EA’s 101 on some of the challenges of OOL Chemistry
|January 29, 2013||Posted by kairosfocus under ID Foundations, Origin Of Life, science education|
One of the great things about UD is the commenters. In this case Eric Anderson has put up a summary — some days back — on an aspect of the blind- chance- and/or- necessity- in- a- chemical- stew- in- a- pond (or the like) OOL challenges that is well worth headlining:
>> biological structures are not simply an aggregation of smaller units that naturally come about through the processes of physics and chemistry.
We first need to clarify which building blocks we are talking about. If we are just talking about chemical elements (atoms with their constituent protons, electrons, neutrons) then, yes, everyone agrees that those exist naturally. In addition, if we are talking about some simple molecules, yes, some of those too exist naturally. From there things get more dicey. Specifically, it is not the case, as you suggest, that molecules simply come together as part of a natural chemical process to form amino acids, and subsequently, proteins.
Formation of the amino acids required for life under primitive earth conditions continues to be an active area of research. To be sure, there is evidence that some amino acids can form under primitive earth conditions, and some amino acids have been found in meteorite fragments and in space. However, it is far from certain that all of the necessary amino acids could have existed on the primitive earth at the same time and under the same conditions. (And we are completely setting aside issues such as relative abundance, chirality [NB: –> mirror-image handedness of molecules that affects the possibility of folding etc], cross reactions, and so on.) So the formation/arrival of the amino acids necessary for life to form continues to be an area of interest for the chemical synthesis (to use Davies’ term) origin of life paradigm. Those building blocks are still being studied.
Nevertheless, I am willing to concede for the moment — just for sake of discussion and to help focus us on the real issues — that all the amino acids were readily available at the right time and place. What next?
You [another commenter] mention:
Ditto for amino acids–so long as you line them all up in the right order they just click together and start folding and there you have your protein.
Not really. It turns out that amino acid chains often do not have a single folding pattern. An analogy I like to use is my child’s toy of magnets and rods. In order to make a particular shape it is true that I need to have the magnets and rods in the right order. But while that is necessary, it is not sufficient. This is because the various magnets and rods can cross interact with each other, depending on how the chain is folded. And indeed, we are learning that systems within the cell help to fold the amino acid chain into the right form for the particular protein needed.
Although the formation of proteins has long been portrayed as a simple ‘amino-acid-chain-folds-automatically-into-protein’ situation, that is actually not correct. Given a chain, say 300 amino acids long, there can be many possible folding patterns — most of which constitute a jumbled mess, a few of which constitute functional structures, and perhaps only a couple of which constitute the relevant protein needed for the particular function.
Moreover, even if we were to concede that a chain of amino acids will automatically fold to the correct protein, that still leaves unanswered the $64,000 question that you gloss over with “. . . so long as you line them all up in the right order . . . .” This ordering is precisely the issue that cannot be solved by natural means within the resources of the known universe.
Beyond proteins, we have protein complexes, then larger molecular structures (for example, the molecular machines often discussed), organelles, cells, organs, larger systems, and the entire physical organism itself. All of this can, in the sense Davies is discussing, be termed “hardware.”
My point is that current chemical synthesis efforts don’t even scratch the surface of dealing with all the hardware. Right now they are still stuck back at the amino acids and proteins — what are often referred to as the “building blocks” of life.>>
This brings down to 101 level, several of the key challenges for OOL (that, unfortunately, are too often glossed over in the classroom, as well as in popular science documentaries and on “science” web sites), and for the onward production of novel types of proteins as well.
Well worth pondering. END