AI Tutor
If you stretched out all the DNA inside a single microscopic human cell, it would measure nearly six feet long.
That microscopic strand contains the entire instruction manual for life, stored in a family of biomolecules called nucleic acids.
What simple chemical building blocks can store such a massive amount of information?

The Anatomy of a Nucleotide

Every nucleic acid is a long polymer made of repeating monomer subunits called nucleotides.
Each nucleotide is built from three distinct parts: a phosphate group, a five-carbon sugar, and a nitrogenous base.
Nucleotides join together when the phosphate of one nucleotide connects covalently to the sugar of another, creating a sturdy sugar-phosphate backbone.
How do these chains fold and pair up to store information securely for decades?

DNA: The Master Blueprint

Deoxyribonucleic acid (DNA) stores the permanent genetic code inside cells, arranged as two intertwined strands called a double helix.
In 1953, James Watson and Francis Crick determined this structure, relying heavily on Rosalind Franklin's groundbreaking X-ray diffraction images.
The two strands run in opposite directions—a property known as being antiparallel—with one strand running 5′→3′5' \rightarrow 3' and the other running 3′→5′3' \rightarrow 5'.