"Quantum Biology"

 

ABSTRACT: 

 

Biology has had over three billion years to explore mechanism in the physical world. The role of quantum mechanics in governing the properties of electrons in biological molecules or in specific biological processes such as absorption of photons in the eye is not controversial. Recently, however, the notion that quantum effects such as coherence, interference, tunneling, and possibly entanglement may play a role in some biological processes has re-emerged. I will review experiments demonstrating quantum coherence in the early steps of photosynthesis, and discuss the question as to whether these observations have biological significance or are an accidental side effect of the structure of photosynthetic molecules. Almost in reverse to the situation in photosynthesis, two ideas suggest a clear biological role of quantum mechanics in sensory processes, but remain unproven. I will briefly review the controversial idea that the sense of smell exploits phonon-assisted tunneling and supporting evidence and then turn to the magnetic sense of animals. Here, the radical-pair mechanism explains how the coherent evolution of a pair of electron spins can mediate sensitivity to external magnetic fields. I will review the current state of evidence supporting this idea, inferences drawn from experimental results, as well as ongoing efforts to elucidate the mechanism of magnetic sensing.