Quantum Biology

Biology at the cellular level is just complex organic chemistry and chemistry is about the interaction of atoms ,which are governed by the law of physics. However when studying cellular processes; simply using the classical understanding of physics proves inefficient  in accurately explaining the nature of several biological processes we observe . Particularly the  almost perfect efficiency of photosynthetic organisms in converting solar energy to usable chemical energy and the detection of the geomagnetic field by migratory birds .  Hence I believe that it is very likely that  many organisms depend on mechanisms governed by the laws of quantum mechanics and use many different quantum phenomenon to their advantage and for their survival .

I would like to preface this essay by briefly explaining what is quantum mechanics   Quantum mechanics is the study of atoms and  subatomic particles which are the smallest energy levels in the universe .Hisenberg’s uncertainty principle asserts a fundamental limit to the precision of measuring both the  position and momentum of a particle at a given time. Hence every particle is best described as having a Wavefunction , which gives us a probability curve predicting the position of a particle in space-time .This is why every particle in the universe has a wave like nature . This phenomenon is very small and insignificant at macroscopic scales and Only in the quantum realm does this become significant .Because such small scales are alien to us , the interpretation of the mathematics (the language of the universe) of quantum physics appears to be very strange and counter intuitive at best .but reality by definition is what keeps going on whether someone believes in it or not !

 When the wavefunction of a particle remains unchanged even when a specific transformation to the system is applied , this is called 'quantum coherence’. This phenomenon of quantum coherence then gives rise to many different quantum effects such as quantum super positioning , entanglement and quantum tunnelling . In this essay I will present evidence and describe how organisms  function using some of these quantum phenomenon.

Quantum super-positioning is one of the fundamental principles of quantum mechanics . Since the mathematics of quantum physics describe the position of a particle as a probability function , it turns out that it is possible for a particle it to simultaneously occupy multiple separate positions in space at once but for very brief periods of time . This weird phenomenon is used by photosynthetic organisms to deliver the energy of a photon to the photosynthetic reaction centres in the chloroplasts .when a photon lands on the surface of a leaf , the energy of the photon has to be transferred  to the photosynthetic reaction centre but it has to go through several bridges made up of complicated arrays of chlorophyll molecules to get to its desired destination . This process needs to occur at a rate faster than a nanosecond , or else the energy of the photon is absorbed and wasted in the bridging area .The only possible way this energy transfer can occur as efficiently as it occurs in organisms is if the energy of a photon , travels through all possible paths at the same time .

This was first demonstrated by scientists when an experiment [1] observing photosynthesis in bacteriochlorophyll complex showed evidence of electronic quantum coherence . Two-dimensional spectroscopy based on four-wave mixing demonstrated that quantum coherence made the energy transfer process possible . The spectroscopic signature exhibited clear evidence of quantum ‘beating’ at 77k .

Another study[2] showed that photosynthetic proteins in purple bacteria oscillate at fixed synchronized frequencies essentially forming a Super-molecule . Calculating and treating the PSII reaction centre as a supermolecular complex allow energy and electron transfer reactions to be described in a unified way . This also helped explains the very high (almost 100%) efficiency of photosynthetic organisms in converting solar energy into chemical energy , the process which is directly or indirectly responsible for most life on the planet .the most exciting thing about science is that we know a lot but do not know a lot more . More research into the mechanisms of photosynthesis could further our understanding in energy transfer and could lead to much better solar panel technology helping in solving the global energy crisis .

It was discovered a long time ago that animals can detect the geomagnetic field and use it for navigation, especially during migration . However the true mechanism of how this works was never understood . In the absence of a magnet detection organ in animals , scientists had to invoke quantum entanglement to explain this process .

 Quantum entanglement is just another affect of quantum coherence .laws of quantum mechanics dictate that the fate of two quantumly interacting particles is always intertwined .that is , Particles in a combined quantum state (having the same energy) even when separated by a distance somehow can affect each other instantaneously . For example , 2 electrons in an electron pair have opposite spins (explained by pauli's exclusion principle ) described as up or down spin . In reality both electrons have a probability of having either up or down spin which can be calculated mathematically called ‘superpositioning of spin’ .This can be interpreted as if both electrons have both up and down spin at the same time .But when we isolate an electron from the pair and measure it’s spin , we do get a definitive measurement i.e. Either spin up or spin down . It turns out that the act of measuring the spin one electron of the pair somehow gives the other electron a definitive spin as well , that is opposite to the spin measured on the first electron no matter how far away it is. This transfer of information occurs literally instantaneously , faster than the speed of light , breaking the cosmic speed limit which proves that there are no new undiscovered particles involved . Many experiments were conducted that further shed light on how this phenomenon could be used by birds to detect the geomagnetic field and use it for migration .

The first step was finding out the organ responsible for detection of magnetic fields .An experimental study [3] By behavioural evidence showed that when eyes of insects and birds were covered up , they were unable to sense the geomagnetic field isolating eyes as the organ responsible of detection of magnetic fields .Furthermore genetic and behavioural techniques were used to confirm the hypothesis that cryptochrome 2 protein was responsible for magnetic field detections . When cry2 (the gene responsible for cryptochrome production) levels were reduced in cockroaches by injections of double-stranded (ds) cry2 rna (rnai), they showed arrhythmic circadian rhythms and were again unable to navigate using the geomagnetic field . A radical pair mechanism using quantum entanglement in the protein cryptochrome was proposed.

