cy·​to·​sine | \ ˈsī-tə-ˌsēn How to pronounce cytosine (audio) \

Definition of cytosine

: a pyrimidine base C4H5N3O that codes genetic information in the polynucleotide chain of DNA or RNA — compare adenine, guanine, thymine, uracil

Examples of cytosine in a Sentence

Recent Examples on the Web In the case of SARS-CoV-2, which has an RNA genome based on adenine, cytosine, guanine and uracil, sometimes mistakes happen. Quanta Magazine, 25 Feb. 2021 To do so, researchers typically convert a data file’s string of digital 1s and 0s into combinations of the molecule’s four bases: adenine, guanine, cytosine, and thymine. Robert F. Service, Science | AAAS, 11 Jan. 2021 All that means is that there’s a genetic variation at a certain location on your genome—for example, a cytosine base instead of thymine at position 42. Caitlin Harrington, Wired, 2 Oct. 2020 One by one each of the four bases - adenine, thymine, guanine, cytosine, or A, T, G, C - washes over the plate containing Nicholas' exons. Mark Johnson And Kathleen Gallagher, Milwaukee Journal Sentinel, 21 Dec. 2010 The four bases of virus RNA are written in an alphabet composed of nucleotide chemicals: adenine (A), cytosine (C), guanine (G) and uracil (U). Robert Lee Hotz, WSJ, 7 Sep. 2020 Instead of hooks and loops, the Velcro has the nucleotides that make up DNA: adenine, cytosine, guanine and thymine. Gaia Squarci, Smithsonian Magazine, 10 Aug. 2020 In the graphic below, cytosine is replaced with thymine. Courtney Linder, Popular Mechanics, 25 July 2020 One serves as a template, laying down sequences of the four bases that make up DNA molecules: adenine (A), thymine (T), guanine (G) and cytosine (C). Lydia Denworth, Scientific American, 3 Mar. 2020

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

See More

First Known Use of cytosine

1894, in the meaning defined above

History and Etymology for cytosine

International Scientific Vocabulary cyt- + -ose + -ine entry 2

Keep scrolling for more

Learn More About cytosine

Time Traveler for cytosine

Time Traveler

The first known use of cytosine was in 1894

See more words from the same year

Statistics for cytosine

Cite this Entry

“Cytosine.” Dictionary, Merriam-Webster, Accessed 22 Jun. 2021.

Style: MLA
MLACheck Mark Icon ChicagoCheck Mark Icon APACheck Mark Icon Merriam-WebsterCheck Mark Icon

Keep scrolling for more

More Definitions for cytosine


cy·​to·​sine | \ ˈsīt-ə-ˌsēn How to pronounce cytosine (audio) \

Medical Definition of cytosine

: a pyrimidine base C4H5N3O that codes genetic information in the polynucleotide chain of DNA or RNA — compare adenine, guanine, thymine, uracil

More from Merriam-Webster on cytosine Encyclopedia article about cytosine


Test Your Vocabulary

Return of Name that Color!

  • a light greenish blue color
  • Name that color:
True or False

Test your knowledge - and maybe learn something along the way.

 AlphaBear 2

Spell words. Make bears.

Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!