Early RNA Life

Why, though? As a respository for genetic information? RNA can do that too. As a controller for the synthesis of proteins? Proteins can do that on their own.DNA serves required functions in living things, yes. Without a doubt its the best at doing what it does. But it has no functions that other macromolecules couldn't meet, as well. Not to the same degree of effectiveness, which is why DNA is pretty much the standards, but certainly to the degree of sufficiency.

You have been given no real evidence that mud could ever become life. There is a lot of the individual possible steps that have been shown. However, the demonstration of a solid path from non-life to life has not been shown as yet. So?By "real evidence" just what to do you mean? As noted the complete story isn't understood yet. However, there is rather a lot of evidence that suggests that life can arise naturally from non-life. It is not enough to convince everyone yet perhaps but that's fine. More research over the next couple of decades will make it clearer and clearer. We'll just leave it in the "don't know yet" column untill we learn more.On the other hand, you have no demonstartion that life can not arise from non-life. It is in the "don't know yet" column for all of us.Today, almost all life depends on DNA. The minor bits that don't can, I guess, be ignored. So?

It might help if I clarify. I'm just a guy that started thinking about the universe. The theory goes that a hi energy wave,partical, or graviational field started the big bang. This requires the existance of someting before hand. This thinking could go on and on. What caused the wave/partical. There was always someting. So it is with life. DNA is the root of life. There is no life without it, yet there is no DNA without life. Now I'm not a scientist, but I'm no fool either. I've seen alot of criticisum, but the answers i've gotten were either vague, or wrong. Now you are right, as I reread this thread I have made mistakes. I got that. Now could someone please show me a real link between dirt and DNA. If there are none why not. The earth is still turning. Such simle forms must come into being often enough to be able to site many examples. Thats what I'm saying. what! what!

Nosy that is the best post on this subject i've seen so far, and i agree there is a void in this area. That is what makes it such a curiosity for me.

It is widely believed that viri ride comets, and are bruoght to earth quite often. If this is true then it would be natural to assume that would be the start of life on this and many other planets. Don't you agree.This message has been edited by Bob, 11-03-2004 11:11 PM

The idea of new forms of life arising even now is an intriguing one. However, nothing is found. There are a some reasons why we might not expect to see any.One is that the conditions today are not the same as they were 4 Gyrs (4 billion years) ago. Todays environment may not allow for such things to happen.Another is that life may well arise but it would be unable to compete with the life that is already here. All it is is food either as soon as or even before it could actually reach the point of living.Another is that it may arise. However, we don't have a complete, list of all living forms now. And given the rate of evolution of the microbes and the enormous number of them we never will. If the life that rose was just another bacteriophage (viri that live on bacteria) then we'd never notice it.(btw, it was only recently realized that bacteriophages may outnumber ALL the other forms of life on earth by perhaps 10 times! That is, they outnumber ALL the life forms including all the bacteria. It may be that they even out mass all the rest of us. This was only recently realized.)

No, they don't. The prebiotic Earth is a very different place than the modern biotic Earth. Of course, the biggest difference is the presence of already-existing life at this time.All the molecular resources that could be used to form a simple living thing, spontaneously, are already being used by other living things. Unlike the prebiotic Earth there are no free resources for the spontaneous generation of living things.We'll never, ever see spontaneous abiogenesis now. All the other living things keep it from happening. I would have thought that was obvious, especially for someone who's "no fool."

I cannot deny that, but I still have to wonder how it could have possible began. Isn't it a little like a program coding itself. DNA couldn't work at all unless certain parts of the program were intact. There is a large gap between usable DNA and usless junk. an animal would have to carry this usless thing for billions of yrs before it could realize any benefit.

I admitt the things I'm looking for are what life eats.

Maybe, yeah. Incidentally, that's one of the ways we write software nowadays. What thing?

