A nucleotide is made of three main parts: a nitrogenous base, a five‑carbon sugar, and one or more phosphate groups. These three components together form the basic building block of DNA and RNA.

Core components

  • Nitrogenous base : A ring-shaped molecule containing nitrogen; in DNA these are adenine, guanine, cytosine, and thymine, while RNA has uracil instead of thymine. The specific order of these bases encodes genetic information.
  • Pentose sugar: A five‑carbon sugar, either ribose in RNA or deoxyribose in DNA. The sugar type helps distinguish DNA from RNA and affects overall molecule stability.
  • Phosphate group: One to three phosphate units attached to the sugar that give nucleotides their negative charge and link them into long chains. These phosphate bonds also store energy in molecules like ATP.

How they fit together

  • The sugar and base together are called a nucleoside; adding the phosphate makes it a full nucleotide.
  • Nucleotides join when the phosphate of one bonds to the sugar of the next, creating the sugar‑phosphate backbone of DNA and RNA strands.

Quick forum-style recap

A nucleotide = base + sugar + phosphate. The base carries the genetic “letter,” the sugar holds the structure, and the phosphate links everything into a chain.

TL;DR: What makes up a nucleotide? One nitrogenous base, one five‑carbon sugar (ribose or deoxyribose), and one or more phosphate groups.

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