This Article is a Compilation of the Virtual Google Meet discussion that happened on 26th July 2020 in the Scientific Community Discussion Forum: Sci-Chat. It cannot be very perfect as it is opinionated.
(Image Credits: https://www.rsb.org.uk/biologist/158-biologist/features/541-making-the-quantum-leap)
Introduction:
Quantum Biology could actually be surrounding us everywhere. It’s proposed to be what gives us eyesight. It is what runs photosynthesis in plants. It’s supposed to be what tells birds what direction to fly towards. It is what determines the states of particles entangled at the quantum level. DNA mutation can also be attributed to Quantum Biology. It is supposed to be based on hypotheses of speeds faster than that of light. Quantum Biology is basically the marriage of Biology with Quantum Physics. The principles of energy absorption, excitement, electron spin, etc. that we learn under the umbrella of Biophysics can owe a lot of its substance to Quantum Biology. Biomolecular mechanisms can be observed in a new light from Quantum Mechanical aspects.
History:
Quantum biology is defined as the study of applications of quantum mechanics and theoretical chemistry to biological objects and problems. The first-time listener might think this term “Quantum Biology” as a trendy brand new term and field in Science. But it is rather old, the science of Quantum Biology first came into existence on 15th August 1932 when Danish physicist Niels Bohr gave a talk at International Congress on Light Therapy in Copenhagen and the title for Bohr’s talk was Light and Life, where he hinted for thinking of new perspective or rather to say the application of Quantum Mechanics in Biology or in a broader perspective in Life. In his talk, Bohr quoted “whether some fundamental traits are still missing in the analysis of natural phenomena before we reach an understanding of life on the basis of physical experience” Bohr left this statement quite unclear which was a kind of puzzle in its own way, but in the audience this very statement influenced a young attendee who was back than German theoretical physicist, but soon after his returning from Copenhagen to Berlin, he decided to find the kind of missing trait which was mentioned by Bohr by studying physical and chemical nature in genetics, as this was what he elucidated from Bohr’s talk, but for him it didn’t mean that physics might help to explain genetics but rather study of genetics might unravel some new principle of physics, at same time nothing was known about the molecular origin of genetics, people didn’t knew about gene and its association with DNA, but they do started understanding that how genes evolved in population according to Darwinian principle. In 1937, he went to America and started working on the genetics of Bacterial Viruses since they were very simple forms of life, and his work earned him Nobel Prize in Medicine and Physiology in 1969, he was none other than Max Delbrück.
Max Delbrück established the idea of genetics as the science of information in Biology, he also ignited the interest of other physicists in Biology, and one of them was Erwin Schrödinger, who later went to write a famous book “What is Life” published in 1944, in which he has advocated the same thought of quantum physics application in biology which later influenced many other leading chemists and physicist like Francis Crick. But there was one more pioneer who supported the same school of thought which Bohr was referring to, even before Erwin Schrödinger and Max Delbrück, and he was Pascual Jordan, a German theoretical and mathematical physicist who made significant contributions to quantum mechanics and quantum field theory and was an author on the classic papers on quantum mechanics along with Max Born and Werner Heisenberg. But Jordan is lesser-known than Max Born and Werner Heisenberg but he certainly was one of the quantum pioneer of1920s. Jordan in a sense can be considered as founder Quantum Biology field, he published a book a year before Erwin Schrödinger’s, which was entitled as “Physics and the Secret of Organic Life” and in the same book, he asked the question “Sind die Gesetze der Atomphysik und Quantenphysikfür die Lebensvorgänge von wesentlicherBedeutung?” which meant that ‘Are the laws of atomic and quantum physics of essential importance for life?’. He was looking for the rules from the quantum world like indeterminism, complementarity, the idea that he had developed by studying under Bohr, he wanted to check whether this idea can be applied to understand the vital role of life, he even published the very first paper titled as “Quantenmechanik und die Grundprobleme der Biologie und Psychologie” (Quantum mechanics and the basic problems of biology and psychology) in 1932 and later “QuantenphysikalischeBemerkungenzuBiologie and Psychologie” (Quantum physics remarks on biology and psychology) in 1934. In fact, Jordan had been thinking all this for about an over a decade but only in the late1930s, he started using the term “Quantenbiologie” (Quantum Biology). But Pascual Jordan’s political sympathies with Nazi Germany ruined his image after the war and this is why the field of Quantum Biology did not get the necessary acceptance at that time. However, there were others who still believed in the concept of using Quantum Physics to understand Life.
