Similar to computing on chips, the biochemical networks behind cellular computations are also constrained by energetic considerations, write Boston University's Pankaj Mehta and Princeton University's David Schwab in a paper posted online at arXiv. Mehta and Schwab examined a simple two-component cellular network "that encodes information about ligand concentration in the steady-state concentration of the activated form of a downstream protein" — which they note is common in bacteria — and calculated its energetic costs. "[Our calculations] suggest a fundamental relationship between the efficiency of cellular computing and the energy consumption," Mehta and Schwab write.
"These guys actually derive a mathematical expression that gives this biochemical circuit's power consumption," KFC adds at the Physics arXiv Blog. "The expression shows that learning about the environment always requires the network to use up energy."