Molecular motors are biological
molecular machines that are the essential agents of movement in living organisms. In general terms, a
motor may be defined as a device that consumes energy in one form and converts it into motion or
mechanical work; for example, many
protein-based molecular motors harness the chemical
free energy released by the
hydrolysis of
ATP in order to perform mechanical work. In terms of energetic efficiency, this type of motor can be superior to currently available man-made motors. One important difference between molecular motors and macroscopic motors is that molecular motors operate in the
thermal bath, an environment in which the
fluctuations due to
thermal noise are significant.