cytosine

American  

[sahy-tuh-seen, -zeen, -sin] / ˈsaɪ təˌsin, -ˌzin, -sɪn /

noun

Biochemistry.

1. a pyrimidine base, C 4 H 5 N 3 O, that is one of the fundamental components of DNA and RNA, in which it forms a base pair with guanine. C

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cytosine British  

/ ˈsaɪtəsɪn /

noun

1. a white crystalline pyrimidine occurring in nucleic acids; 6-amino-2-hydroxy pyrimidine. Formula: C 4 H 5 N 3 O See also DNA RNA

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cytosine Scientific  

/ sī′tə-sēn′ /

1. A pyrimidine base that is a component of DNA and RNA, forming a base pair with guanine. Chemical formula: C ₄ H ₅ N ₃ O.

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Etymology

Origin of cytosine

< German Cytosin (1894); cyto-, -ose ², -ine ²

Example Sentences

Importantly they also discovered all five nitrogenous bases — adenine, guanine, cytosine, thymine, and uracil — that are necessary to build DNA and RNA.

From Salon • Jan. 30, 2025

These include 14 of the 20 amino acids that life on Earth uses to build proteins and all four of the ring-shaped molecules that make up DNA - adenine, guanine, cytosine and thymine.

From BBC • Jan. 29, 2025

Nucleotides are composed of three distinctive parts: a sugar molecule, a phosphate group and one of the four nucleobases adenine, thymine, guanine and cytosine.

From Science Daily • Mar. 8, 2024

For example, exposure to water can cause a chemical reaction called deamination that changes the nucleotide cytosine such that it appears to be the nucleotide thymine upon analysis.

From Scientific American • Aug. 25, 2023

For the past two years this DNA was said to have the strange property of lacking cytosine, a feature obviously impossible for our model.

From "Double Helix" by James D. Watson