4.3.3.P7
The processes happening inside a cell are often complex and hard to make sense of. Some groups have made extensively developed animations in order to help students (and scientists!) visualize what's going on. Here's one. Click on the image to see the animation.
The animation is very well done. But some things seem strange. The frame above shows actin polymerizing. The cell seems very empty, and somehow the actin molecules seem to know to run right where they are needed, like children being called in for play for dinner. How do they know to do that?
Well, the answer is, of course, they don't. 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 the following video.
Each video has its advantages. The first is clearer, the second more realistic.
Note: This is an essay question. Your answer will be judged not solely on its correctness, but for its depth, coherence, and clarity.
Source: Carl Zimmer. http://ht.ly/vNjjq
Joe Redish and Wolfgang Losert 4/16/14