So in the early 1930s, the concept of Quantum Biology migrated from mainland Europe to England. In 1932, a group was set up in The University of Cambridge and it was named as Theoretical Biology Club, and some of the greatest thinkers of that time were in that group even people like evolutionary biologist J.B.S Haldane, biochemist Frederick Gowland Hopkins, who was awarded the Nobel Prize in Physiology or Medicine in 1929, mathematician Dorothy Wrinch, who attempted to deduce protein structure using mathematical principles and developmental biologist Conrad Waddington and many other leading physicists, mathematician, and biologist. This club essentially advocated a view, which was called as organisms, it was a philosophical position which rejected to understand life by the mechanistic view and also by the vitalistic view. Whereas they believed in philosophy which states that the universe and its various parts including human societies are to be considered alive and naturally ordered, much like a living organism and this way of thinking was leading toward the same field unknowingly which scientist like Niels Bohr, Pascual Jordan, Max Delbrück, and Erwin Schrödinger were advocating. During the 1940s to 1970s both Quantum Physics and Molecular Biology, Genetics were developing successfully parallel to each other at the same time. Till than physicists were quite busy and don’t want to put their hands in the messy world of biology just like biologists don’t want to apply physics and hard mathematics to understand life. Till the 1990s very little was done in quantum biology it was more considered as wacky science or more of pseudoscience, but on another hand some work was still done to support the relevance of quantum phenomena in biology. By using advanced experimental techniques such as fast pulsed laser, 2D Spectroscopy to study biomolecules began showing quantum effects like long-lived coherence, interference pattern, and many more.
In the later 1990s, two of the professors from University Of Surrey, nuclear physicist Jim-Al-Khalili and molecular biologist Johnjoe MacFadden jointly published a paper entitled as “A quantum mechanical model of adaptive mutation” in 1998 were they applied the concept of quantum superposition to give a new approach in understanding adaptive mutation in bacteria Escherichia coli. Later a group in University of California, Berkeley leaded by Greg Engel used 2D Fourier Transform Electron Spectroscopy and suggested quantum coherence phenomena in plants during the photosynthesis process and published finding in 2007, much more research was conducted by applying the concept of quantum physics in biology to understand many concepts like Radical Pair Mechanism in Migratory Birds, Hydrogen or Proton Tunnelling in Enzymes, Quantum Coherence in Photosynthesis and many more…
Quantum Entanglement:
“Entangled pairs'' are the particles that are the products of interaction and they are called entangled due to their “Quantum States” being interdependent on each other and this is called Quantum Entanglement. Let’s take, for example, Spin states of an entangled pair of electrons. Spin is an intricate value that is present in all particles, but a particle only gains a fixed spin value (+1/2 or -1/2), when measured. In the case of Entangled pairs of electrons, the spin state remains ambiguous for either particle until one of the particles' spin is measured. But once the spin of one electron is measured, the spin of the other electron will always be the opposite. This stands true with the properties of entangled pairs measured even when they are separated over long distances. This means that the act of measurement of spin has influenced the spin state of entangled pairs.
Now that we have established Quantum entanglement, what does it have to do with Biology? Well, there is a phenomenon known as “Magnetoreception” which is the ability to sense magnetic fields and is present in many species ranging from bacteria to birds, reptiles, and even some mammals.
One of the mechanisms through which some birds detect this is mediated by molecules called “Cryptochromes”. Cryptochromes are light-sensitive proteins that are present in the eyes of birds, and when exposed to a certain wavelength of light, get excited and produce an “Entangled pair” of radicals. These radicals can be in one of either spin states - singlet or triplet. In a singlet state, the spin of the excited particles will be antiparallel (opposite); but in the case of triplet state, the particles, in an excited state, have parallel (same direction) spin.
“Entangled pair” of radicals. These radicals can be in one of either spin states - singlet or triplet. In a singlet state, the spin of the excited particles will be antiparallel (opposite); but in the case of triplet state, the particles, in the excited state, have parallel (same direction) spin.
The singlet or triplet states are interconvertible and their conversion is influenced by an external magnetic field. Therefore, the ratio of the products formed and the interconversion depends on the orientation of an external magnetic field. Thus, by measuring the ratio of the products formed, this radical-pair mechanism acts as a chemical/molecular compass in birds and it helps in the navigation by providing directional information.
