This link takes you to a video that shows transport proteins moving along a cilium (It's called a flagellum at the site) in an alga called Chlamydamonas. Michael Behe talks about this system of proteins in his new book The Edge of Evolution, and it's astonishingly complex. Imagine small railroad cars carrying building supplies moving along a track that runs up and down an under-construction skyscraper.
The whole system would consist of hundreds of parts whose movements must be coordinated and timed with the availability and need for different supplies. The supplies would need to be loaded onto the cars and off-loaded at the site, and so on.
These proteins carry the materials necessary for the construction of a cilium and no one, evidently, has a clue as to how this system got set up or what keeps it organized, synchronized and functioning.
Behe describes the system in some detail, and it's fascinating reading. I'm about half-way through his book and if the second half is as interesting as the first it's going to be extremely hard to put down.RLC