Generalities Regarding Machines and Motors

Molecules possessing shapes that can be modified from the outside by sending some form of signal to the system are, of course, numerous. However, molecular machines tends to refer to large-amplitude motions resulting in real translocation of some parts of the compound, reversibility being an essential feature of the system. 

In order for an object to be regarded as a motor, several basic requirements have to be fulfilled. Even without trying to apply a strict thermodynamic definition, the system will have to convert a certain type of energy into another form of energy, while undergoing some kind of continuous motion. 

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