Physical Model of Cell: Know All About It

[Pythagorean]

Is there a physical model of the cell developed or being developed?

I'm nearly a physics graduate, but I'm starting to get interested in cells, they're like amazing little factories.

 

[BioCore]

Sorry for asking this, but your question got me a bit interested. I was wondering if you could explain simply what a Physical model of the cell would be - something like a mathematical model or not?

 

[Pythagorean]

I'm not sure I want to confine it too much by answering it :P

I guess the main idea would be that it's approached from physical principals rather than chemical ones.

Of course, the obvious answer would be to model all the reactions and motions of constituent molecules, but that sounds really complex from a physical point of view (i.e. quantum mechanics).

The idea in its purist form would be a trained physicist that knows nothing about biology pick up a cell and say "what is this strange thing?" and start poking it and prodding it with his physics training to find out its properties.

 

[Andy Resnick]

There's lots of cell models- even programming languages to probe the response to a particular input:

http://xml.coverpages.org/cellML.html
http://www.sysbio.org/
http://www.nrcam.uchc.edu/
http://www.physiome.org/Links/index.html

There's also a lot of work modeling organ-level systems. I'm most familiar with models of the nephron, but there's also tons out there on neuron networks, for example.

 

[Moridin]

Are we talking cell division or abiogenesis/evolution here?

 

[Mapes]

Is there a physical model of the cell developed or being developed?

This is an area of very active research. There is disagreement in the literature about whether it is best to treat a cell physically as a sack of salt water, a hydrogel, a viscoelastic polymer, a network of biopolymeric struts, a combination of these, something else, or simply as a cell (i.e., a unique collection of mechanical responses that can't be compared to anything more familiar). Sometimes it reminds me of how our knowledge developed about photons and other fundamental particles, which have wave and particle properties but ultimately cannot be reduced to anything familiar on the macroscopic scale.

 

[Pythagorean]

thank you all for the links and terminology

Are we talking cell division or abiogenesis/evolution here?

I was just speaking in general.

Abiogenesis would be neat. I've always loved to hear theories about how mitochondria (sp?) could have once been a bacteria that invaded a cell and formed a symbiotic relationship with it.

 

[Charion]

Of course, the obvious answer would be to model all the reactions and motions of constituent molecules, but that sounds really complex from a physical point of view (i.e. quantum mechanics).

Heh, kind of sounds like what systems biology likes to do.
Just to clarify though, abiogenesis questions how life emerged from non-life. Everything regarding mitochindria and endosymbiosis is, of course a matter of living organims and hence not the topic of abiogenesis.

To answer your question: AFAIK there are no serious attempts do define a physical model for something as complex as a cell in any depth. However there are plenty for a number of (sub-)cellular interactions, like e.g. cell-surface interactions, protein-protein interactions and so on.
Or rough models that target certain global properties of the cells (like e.g. impedance).

 

[Pythagorean]

Heh, kind of sounds like what systems biology likes to do.
Just to clarify though, abiogenesis questions how life emerged from non-life. Everything regarding mitochindria and endosymbiosis is, of course a matter of living organims and hence not the topic of abiogenesis.

I suppose I knew that (I didn't separate abio and evolution in my response) . Just out of curiosity though, at one point do you define that transition between non-life and life? I sense in general that the idea is that a bunch of proteins ordered in the right way got zapped with the right amount of energy that started some perturbations in the right spatial dimensions that were somehow right to make an oxygen engine basically.

 

[Andy Resnick]

The issue of what distingushes living from non-living is one of the great unanswered questions of our time. A fire, for example, displays every characteristic we associate with living systems-it moves, eats, breathes, grows and reproduces, excretes, etc.

Kaufman's book "The Origins of Order" has some interesting ideas.

 

[Charion]

Only that fire itself is not an entity but rather a chemical reaction. Beside that point, however there are indeed really conclusive definitions of live. All that I know of are in fact derived based on an a priori distinctgion. That is, first a distinction between life and non-life was done and then the observed differences were used to define what was classified beforehand as live.
Chances are that the the distinction (as almost always) are not as strict as often assumed.