Basically, diffusion means we still have a movement down the electrochemical gradient but now we actually need a protein to move that molecule across. So basically, in this case, as in this case, we have the movement of our molecule down the electrochemical gradient. In this case, we don't use any type of protein and we don't use any energy. In this case, we don't use energy, but we do need our protein because as in this case, we use sugar. Sugar is a large molecule. It's also very polar.