Physicists prove energy input predicts molecular behavior
The world within a cell is a chaotic space, where the quantity and movement of molecules and proteins are in constant flux. Trying to predict how widely a protein or process may fluctuate is essential to knowing how well a cell is performing. But such predictions are hard to pin down in a cell’s open system, where everything can look hopelessly random. Now physicists at MIT have proved that at least one factor can set a limit, or bound, on a given protein or process’ fluctuations: energy. Given the amount of energy that a cell is spending, or dissipating, the fluctuations in a particular protein’s quantity, for example, must be within a specific range; fluctuations outside this range would be deemed impossible, according to the laws of thermodynamics. This idea also works in the opposite direction: Given a range of fluctuations in, say, the rate of a motor protein’s rotation, the researchers...