What is the meaning of life (at a molecular level)?

What is the meaning of life at the level of individual molecules?  At what point does an individual molecule attain a purpose that allows it to contribute to living beings?

My favorite example of a “purposeful molecule” is a catalyst.  A catalyst simply helps two reactant chemicals bond more quickly, by reducing the barriers to their pairing, like a matchmaker who gets a couple married more quickly than if they were left alone.  After all is done, the catalyst is left unchanged by the reaction.

Because there are around 1,670,000,000,000,000,000,000 molecules in every drop of water, you can see that there is plenty of opportunity for reactant chemicals to bond on their own (just by accidentally bumping into each other), if they are already predisposed to do so.  The predisposition exists when the product of a reaction is more stable (having less energy) than the individual reactants themselves (i.e. if the married couple is happier together than as separate individuals). 

However, adding a pinch of the right catalyst greatly increases the rate of a chemical reaction, by reducing the barriers for the formation of a bond between the reactants.  Life relies heavily on such catalysts in the body, called “enzymes”, which are made from proteins as specified by our genes.

Still, a catalyst molecule by itself has no meaning, especially when we enclose it in a small box without potential reactants.  Or, more precisely, the catalyst has no meaning in that place and time.  The catalyst is simply a three-dimensional form, without a purpose.

Only when the catalyst exists in the same box as a sufficient number of reactant chemicals does its purpose become clear to an observer.  Its purpose is then defined by the increased rate of chemical reaction, a purpose which is necessary (but not sufficient) for life.  You might say the purpose of the catalyst "emerges" in that context -- or “is discovered” -- where previously there was no purpose.  But unless an external observer makes a record of the event, the catalyst's purpose is lost once the context -- the spacetime box -- goes away.