The origin and evolution of the Universe is surely the age old problem that for millennia has fascinated thinking persons. That life could arise and develop to the point of thinking, reasoning creatures is an aspect of the larger problem that has caused special fascination. This means that the Universe has reached the stage where it contemplates itself. It also means it is able to fashion machines that can leave this Earth and land on the Moon, and then return, all the while carrying a few of these living, thinking creatures. How splendidly amazing this circumstance is!
In the following paragraphs, I will focus on that aspect of the broader problem we call life. Specifically, I will focus on the origin and evolution of molecular genetics, i.e. the genetic code and its associated protein biosynthesis machinery. This topic is especially interesting because mankind has learned a very great deal about it during the last hundred years and because certain conceptual issues remain unresolved in spite of this great progress. These issues constitute what I mean by the Mysterium Tremendum. My purpose will be to enunciate as clearly as possible what the unresolved issues are. To do this, a review of what is already known is necessary. This review will cover many different features of the problem because so much depends upon the context for the discussion. I hope to be able to eventually point the reader down the correct path to a potentially final resolution, although, for now, that resolution will surely remain out of grasp.
|This account requires a special structure that the modern age of electronic word processing makes possible. While the main text will be presented sequentially, many side issues are presented as needed and where needed in clickable excursions [links]. The reader can choose to take those excursions as he/she sees fit. Often the content of an excursion will be used in the main text, so the excursions are not really optional.
Elements of life
Lipids, membranes and chemiosmosis
The full text of the article is presented in several parts listed in the Table of Contents below.
Table of Contents for Full Article
The Elements of Life
The Physico-Chemical Context for Life
Monomer to Polymer Transition
The Conceptual Issues
Practicing Molecular Algebra
Evolution of the Genetic Code
ur-tRNA and ur-aaRS
Self-assembly, aggregation, and complex formation
Self-assembly of proteins, lipids, and other molecules is a spontaneous process inside cells. The prefix, "self-," is somewhat misleading. This is because visualization of the process
shows a manifest decrease in translational entropy of the components that are coming together.
As such this would be a violation of the second law of thermodynamics. At constant temperature
and pressure, it is the Gibbs free energy that governs spontaneity, not the entropy. Nevertheless,
the apparent decrease in entropy leads to an apparent increase in Gibbs free energy, a violation of
the second law for systems at constant pressure and temperature. The explanation of why no
violation is in fact occurring is given by analysis of the contributions of water molecules to the
process. Upon self-assembly, aggregation and complex formation, displaced water molecules
contribute a big increase in overall translational entropy that more than pays for the increase in
Gibbs free energy of the self-assembling constituents. Only if the water molecules are visualized
and accounted for during the process can the apparent violation of the second law be avoided.
This fact is elaborated [here].
Last updated July 21, 2009.