Quantum Coherence & Megnatosomes:
The phenomenon of Photosynthesis is long-studied in Biology and a staple of those who major in Botany, Environmental Science, or other subjects. It can be astonishing to think of how efficient a plant system is when one realizes that it can convert almost all of its absorbed light energy into the chemical energy required for photosynthesis. Quantum Biology attempts to explain this efficiency in energy transfer as the perfectly well-guided transfer of a photon, or light particle, to the Light-Harvesting Complex of a leaf. The LHC is composed of accessory pigments like carotene, xanthophyll, etc. which are found in variable amounts in varying species of plants, and at its center lies the main Reaction Centre that harvests a photon’s energy to split water into oxygen and hydrogen - the starting point of photosynthesis. Alas, a loss in energy is bound to be when energy transfer takes place from one form to another, in accordance with the laws of thermodynamics. Indeed, in a plant, when photons are harvested, they are also sent to the Reaction Centre as efficiently as possible, but understanding this through classical Biology or Physics proves lacking.
However, when Quantum Biology is applied, one can build an interesting hypothesis for this. Let us assume that a molecule has multiple pathways to go from one energy state to another. Out of these pathways, the one which will result in the least work done by it, i.e., the one with the least energy barrier, will be the path it takes. One can compare this to an enzymatic reaction where the enzyme-catalyzed pathway will be the one taken instead of one where the enzyme is not involved. This is applicable to several daily phenomena as well, and also not, since we’re talking about objects in the micro-scale. Similarly, a photon has to navigate through the accessory pigments to the Reaction Centre and finally cause the splitting of water to form electrons to be taken up by the Electron Acceptor. This is easier understood if we consider a Quantum mechanics approach, which shows the easiest or least energy pathway the photon can take to reach the Reaction Centre. Thus, the plant loses the least amount of energy since the photon takes the shortest and least energy-consuming pathway to reach its destination – the Reaction Centre.
When talking about the Cryptophores, or magnetic navigation organs in the eyes of birds that are explainable by the Radical Pair mechanism of Quantum Biology, it was speculated whether magnetotactic bacteria, a special kind of bacteria that use organelles consisting of magnetic compounds to navigate, also rely on this principle. A probable analogy to the quorum sensing bacteria use to build on its colonies or biofilms was also made. However, Magnetosomes, as those organelles are called, and quorum sensing pheromones seem to work on vastly different principles. It may be a basis for non-quorum sensing reliant communication among bacteria, however, and something that requires reading and research.
Quantum Tunneling:
Quantum tunneling is the phenomenon related to quantum mechanics in which the subatomic particles have the probability to disappear from one side of the potential barrier and appears on the other side. In Simpler, way the probability of that particle to appear on the other side is non-zero.
Quantum tunneling plays a key role in the field of biology referred to as Quantum Biology. In quantum biology, the tunneling of electron and proton both are important as electron tunneling is a key factor in many biochemical redox reactions (photosynthesis, cellular respiration) and also enzymatic catalysis while on the other hand proton tunneling has a key role in the spontaneous mutation of DNA.
Many studies have focused on the hydrogen transfer itself without considering whether tunneling is the cause. Some have claimed that tunneling in DNA is either not possible or so unlikely as to be statistically negligible. Others claim it is a reasonable possibility. In the case of DNA base pairs, Scientists declared that once a DNA replication event had occurred, the protons in the connecting hydrogen bonds would be in one of several quantum states, some or all of which could lead to potential tunneling events, affecting any future replication events.
From the aspect of quantum biology proton tunneling is defined, as a spontaneous mutation of DNA starts when normal DNA replication takes place after a particularly significant proton has defied the odds in quantum tunneling. The hydrogen bond holds the bases of DNA together. There are 3- hydrogen bonds between G-C and 2 Hydrogen bonds between A-T. There exists a double-well potential along a hydrogen bond separated by a potential energy barrier. It is believed that the double-well potential is asymmetric with one well deeper than the other so the proton normally rests in the deeper well and the proton must have tunneled into the shallower of the two potential wells for a mutation to occur. This Shifting of the proton from its regular position is called a tautomeric transition. Now the DNA is more prone to mutation. Because if DNA replication takes place in this state, the base-pairing rule for DNA will be distorted and can cause a mutation.
The likelihood of quantum tunneling occurring within DNA and the question of whether this is a significant contributor to spontaneous point mutations has been the subject of much research over the past few decades. It is now known that the external environment, such as the presence of water molecules, also plays a role in the stability and structure of DNA. The question of interest is the extent to which the environment might play a role in promoting or inhibiting proton transfer in the H-bonds in A–T and C–G base pairs.
J. S. Al-Khalili and their colleagues designed an experiment “ Modeling proton tunneling in the adenine thymine base pair and they found out that quantum tunneling, due to transitions to higher energy eigenstates with significant amplitudes in the shallow (tautomeric) side of the potential, is unlikely to be a significant mechanism for the creation of adenine–thymine tautomers within DNA, with the thermally-assisted coupling of the environment only able to boost the tunneling probability to a maximum of 2×109. This is barely increased for different choices of the starting wave function or when the geometry of the potential energy surface is varied.
