Reckoning / Code of life
Room · wave 4
Code of life
DNA is a code written in four letters, held in two strands that wind round each other. This room covers the letters themselves, the shorthand biologists use when a letter is uncertain, the shapes the double helix can take, and the topology of DNA that is closed into a loop.
Bases and pairing
The four bases drawn atom by atom, the nucleotide, and why A pairs with T and G with C.
The IUPAC letters
R, Y, N and the rest: a decoder that expands, complements and searches sequences.
The double helix
A, B and Z DNA in 3D, with their dimensions.
Supercoiling
Topology lens: linking number = twist + writhe, computed on a ribbon you can coil.