DNA Double Helix (2D) — Ladder Diagram & Base Pairing

Helix

Rotation speed 1.0

Base pairing

Adenine (A) — pairs with T

Thymine (T) — pairs with A

Guanine (G) — pairs with C

Cytosine (C) — pairs with G

Live Readouts

Base pairs shown

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GC content

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How it works

This is a flattened, top-view-free ladder diagram of the same double helix the 3D version renders in space: two antiparallel sugar-phosphate backbones, drawn here as two sinusoids 180° out of phase, x(y) = cx + R·cos(θ) and cx + R·cos(θ+π), where θ advances with height and with time to fake the helix's rotation about its own axis. The near/far strand and rungs are shaded and thinned by sin(θ) so the parts curling toward the viewer read as closer.

Unlike a purely decorative helix, the rungs here are drawn from a real generated base sequence rather than a coin flip per rung: each position on one strand gets a random base (A, T, G or C), and the opposite strand's base is derived from Watson–Crick pairing rules — A always opposite T, G always opposite C — so every rung splits into two correctly complementary colored halves, exactly as real DNA base pairing works.

x1(y) = cx + R·cos(θ(y,t))
x2(y) = cx + R·cos(θ(y,t) + π)
pair(A) = T, pair(T) = A, pair(G) = C, pair(C) = G

Drag the rotation-speed slider or toggle auto-rotate / base pulsing