Short answer is that the ribbon representation is a visual simplification based on known structures -- they are actually composed of atoms.
They certainly do "thrash around", but that thrashing is constrained by the bonds that are formed, which greatly limits the degrees of freedom. Here's a short video of a simulation to demonstrate:
They certainly do "thrash around", but that thrashing is constrained by the bonds that are formed, which greatly limits the degrees of freedom. Here's a short video of a simulation to demonstrate:
https://www.youtube.com/watch?v=fggqPtaZj8g