounds. Kiona N. Smith, Ars Technica, "New study adds evidence to debate over the only known Clovis burial," 18 June 2018

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'amino acid.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

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First Known Use of amino acid

1897, in the meaning defined above

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amino acid


amino alcohol


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Last Updated

11 Nov 2018

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Time Traveler for amino acid

The first known use of amino acid was in 1897

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More Definitions for amino acid

amino acid


English Language Learners Definition of amino acid

biology : any one of many acids that occur naturally in living things and that include some which form proteins

amino acid

ami·​no acid | \ə-ˈmē-nō-\

Kids Definition of amino acid

: any of various acids containing carbon and nitrogen that are building blocks of protein and are made by living plant or animal cells or are obtained from the diet

amino acid


Medical Definition of amino acid 

: an amphoteric organic acid containing the amino group NH2 especially : alpha-amino acid

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Spanish Central: Translation of amino acid

Nglish: Translation of amino acid for Spanish Speakers Encyclopedia article about amino acid

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