I think most working in the abiogenesis field think that the "first life" was self-replicating RNA. RNA is similar to DNA in that it contains "code" sequence, but RNA is less stable, which is likely why DNA has become the dominant molecule for genetic templates in life.The interesting thing about RNA is that short pieces of it with the proper sequence have enzymatic activity (they act like proteins). This means that a protein-free system made solely of RNA could act as both the genetic template and the enzyme to create more copies of itself.The "first life" was likely such a "replicator", in other words, a short strand of RNA that was capable of making copies of itself. The replicator would have to exist under chemical conditions that gave it the necessary building blocks to make more RNA copies of itself (perhaps the "food" you were asking about, but really more organic chemistry reactions than metabolism).Since RNA can mutate just like DNA, any mistakes made during self-replication that made the RNA replicator more stable or efficient would be selected for. The harsh environment billions of years ago may have accelerated the mutation/selection cycle (especially radiation).This still carries the weight of speculation as Nosy stated above, but is not impossible given experiments carried out in the lab. RNA assembles itself spontaneously and randomly under certain chemical conditions. Labs actually find RNAs that act like enzymes by a process similar to natural selection. First, millions of short random RNA strands are sythesized by purely chemical reactions. Then, the "library" of random RNAs are tested for enzyme activity and selected for further experimentation. In addition to finding short RNAs that copy existing RNA strands (RNA polymerases), short RNAs have also been found that syntesize nucleotides, the building blocks required to assemble RNA.Here are some references, but they are quite technical:The first paper (I believe) on self-replicating RNA.A recent paper describing an RNA capable of synthesizing nucleotides (the building blocks of the RNA strand).Another paper describing an RNA that acts as a polymerase, efficiently and accurately copying another RNA strand.Keep in mind that scientists produce these enzymatic RNAs NOT by designing them, but by selecting them from randomly assembled RNAs. Also, remember that absolutely no DNA or protein is required for any of this to occur.Please let me know if you have any questions.

You have some very good points. I can see how that simple RNA strands could replicate, but a simple strand of RNA is in reality a very complicated molecule arranged in such a way as to hold all the information and mechanics it needs to replicate itself. I can't imagine (how what would be) usless trash could could sit waiting to become so complex as to serve any purpose at all. This would have to take place in a protein molecule I guess, But what use could a protein have with a partial strand of RNA not yet complex enough to serve any purpose?

Since this was my example, I'd like to clarify for you what I thought I'd made plain in my post. At no point did I state that the phage was the "end all explanation" for anything whatsoever. I used it as an example of an extremely simplified genome, and then asked you to define the criteria for "life" that you are using. The problem is that life in this context is a very undefined concept. The scientific definition has run the gamut from something as generic as Edwin Shrodinger's "that which avoids the decay into equilibrium", to "that which undergoes darwinian evolution" to narrowly restricted definitions including many criteria like metabolism, self-maintenance, and self-replication. The phage falls somewhere in the middle. A grey area, as I said.My intent with that post was to try and come to grips with how YOU defined life so that we have some common understanding. If you don't like what I said, all you need to do is define "life" as you wish, then we can talk about possible processes and examples of what lies on both sides of the line, and how they may have arisen (or not, as the case may be).Faith has absolutely nothing to do with my discussion. Please try and read what I wrote. If you need clarification on something I put out there (and I have been accused of being unclear in the past), all you have to do is ask.

My intent was not to insult you, but rather to stear this thread back to the question that I must have been unclear about to begin with. That is how could what we all know as life have grown from what we all know is not life. There is a moment during that evolution (I don't know what else to call it} when that first strand of viable genetic material (probably RNA) began to form. The simplist bit of RNA that could be remotely considered viable is very very complicated, especially if is to take over the job of replicating on its own. I say take over because until it reached the point of viability it would be usless to the thing (I don't know what to call it) that had nurtured it those untold eons it would take to become viable. According to the laws of evolution as I know them. The strand of RNA would need to be of some use to the thing that made it. It would have to reach a very complex point before it could be of any use at all.

Perhaps reread my previous post, since I've already addressed your points of concern there. If you don't understand something, let me know. Short RNA replicators are far less complicated than you seem to think. As I stated before, if you make one million short random RNAs about 25 bases long, some of them WILL have enzymatic activity. 25 bases is not very long, and is easily accomplished with simple chemical reactions without the use of protein or biochemistry.In fact, there are companies that will chemically synthesize strands of RNA for you. Just give them a credit card number, the sequence you want, the amount you want, and they'll produce it with chemical reactions and send it to you in a vial. It's really not that expensive, either. Molecules don't "sit waiting". If a million random short RNAs are made, some of them will have activity. If one of those has RNA polymerase activity, it will immediately have that activity upon its creation, no "waiting" involved... RNA without activity or "purpose" would NOT persist. Those with activity would have that activity at the moment of their chemical origin.There is no such thing as "a partial strand of RNA".And as I said in my previous message, no protein is required for RNA synthesis and replication.There is nothing in your latest reply that was not already covered - if it is due to miscommunication, please let me know.