Quantum Biology: The Spooky NanoWorld of Molecules

We are quite adept in solving numerical problems in our everyday ‘analog world’ using decimal rules developed by us. Digital computers, on the other hand, calculate using binary or Boolean (0, 1) rules, and then convert the result in decimal format with the help of dedicated binary to decimal converter ICs. In the molecular world, calculations ‘happen’ in a strange way.

Take for example the case of Fluorescent Resonant Energy Transfer or FRET. Also known as Forster Resonant Energy Transfer, this phenomenon is characterized by the emission of a photon of one frequency (upon stimulation) which, in turn, activates an acceptor molecule to emit a photon of another wavelength. There’s one clause that says that the first photon (from the donor molecule) will only be emitted when it can definitively be coupled with the ‘acceptor’. But in the first place, how is this ‘virtual photon’ to know whether its bride was waiting or not when it hasn’t even visited her? Yet FRET doesn’t fret, and the process goes on.

All plants use chlorophyll to trap sunlight and convert it to chemical energy in the form of carbohydrates by photosynthesis. The efficiency approximates 100%. The predominant classical approach was that the photons hopped from light capturing pigment biomolecules to the ultimate reaction center where the actual conversion was taking place. But this ‘first choose and then pick’ approach that classical physics suggested would mean considerable loss of energy as heat, as photons wasted time as they hopped down the energy ladder. Quantum mechanics bypassed this by allowing simultaneous sampling of all energy states at one go by its unique properties of ‘superposition’ and ‘entanglement’. Graham Fleming and researchers at Lawrence Berkeley National Laboratory and the University of California at Berkeley showed the existence of a process of ‘quantum beating’, (a phenomenon akin to 'heterodyning’ in radio sets that is used to obtain intermediate frequencies for amplification) occurred which allowed sampling of all energy states by interference of the propagating wave. They used two-dimensional electronic spectroscopy in order to probe the sequence of events that occurred.

That the RBCs (erythrocytes), actomyosin complexes use quantum mechanics for system optimization has been established. Cellular respiration in the mitochondria, DNA, and the brain too might exploit quantum computing.

Counting without disturbing the molecule may be achieved by quantum mechanics, for it allows a molecule to know as if ‘intuitively’, the state of another molecule placed at a distance. Erwin Schrödinger, in his book 'What is Life?', opined that biological systems could be using the principles of quantum theory to maintain biological order. Sir Roger Penrose along with Stuart Hamerhoff proposed that the brain could be working as a quantum computer. In reaction to this, Max Tegmark showed that environmentally induced decoherence would foil any quantum interaction taking place. But Tegmark assumed the average kinetic energy (temperature) of the brain as 310 K (273+37). While this is true in a macroscopic world, Koichiro Matsuno has shown, using black body radiation measurements, that actomyosin complexes which are abundant in the axons of nerve cells, can reach local temperatures as low as 1.6*10-3K. It is as if nature has evolved ways to ensure decoherence free subspaces where entanglement and quantum interaction were possible. Stephen Hawking in his book 'A Brief History of Time' observed that quantum mechanics was the basis of modern biology and chemistry and the only area where quantum mechanics was not properly integrated were gravity and the large-scale structure of the universe (page 60).

To quote Ogryzko "Indeed, if it has taken Humankind only few decades to approach the use of entanglement in quantum information technology, one can wonder why Life, in billions of years of evolution, could not also learn to take advantage, finding in entanglement an alternative resource for stabilizing biological order." It seems we need an entirely different approach if we wanted to probe the mysteries of life and quantum theory is poised to help us in this regard.

P.S. I am glad that the prestigious multidisciplinary journal "NeuroQuantology" published this article with the title "The Spooky NanoWorld of Molecules" and archived it in their "arNQ Eprints and Repository". I thought I could share this with you, my readers!

Last modified: Jun 29, 2010
References:
Quantum Biology
Vasily V Ogryzko (2008). Erwin Schroedinger, Francis Crick and epigenetic stability Biology Direct, 3 (1) DOI: 10.1186/1745-6150-3-15

Of Lightning, Photosynthesis and Electron Transport Chain

We all know that plants use solar energy to form chemical energy in the form of carbohydrates. The suns rays (photons) impinge on the chlorophyll of the green leaves. This excites them and raises them to a higher energy level. These electrons in turn, transfer their energies to another electron nearby and this process goes on till the energy is transferred to the reaction center, where actual conversion of energy is occurring. This energy transfer occurs at a phenomenal efficiency of about 95%. In order to achieve such unprecedented (compared to about 40% in the most efficient solar cells) efficiency, the electrons should 'change hands' in an efficient way and not merely by a random walk.

The electrons do this by 'sensing' and sorting of the energy levels of different electrons (without ever actually having to go to these places for sensing: what Einstein called spooky action at a distance). How the electrons found the right path so as to reach the destination (to electrons with a lower energy level) quickly and efficiently remained elusive. Now scientists perhaps know the reason. These electrons do some kind of quantum computing to arrive at their destinations with unprecedented efficiency.

This premonition of 'unsorted databases' is characteristic of the quantum computing algorithm. Like gamma synchrony, regular patterns of signals lasting several femtoseconds were found, when the chlorophyll molecules were mapped by using electronic spectroscopy. As in dendritic networks, these 'quantum beats' 'bind' (synchronize) all the energy levels of electrons together. Thus these quantum beats help electrons find out the 'path of least resistance' in such an astonishing efficiency. It is as if the energy status of the electrons were indexed as in a computer search algorithm, so that they could be found out faster.

A similar mechanism may be involved in our mitochondria where electron transport chain occurs. Electrons are transported in the mitochondria along a series of electron acceptors to end up ultimately in cytochrome c, where they combine with oxygen, the ultimate electron acceptor, to form water. This chain is very important as it generates ATP, our own energy currency. Quantum entanglement may explain the subject in a new light.

Just a thought in passing, it is said that lightning follows the path of least resistance. I always wondered how it would know where to advance to next, since it had no prior information about what lied ahead. Now, this quantum computational algorithm may be the suitable one to address this issue.