First post, but hopefully a valid question

[BTF/PTM]

Hi everyone,

 

I couldn't find a 'beginners forum' or something of that nature to put my first post in, so here it is in this one as this forum is related to my first question. Hi all =)

 

Ok, so here is my question, with a bit of preamble to give it validity. Along with my general curiosity on all science topics, from engineering to genetics to astronomy to paleontology, I have developed a new curiosity for the ongoing debate of where life on our planet first came from. I generally understand the theorized process of how chemical compounds became amino acids that eventually became very large coils of proteins that eventually became what we identify as genetic code. I also understand that various steps in this process have been verified under lab conditions. What I do not understand in all this, is the term 'self-replicating', as pertains to the critical step at which the proteins are able to produce copies of themselves. The misunderstanding, I think, comes from my own missing bits of microbiology and molecular biology knowledge, and that's what I've come here to ask for. That question is, what is the science behind how these proteins are considered self-replicating?

 

As my own mind envisions this process, using the function of a single cell as its example, these proteins in fact do not in any fashion replicate themselves in the simple sense of spontaneously sprouting extensions of every adjoined compound and eventually producing some siamese twin molecule. As I envision it, these complex proteins in fact developed ALONG WITH groups of other complex molecules, including the disassemblers, reassemblers, enzymes, etc etc etc. In other words, for the self-replicating proteins to have originated, many other complex molecules had to develop in parallel that allowed them to replicate.

 

A mental picture of duplicating a city building could be used, I suppose - a building (which is just as inanimate as a complex protein molecule) cannot replicate itself, but with materials on hand and an army of helper molecules (workers) that are good at tasks like arranging these materials and reverse-engineering the building and supporting various intermediate structures, copies of the buliding could be produced with high efficiency and high accuracy. From a sufficiently high altitude, one may only see the large chunks of the buliding shaping themselves and draw the conclusion that somehow this structure is duplicating itself.

 

Is my idea anywhere near correct? As a related side note, if anyone can provide links to essays or papers written on the idea, I'd welcome the info. As aforementioned, I ask this question only because I feel I don't understand it (along with many many other people) because I am missing pieces of information.

 

Thanks, everyone =)

[EdEarl]

Your long post challenged my dyslexic brain, but I think you want to know about how life came about. The answer is, nobody knows. Thus, I will not speculate about your speculations.

[Ophiolite]

I echo EdEarl's observation. The picture you painted of our understanding of abiogenesis is a fairly accurate version of what is often publicly presented. The truth is we have many ingenious ideas as to the steps involved, but little or no confirmation of any of them. There is a strong tendency to gloss over weaknesses in hypotheses, or to treat provisional assumptions as if they were established fact.

 

Let me illustrate these problems with an example. You are probably familiar with the experiments conducted by Stanley Milller under the direction of Harold Urey. Amino acids were produced when electric sparks were generated in a reducing atmosphere of ammonie, methane, water vapour, etc. This experiment was important, in my view, not for the results, but for the demonstration that perhaps the origin of life could be investigated experimentally. It has been repeated many times with many variations in the experiemental set up and the atmospheric composition. What is rarely mentioned and almost never emphasised is that most of these tests produce either nothing, or incredibly low yields and that they are remarkably sensitive to the physical structure of the apparatus.

 

We still debate the nature of the primeval atmosphere and cannot even agree on whether or not it was reducing. Even those versions of the experiment generating amino acids do not produce ones that are handed, as is the case with all biological amino acids. Nor are the amino acids produced a decent reflection of the twenty or so found in terrestrial life.

 

This level of ignorance may sound depressing, but it should be embraced as a magnificent field in which to investigate. Which is more exciting? Editing the works of a literary genius for small grammatical errors, or being a literary genius? I know where my money is placed.

[BTF/PTM]

Thanks for the replies! They do help, but my question is not the cliche of where life came from. I fully understand that we as a species do not understand how that works, and I also accept the notion that we may never know.

 

Here's another version of my question, maybe it will help those of us who suffer from occasional dyslexia, myself included =)

 

I am asking specifically about the mechanism of how RNA self-replicates. My preposition is, I think the term 'self-replication' is misused, which is to say that a molecule of RNA, the basis of living DNA-based tissue, does not look in a mirror and consciously decide to split in two and spontaneously generate duplicate chemical compounds and end up with a twin of itself. I would envision RNA 'self-replication' as being a process of not only the eventual development and existence of RNA, but also the development and existence of all the enzymes and proteins that actually perform the 'self-replication' in a series of steps including disassembly, reading, protein formation and eventual assembly of a second RNA strand.

 

To sum it up, my preposition is that RNA does not actually 'self-replicate', it is a process involving many types of molecules that all had to develop in order for the basis of life to develop the capability of duplication. I draw this preposition from the basic understanding of how individual (but complete) cells replicate, they use a small army of helper molecules to build new RNA and DNA, their RNA and DNA do not wake up each morning and decide to make twins of themselves. They make copies of themselves with extensive help from many other molecules, but they do not 'self-replicate'.

 

Correct? Incorrect? This is the information I'm looking for. Thanks again!

[Ophiolite]

Your questions seems based on the understanding that early biochemistry was based on RNA, not DNA. You seem to be thinking in terms of what is called The RNA World. I don't subscribe to the notion that this existed, therefore my suspicion is that RNA did not self replicate. I appreciate that that is not very helpful for you. It is also a minority view, so perhaps a believer will provide the specific interpretation you are looking for.