Nucleotide

noun (countable)

/ˈnjuːkliətaɪd/

A nucleotide is the fundamental structural monomer unit of nucleic acids (DNA and RNA), consisting of three components: a five-carbon pentose sugar (deoxyribose in DNA, ribose in RNA), a nitrogenous base (adenine, guanine, cytosine, thymine in DNA; uracil replaces thymine in RNA), and one to three phosphate groups. Nucleotides also function as energy carriers (ATP, GTP) and signalling molecules (cAMP) independently of nucleic acid context. The sequencing of nucleotides in the human genome — comprising approximately 3.2 billion base pairs — is the basis of genomic medicine, which India is advancing through the IndiGen programme.

✍️ Usage in a UPSC answer

The IndiGen programme, launched by CSIR in 2019, sequenced the whole genomes of 1,008 Indians to map nucleotide-level variation across diverse ethnic populations, providing a reference dataset for pharmacogenomics and disease susceptibility research.

Synonyms

nucleic acid monomerbase unit (of DNA/RNA)mononucleotide

Antonyms

polynucleotide (multi-unit)nucleoside (dephosphorylated form — partial antonym by structure)

🌱 Word Family

nucleic (adjective), nucleoside (noun — nucleotide minus phosphate), polynucleotide (noun), dinucleotide (noun), nucleotidyl (adjective)

🔡 Root

Latin nucleus = kernel, nut (from nux = nut); -ote (chemical suffix); -ide (chemical bond suffix)

📜 Etymology

The term was constructed in the early 20th century from nucleo- (relating to the nucleus, from Latin nucleus, kernel) and -tide, a chemical suffix derived from Greek -tid used to denote structural components. The word 'nucleus' itself comes from Latin nux (nut), referring to the kernel of a nut as an analogy for the central body of a cell. The specific chemical meaning emerged as biochemists characterised the building blocks of nucleic acids in the 1920s–1950s.

🧠 Memory Hook

A nucleotide has three parts: Sugar + Phosphate + Base — remember 'SPB' or think of it as a 'seatbelt' (S=sugar, P=phosphate, B=base) that holds the DNA ladder together. The nucleo- prefix reminds you it lives in the nucleus, carrying the genetic code.

📝 Seen in UPSC Question Papers

Prelims 2021 — Biotechnology

Real UPSC previous-year questions whose text uses “Nucleotide” — proof this word earns its place on your list.

⚗️ General Science 📖 Seen in: Human Body Systems — Organ Systems, Ph...

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