Wednesday, August 18, 2010

Random Walks - some thoughts.

Having failed to get to sleep tonight, I decided just to think about this chapter, and the applications of random walks, and if I could think of any interesting phenomena to mention. And then this first one came to me.
Say you have two different chemicals, which react with each other, and the volumes of each are such that they will both completely react. When you mix these together, I want to ask the question, how long will it really take for these two to mix together? Because if you think about it, we associate reaction completion when we can no longer see, hear, smell any changes going on, when our reaction measuring equipment no longer detects any significant readings. BUT, if our molecules are undergoing brownian motion, just how long could at least one molecule of each chemical play cat and mouse with each other?
Second thought of the night.
I was reading over the polymer section, and I remember having learnt about the radius of gyration last semester in a physical chem course, when we were studying polymers that had adsorbed to a surface. However, though we also learnt brownian motion, it wasn't a concept that they explicitly linked to the radius of gyration phenomena (they had been linking it more to the physical and chemical properties). Now having read the chapter though, it actually starts to make a bit more sense how it works, and also how i can extend that knowledge also to say the folding of a protein.
Third and final thought.
Having just written that second though, a third though came to me, which is that Brownian Motion can actually have order to it, such as when a protein is folding. When a protein folds, obviously all the atoms making it up are still experiencing Brownian type motions, but due to the specific situation it is, that motion actually becomes controlled, like if you will, a dog on a leash. Marvellous what our universe holds in its mysteries for us of what it can achieve.

1 comment:

  1. Good point re: protein folding. Remember Levinthals paradox, and its apparent resolution: brownian motion on a funnelled surface.

    Ken Dill wrote a nice 1997 perspective in Nature Structural Biology on the issue (with lots of nice illustrations):