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.

1. Which aspects of  the the motion of proteins in cells does the second video capture more realistically?  
2. Are any aspects of biological phenomena (or physical processes) captured better in the first video?  If so why, if not why not?  
3. Discuss which of the videos you prefer and why. Which do you think is better to show to an introductory biology student? Explain why you think so. 

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