The Cost of Sending a Bit Across a Living Cell

F or a cell to stay alive, its different parts must be able to exchange signals. Transmitting signals consumes energy, of which every cell has a limited supply. Now Samuel Bryant and Benjamin Machta, two physicists at Yale University, have derived the minimum energy that a cell needs to transmit an internal signal using electrical current, molecular diffusion, or sound waves [1]. Their calculations show that the most efficient signaling mechanism depends on several factors, including the distance that the signal needs to travel. This finding matches everyday human experiences of