The smallest unit of DNA is called a nucleotide.
A nucleotide is the fundamental building block of DNA (deoxyribonucleic acid) and RNA (ribonucleic acid). Each nucleotide consists of three components:
- A nucleobase (also called a nitrogenous base): There are four types of nucleobases in DNA: adenine (A), guanine (G), cytosine (C), and thymine (T).
- A five-carbon sugar (deoxyribose in DNA): This sugar provides the structural backbone for the nucleotide.
- One or more phosphate groups: These phosphate groups link nucleotides together to form a DNA strand.
Nucleotides are linked together through phosphodiester bonds to create long chains of DNA. These chains then wind around each other to form the well-known double helix structure of DNA. The sequence of nucleotides carries the genetic information that determines the characteristics of an organism.
In simpler terms, think of DNA like a necklace. The entire necklace is DNA, and each individual bead on the necklace is a nucleotide. The nucleotide is the smallest repeating unit that makes up the larger DNA molecule.