If we think and imagine it in a deep way then think of the two slits experiment in quantum mechanics, firing a beam of particles, photons, or electrons, through the two slits and you see the interference pattern. Even when you fire one at the time, you can’t explain that interference pattern using classical mechanics, you need quantum mechanics. Well seeing the equivalent of that taking place in certain special mechanisms with living cells, for example, the way enzymes transfer particles from one part of the molecule to another, electrons and later even protons, 2000 times more massive than electrons, they were seeing these protons quantum tunnel from one place to another.
In my opinion, Quantum tunneling can also explain the reason for UV radiation based skin cancer in humans. Like when UV radiation falls on the skin there are chances that photons particle can pass through the skin due to tunneling and likewise, it also reaches the DNA and cause mutation which ultimately causes Skin Cancer by making defective proteins.
References:
Gould, J., 2008. Animal Navigation: The Evolution of Magnetic Orientation. Current Biology, 18(11), pp.R482-R484. DOI: https://doi.org/10.1016/j.cub.2008.03.052
Wiltschko, W., Wiltschko, R. Magnetic orientation and magnetoreception in birds and other animals. J Comp Physiol A191, 675–693 (2005). https://doi.org/10.1007/s00359-005-0627-7
Ritz, T., Thalau, P., Phillips, J., Wiltschko, R. and Wiltschko, W., 2004. Resonance effects indicate a radical-pair mechanism for avian magnetic compass. Nature, 429(6988), pp.177-180.
Trixler, F (2013). "Quantum tunnelling to the origin and evolution of life". Current Organic Chemistry. 17 (16): 1758–1770. doi:10.2174/13852728113179990083. PMC 3768233. PMID 24039543.
Matta, Cherif F. (2014). Quantum Biochemistry: Electronic Structure and Biological Activity. Weinheim: Wiley-VCH. ISBN 978-3-527-62922-0.
McFadden J, Al-Khalili J. 2018 The origins of quantum biology. Proc. R. Soc. A 474: 20180674. http://dx.doi.org/10.1098/rspa.2018.0674
Davies, P. C. W. (2005). "Quantum tunneling time"(PDF). American Journal of Physics. 73 (1): 23–27. arXiv:quant-ph/0403010. Bibcode:2005AmJPh..73...23D. doi:10.1119/1.181015
Panitchayangkoon, Gitt, et al. "Long-lived quantum coherence in photosynthetic complexes at physiological temperature." Proceedings of the National Academy of Sciences 107.29 (2010): 12766-12770.
Waring, S. "Quantum Biology: A Scientific Revolution in our Understanding of Biological Systems." BiolSyst Open Access 7.185 (2018): 2.
McFadden J, Al-Khalili J. The origins of quantum biology. Proc Math PhysEng Sci. 2018;474(2220):20180674. doi:10.1098/rspa.2018.0674
Engel, G., Calhoun, T., Read, E. et al. Evidence for wavelike energy transfer through quantum coherence in photosynthetic systems. Nature 446, 782–786 (2007).
https://youtu.be/bLeEsYDlXJk - An Introduction to Quantum Biology with Philip Ball.
https://www.rsb.org.uk/biologist/158-biologist/features/541-making-the-quantum-leap
Compiling Authors:
Dhairya Rajguru, Kartikey Saxena, Abhishek Mishra, Prithvinath Gollakota, Abhranil Gangopadhayya
Dhairya Rajguru is pursuing Int. M.Sc in Cell & Molecular at Dr. Vikram Sarabhai Institute of Cell & Molecular Biology, The Maharaja Sayajirao University of Baroda. His research interest lies in Molecular Biology & Immunology.
Kartikey Saxena completed BSc. Hons. Zoology from Department of Zoology, Sri Venkateswara College, University of Delhi. His research interests are Cancer Biology, Neurosciences.
Abhishek Mishra completed M.Sc in Microbiology from Mumbai University and right now he is pursuing M.Sc in Biochemistry from The Maharaja Sayajirao University of Baroda. His area of Interest is Frugal Science & to understand Biology which Quantum Physics. He Loves Science Art and Music.
Prithvinath Gollakota completed M.Sc Biotechnology from Department of Biotechnology, Pondicherry University. His research Interests are Protein engineering, Molecular biology, Molecular Genetics.
Abhranil Gangopadhayya is a 1st-year M.Sc Virology student at the National Institute of Virology and he has an undying passion for the enigmatic realm of viruses. He likes to explore more and show the world more about these wonderful spectacles of nature.
Comments