There are 2 videos to see.
Video 1 : https://www.youtube.com/watch?feature=player_embedded&v=wJyUtbn0O5Y shows actin polymerizing. The cell seems very empty, and somehow the actin molecules seem to know to run right where they are needed. Really, a cell is crowded with water and proteins and everything is "jiggling" due to being inside a fluid of jiggling water molecules thermal motion.
The actual motion looks more like video 2:
https://www.youtube.com/watch?feature=player_embedded&v=uHeTQLNFTgU
Each video has its advantages. The first is clearer, the second more realistic.
QUESTIONS:
(a) Which aspects of the motion of proteins in cells does the second video capture more realistically?
(b) Are any aspects of biological phenomena (or physical processes) captured better in the first video? If so why, if not why not?