Biology and Physical Factors #5: Brownian Motion
At the molecular level, nothing is ever still. Thus, every picture of DNA or proteins is fundamentally flawed – everything is a blur of motion. Yes, the famous Brownian motion at work. Brown had shown this was not a concept limited to living things only; it was something rooted in physics. It is totally random. Mathematical analysis can predict, on average , how far a particle would move from its starting point if the direction of each step is random. Hence the term “predictable randomness”. Also, the larger a molecule, the less it moves. Ok, how is any of this relevant to biology and life? Raghuveer Parthasarathy explains in So Simple a Beginning : “(Brownian motion) solves a nagging problem with our discussion of self-assembly.” In earlier blogs, we saw proteins can arrange themselves into patterns. But Lego blocks don’t do that. What’s the difference? Brownian motion gives the answer – the size (Lego blocks are too large to undergo Brownian motion). “The recipe for self-assem...