Cytosin

Part of speech: noun

Definitions

1. A pyrimidine compound that forms one of the four nucleobases in DNA and RNA, pairing with guanine in the genetic code
2. One of the nitrogenous bases that make up nucleotides in living cells, appearing in both deoxyribonucleic and ribonucleic acids
3. A nitrogen-containing molecule that serves as a building block of genetic material by bonding with other nucleobases in the structure of chromosomes and viral particles

Etymology: The name comes from the Greek "kytos," meaning a hollow vessel or container, which is also the root of the biological term "cyto-" for cell. Chemists building a name for this compound added it to the "cyt-" stem, and the "-ine" ending that marks many nitrogen-containing organic compounds, so the name points to the cell where the molecule was found. Cytosine is one of the four nucleobases in DNA and RNA, and it pairs with guanine. The name was built from parts that describe its source and chemical family rather than its structure, so the word tells you where the compound was first isolated, not what it looks like.