Sanger Sequencing: Chain Termination & Capillary Electrophoresis

This simulator models the classic dideoxy chain-termination method that first made genome sequencing possible. A random DNA template is copied into fragments that end at every possible length, each one dye-labeled by the base that stopped it. Those fragments are then injected into a 3D capillary and pulled by an electric field through a sieving polymer, where mobility scales inversely with fragment length — short fragments race ahead, long ones lag behind. A laser detector at the far end reads each fragment's color as it arrives, shortest first, live-reconstructing the sequence exactly the way a real automated sequencer's electropherogram does. Template length and field strength are both adjustable, exposing the real speed-versus-resolution trade-off that governs actual capillary sequencing runs.