This proposal hypothesised that when photons enter a bird’s eye they sometimes knock an electrons out of the molecules of the protein cryptochrome resulting in radical pairs . An electron that gets separated from the molecule aligns its spin according to the Earth’s magnetic field . As a result the other electron which is still in the cryptochrome protein molecule because of quantum entanglement adapts the opposite spin  which the bird can sense and ultimately sense the geomagnetic field.   

A study in 1994 by harkins tt1, grissom cb.[4]

 Showed that the kinetic parameter vmax/km (where km is the michaelis constant) for the coenzyme b12-dependent enzyme ethanolamine ammonia lyase fluctuated , ie. Decreased 25 percent by a static magnetic field near 0.1 tesla (1000 gauss) with unlabelled ethanolamine and decreased 60 percent near 0.15 tesla with perdeuterated ethanolamine . Showed evidence that the radical pair method of magnetic field detection could interact with biological life forms and result in detection of magnetic fields by animals .

Due to these evidences , in the past few years several new hypotheses have emerged that invoke quantum mechanics to explain biological processes . These include , using quantum tunnelling ( where particles pass through barriers due to their probabilistic wave like nature ) to explain the sense of smell in animals , quantum coherence to further increase our knowledge of cancer causing DNA mutations  and even decoding the hard problem of consciousness based on quantum entanglement .

Initial sceptics of quantum phenomenon in biology pointed out that quantum effects that we observe are only viable and observable in isolated systems at extremely low temperatures of just a few kelvin whereas cells are warm , wet and congested environment inhospitable to these delicate processes . Another point of investigation and debate was that quantum phenomenon are observable only for very short periods of time and it was said that organisms could not hence depend on quantum coherence . However many recent experiments and studies show promising evidence in the favour of quantum biology .

Researchers in the university of California [5] studied quantum coherence in photosynthesis as 77 k, 125 k, 150 k, and 277 k and showed quantum beating signals among all four temperatures while showing shorter quantum beat lifetimes at higher temperatures . Decoherence occurred in 300 fs at 277k which is four times faster than at 77k . For photosynthesis to be dependent on quantum mechanics  all quantum coherences should have a chance to complete at least one oscillatory cycle in their wave function . 300 fs allow for 2 complete cycles to occur , proving that quantum coherence in photosynthetic molecules can occur even at room temperatures .

A 2012 study from Singapore [6] calculated the life time of the functional window of quantum entanglement in bird retina when exposed to rf (electromagnetic fields) of brf = 470nt ,brf = 150nt and brf = 47nt (0.1% strength of the local geomagnetic field) the experiment showed that the  average life time of the radical pair taking part in the avian magnetoreception was around a few micro seconds , which is enough time for birds to sense its affect and use it effectively for navigation .

Quantum mechanics is very strange and bizarre in explaining the nature of reality but it gives predictions accurate to multiple decimal places hence is our best theory so far . The universe is under no obligation to make sense to us and hence we should let go of our intuitions and notions and continue probing nature with the methods and tools of science .

The field of quantum biology is fairly new ,however  these new found evidences have opened up a new room for scientific discoveries and even technological advancements . Maybe nature does know a few tricks that physicists do not !  Needless to say the future of this new emerging field of quantum biology is bright and I believe will substantially increase our understanding of  nature and the nature of reality itself . 

 [references] 

[1]  [ evidence for wavelike energy transfer through quantum coherence in photosynthetic systems gregory s. Engel1,2, tessa r. Calhoun1,2, elizabeth l. Read1,2, tae-kyu ahn1,2, toma´ˇs mancˇal1,2{, yuan-chung cheng1,2, robert e. Blankenship3,4 & graham r. Fleming1,2 vol 446| 12 april 2007| doi:10.1038/nature05678  ]

[2] [quantum photosynthesis. By: choi, charles q., scientific american, 00368733, aug2007, vol. 297, issue 2]

[3] [sci u s a. 2016 feb 9; 113(6): 1660–1665.

Published online 2016 jan 25. Doi:  10.1073/pnas.1518622113

Cryptochrome 2 mediates directional magnetoreception in cockroaches

Olga bazalova,a,b,1 marketa kvicalova,c,1 tereza valkova,c pavel slaby,c premysl bartos,c radek netusil,c katerina tomanova,c peter braeunig,d how-jing lee,e ivo sauman,a,b milena damulewicz,a jan provaznik,a,b richard pokorny,f,2 david dolezel,a,b,2 and martin vachac,2]

[4] [science. 1994 feb 18;263(5149):958-60.

Magnetic field effects on b12 ethanolamine ammonia lyase: evidence for a radical mechanism]

[5] [long-lived quantum coherence in photosynthetic complexes at physiological temperature - gitt panitchayangkoona, dugan hayesa, kelly a. Fransteda, justin r. Carama, elad harela, jianzhong wenb, robert e. Blankenshipb, and gregory s. Engela,1 graham r. Fleming, university of california, berkeley, ca, may 3, 2010 ]

[6] [ quantum coherence and sensitivity of avian magnetoreception

Jayendra n. Bandyopadhyay,1, ∗ tomasz paterek,1 and dagomir kaszlikowski1, 2 ]