I'm wondering about the significance of the phospholipid bilayer being a two-dimensional fluid.
My question is the following: if you can please explain two-dimensional fluid, please explain the/a/any proximate cause for why the fluid is two-dimensional as opposed to 1 or 3 dimensional.
I'm guessing that based on the powerpoint I found that the limited freedom of movement is optimal for the purposes of the phospholipid bilayer in, let's say, a human brain cell, as having too much freedom in a 3-dimensional fluid would be bad in some way (break apart???), or a 1 dimensional fluid would be bad since fluidity is important for the addition or removal of membrane proteins.
Sincerely, Carlton III
I realized after reading The fluid-mosaic model (Singer and Nicholson, 1972) and Revisiting the fluid mosaic model of membrane structure, I realized that I did not have a basic understanding of the thermodynamic principles espoused in Singer’s article.
So, after combing the internet, I found an essay by Erwin Schrodinger titled “What is Life.” I’ve been reading, and this passage seemed relevant to my question about the significance of the phospholipid bilayer.
“PHYSICAL LAWS REST ON ATOMIC STATISTICS AND ARE THEREFORE ONLY APPROXIMATE And why could all this not be fulfilled in the case of an organism composed of a moderate number of atoms only and sensitive already to the impact of one or a few atoms only? Because we know all atoms to perform all the time a completely disorderly heat motion, which, so to speak, opposes itself to their orderly behaviour and does not allow the events that happen between a small number of atoms to enrol themselves according to any recognizable laws. Only in the co- operation of an enormously large number of atoms do statistical laws begin to operate and control the behaviour of these assemblies with an accuracy increasing as the number of atoms involved increases.” —Schrodinger
It was here that I realized that a higher number of atoms allowed not only for statistical laws to control the behavior of the assemblies, but that the higher amount of smaller parts created a recognizable pattern that conforms to the laws of statistics.
At first glance, It doesn’t matter how large or small the parts are, what matters is how they compose a larger whole due to their behavior, and the behavior is determined by their properties.
Maybe atoms are the “smallest” parts because less surface area allows for more powerful and simple properties. And in relation to biology, more complexity is added to the larger “wholes” that are made of smaller parts.
A single Atom is simpler than a single cell by virtue of cells being comprised of many atoms.
Another thing Schrodinger wrote is this:
“ An entire newcomer should not expect to obtain from the following few pages a full understanding and appreciation of the subject, which is associated with the illustrious names of Ludwig Boltzmann and Willard Gibbs and treated in textbooks under the name of 'statistical thermodynamics'. If you fill an oblong quartz tube with oxygen gas and put it into a magnetic field, you find that the gas is magnetized. The magnetization is due to the fact that the oxygen molecules are little magnets and tend to orientate themselves parallel to the field, like a compass needle. But you must not think that they actually all turn parallel. For if you double the field, you get double the magnetization in your oxygen body, and that proportionality goes on to extremely high field strengths, the magnetization increasing at the rate of the field you apply. This is a particularly clear example of a purely statistical law. The orientation the field tends to produce is continually counteracted by the heat motion, which works for random orientation. The effect of this striving is, actually, only a small preference for acute over obtuse angles between the dipole axes and the field. Though the single atoms change their orientation incessantly, they produce on the average (owing to their enormous number) a constant small preponderance of orientation in the direction of the field and proportional to it. This ingenious explanation is due to the French physicist P. Langevin. It can be checked in the following way. If the observed weak magnetization is really the outcome of rival tendencies, namely, the magnetic field, which aims at combing all the molecules parallel, and the heat motion, which makes for random orientation, then it ought to be possible to increase the magnetization by weakening the heat motion, that is to say, by lowering the temperature, instead of reinforcing the field” —Schrodinger
By lowering the temperature, you lower the environment’s resistance to the behavior of the assembly of oxygen. By doubling the environment, you double the behavior of the assembly of oxygen.
Likewise, maybe, through optimal conditions and or more and more atoms, you are able to increase the output of the behavior that is controlled by statistical laws.
Finally, maybe, the phospholipid bilayer is but one step towards a more complex system. From atoms to molecules, to a whole cell... and optimal conditions or more atoms increase the likelihood of life, from the simplest to the most complex.
Of course, I have no idea what kind of conditions would allow a transition from let’s say a fish to a reptile.
Edit2: So basically, the bilayer being a two dimensional fluid is a function of the distinct parts of the bilayer conforming to statistical laws to create a more complex system by necessity.