Re: Quantum Biology

Date: Tue, 3 Sep 1996 16:37:32 -0700 (PDT)
From: Lawrence B. Crowell <lcrowell@unm.edu>
To: quantum-d@teleport.com
Subject: Re: Quantum Biology

Replying to: "Quantum Biology,"
http://www.teleport.com/~rhett/quantum-d/posts/clewis_8-30-96.html

On Fri, 30 Aug 1996, Caroline Lewis wrote:

> Very exciting work on microtubules and consciousness has been
> presented by Hameroff and Penrose (1996, ``Toward a Science of
> Consciousness Proceedings,'' MIT Press) which brings together
> fundamental physics and biology. A key question in this work
> is whether or not there are large scale quantum effects which
> directly affect biological processes such as brain function. I
> propose what I would call indicative experiments to test for
> quantum effects in living cells: conceptually simple experiments
> which could indicate whether or not it was worthwhile to do
> more sophisticated tests.
>
> The Hameroff-Penrose conjecture is that there is a gravitationally
> induced quantum coherence in arrays of microtubules (nanometer-sized
> components of the cytoskeleton of the cell which are particularly
> suited to hosting quantum effects because of their crystal-like
> lattice structure, hollow inner core, control of cell division and
> movement and their capacity to process information) at the onset of
> consciousness.

I think that if quantum biology requires quantum gravity then the whole
field is sunk.  It appears difficult for me to imagine how experimental
quantum gravity will achieved.  So to start I am not too interested in
tying quantum biology to string theories or quantum black holes. As much
as I have studied these subjects, I remove myself from them because they
are too far removed from the experimental domain of experience.

My ideas concerning quantum biology tend toward quantum chaos and non-
linear quantum systems.  The coherence on the large is induced by the
self-regulating property of certain nonlinear systems.  The approach I
take is to use the Bohm approach to QM, which I think is physically the
complement of the wave picture (deBroglie wave-particle duality).

The microtubules in cells are sort of quantum transmission lines. There
are microtubule associated proteins that change the ionic environment
of the microtubule. This induces charged oscillations on the microtubule
that satisfy the appropriate boundary conditions for the cylinder.

The ionic medium has a nonlinear permeativity, and when one computes the
Maxwell's equations for this system one finds there is a soliton wave
that travels along the microtubule, which obeys the nonlinear Schrodinger
equation...

>       ...let me briefly outline the experimental ideas:
>

> (iii)New techniques in biophysics may prove useful in looking for direct
> quantum effects in microtubules. For example, optical tweezers (S. Block
> et al., Science, V 270, p. 1653, 1995), can measure the picoNewton forces
> with which a motor protein, kinesin, slides along a single microtubule
> or the enzyme RNA polymerase slides along a DNA strand. The technique
> involves fastening the far end of the microtubule or DNA to a polystyrene
> bead 0.5 micrometers in diameter. This bead is held in a laser interfero-
> meter-based trap (the optical tweezers) and the motor protein tugs the bead
> until the resistance level of the laser beam matches the tugging power of
> the motor protein. A photodetector within the apparatus measures the dis-
> placement of the bead which is then used to calculate the motor force. One
> of the most interesting aspects observed in the real-time dynamics of the
> RNA polymerase and DNA system is that there may be jumps in the position
> of the RNA polymerase, as well as pauses and reversals in the motion.
> The onset of quantum coherence should have an effect on the position of
> motor molecules sliding along the microtubule strands; regular patterns
> may be observed in the distribution of jumps which would not be expected
> from thermal perturbations and which could be different from the ``knocks''
> expected in traveling over bumpy macromolecules.

Neat!

> (iv)Biological perturbation systems: Genetically engineer clean background
> systems of microtubules which can then be perturbed by varying the tem-
> perature, the number of microtubule associated proteins (MAPs), the ions
> present and all the other parameters of a very complex system. Real cells
> are too complicated a physical system to answer a lot of the detailed
> questions concerning quantum coherence in microtubules:

I have the idea of interfacing a microtubule with a "buckytube," a
Buckminsterfullerine that has a complete hex structure and forms a tube.
Thereby the quantum wave could be extracted from a living cell and
maybe run through an interferemetric experiment.

> do MAPs help establish the large scale quantum coherence?

Yes! I very much think they do (see above).

Lawrence B. Crowell