DNA Replication (2D)

This top-down companion to the 3D DNA replication simulator lays the same molecular machinery flat: a replication fork advances as helicase unwinds the double helix, DNA polymerase rides the fork to synthesize the leading strand in one continuous piece, and primase repeatedly lays short primers on the lagging strand so its own polymerase can fill in the discontinuous Okazaki fragments that ligase then seals into a single backbone. Adjusting the fork speed shows how every part of the machinery — helicase, both polymerases, primase and ligase — stays locked to the same rate, because none of them can outrun the strand the fork is exposing.