See DNA in three dimensions
Rotate and inspect a double-helix model — ball-and-stick to cartoon styles, colored by base or strand, exportable as PNG or PDB.
Open 3D viewer
3D DNA Structure Viewer
Input any DNA sequence — select A, B, or Z-DNA — visualize the 3D helix structure in real time.
Design validated primers for your target — free, no login, instant results.
Try the free primer design tool →Sequence Input
Understanding DNA Helix Structures
DNA exists in three major conformations depending on the environmental conditions. The 3D viewer above generates real coordinates using standard helix parameters from Saenger (1984), allowing you to visualize the differences between A-DNA, B-DNA, and Z-DNA directly in your browser. Preview what that sequence transcribes into with the free DNA to RNA converter, and build the oligos behind it with our primer design tool.
Design validated primers for your target — free, no login, instant results.
Try the free primer design tool →The double helix is held together by hydrogen bonds between complementary base pairs: A pairs with T through two hydrogen bonds, while G pairs with C through three. The aromatic bases stack vertically through pi-pi interactions, stabilizing the helix interior. The major groove (wider) is where most DNA-binding proteins read the sequence, while the minor groove (narrower) is targeted by small-molecule binders.