Reading a DNA Sequence
DNA is written in an alphabet of just four letters — A, T, G, and C — representing the nucleotides adenine, thymine, guanine, and cytosine. Everything from a protein's shape to a crop's nitrogen-use efficiency is ultimately encoded in long strings of these four characters.
The double helix, as text
The two strands of DNA are complementary: A always pairs with T, and G always pairs with C. Given one strand, you can always reconstruct the other — try editing the sequence below and hover any base to see its partner.
Reading frames
Ribosomes read DNA (via messenger RNA) three letters at a time. Each triplet —
a codon — specifies an amino acid. ATG is special: it's the start
codon that signals where translation begins, and TAA, TAG, TGA are
stop codons.
Shift the reading frame below and watch how completely the encoded protein changes — a single-base shift rewrites everything downstream.
Sequence composition
Not all sequences are alike. The proportion of G and C bases — the GC content — influences DNA stability and is one of the first things a bioinformatician checks when characterising a genome.
What's next
These widgets are plain React components embedded directly in this Markdown file — no change to the site's architecture. The same approach scales up to richer tools: a 3D protein-structure viewer (NGL Viewer), a genome-track browser (igv.js), or interactive phylogenetic trees, all of which can drop straight into future tutorials.