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Origin of Life

Discussion of everything related to the Theory of Evolution.

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Origin of Life

Postby Morgyn » Fri May 02, 2008 11:38 am

I'm just starting a unit on evolution etc. and we have been looking at some of the different theories on the origin of life. I've been fascinated by this topic for a while and am interested in hearing some opinions/comments on the theories and maybe finding our about some lesser known ones also.
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Postby alextemplet » Fri May 02, 2008 4:41 pm

Are there any questions in particular that you wish to ask? That's a very broad topic to discuss without having something specific in mind.
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Re: Origin of Life

Postby Morgyn » Sat May 03, 2008 1:44 am

Well we've just started the theory that life started at incredibly low temperatures, and then also the lightening creating molecules that are found in living organisms etc. So any comments on those would be interesting, but also just people's opinions on which theory (or theories I suppose) they believe to be the most plausible and why.
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Postby alextemplet » Sat May 03, 2008 5:16 am

I think I remember reading something about that but it was years ago and my memory's rusty. I have read a very interesting theory that life originated with completely RNA-based organisms, in which the RNA strands served all the necessary functions now performed by not just RNA but also DNA and proteins. I'll have to dig out one of my books on it but it was fascinating how RNA might be able to take on those additional roles.
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Re: Origin of Life

Postby Morgyn » Sat May 03, 2008 6:19 am

Yeah, I just read an article on the theory that life began in ice and it also has the 'beginning from RNA-based organisms' opinion. Rather than do a terrible job of trying to explain it, I looked it up and, lo and behold, there it was on the net.

http://discovermagazine.com/2008/feb/di ... lve-in-ice

I'm not sure if it's exactly the same one, but it seems to be along the same lines and written by the same guy. Anyway, it blew my mind and I thought other people might be interested in reading it. After reading it, personally, the ice theory looks pretty good to me but I'd love to hear what you think (and let me know if there's anything interesting in the books you dig out) :D
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Postby AstusAleator » Sun May 04, 2008 7:28 pm

Fascinating article, and it set me off on a whole trail of reading about the moons of Saturn and Jupiter and whatnot. Great stuff. good post. If could boost your points on this forum somehow I would.
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Re: Origin of Life

Postby Morgyn » Mon May 05, 2008 5:58 am

Thank you! I also thought this article was amazing, especially the bit about the moons and planets (oddly enough no-one else in my biology class quite got into it as much as I did). I haven't actually looked at anything else on them (though now you've given me the idea I might) but I did get carried away with trying to use the evidence provided to work out the step by step process of the birth of RNA (but as this is only my second year of college [highschool to the yanks] biology I didn't get very far). I still haven't heard much about the other theories but I'm sure some of them must be at least almost as plausible as this one.

PS Did you find any interesting information about the moons? Let me know if there were any sources of particular interest.
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Re: Origin of Life

Postby jasonP » Tue May 13, 2008 1:02 am

As of 2005 biologists believe that very early in Earth's history the simple chemicals: Carbon Monoxide, Carbon Dioxide, hydrogen, ammonia, water, and nitrogen were present in the atmosphere. Sunlight produced energy for these chemical compunds to undergo redox reactions with each other. As a result, more complex chemicals such as Formaldehyde and Hydrogen Cyanide formed. As the compounds were heated further they reacted to form even more complex chemical molecules such as acetaldehyde, glycine, and ribose (a sugar). Inestingly, as you may know, some of these molecules are essential to life and are found in our bodies. Eventually, these chemicals were dissolved into rainwater and then fell into oceans.


At this point, biologists believe these chemicals reatced to form a strand of RNA. RNA is known to self replicate. So there is the most important aspect of the first living entity. It is replication. Movement, consuming food particles, and cellular life was not the first living entity. The single ability to self-replicate defined the RNA chemical strand to be alive. This idea of chemicals changing through time and eventually producing a self-replicaitng chemical compund is called chemical evolution. Oddly, biologists don't know how chemical evolution led to the creation of RNA. They do however believe that it did, and they are also certain about the formation of the previous chemicals I mentioned.

I hope you found my rant informative! Please let me know what you think.


I do believe this theory to be plausible because chemical reactions do form these molecules in the laboratory. Further scientific evidence regarding lipids and nucleic acids also makes this theory sensible. The major flaw is how chemical evolution created RNA.
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Re: Origin of Life

Postby jasonP » Tue May 13, 2008 2:14 am

I just read the discover article and I must say it is fascinating! Interestingly, it refutes everything I just said in my last post! How could have the molecules react in the sea ice without a heat source in the ice?
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Re: Origin of Life

Postby Morgyn » Tue May 13, 2008 7:24 am

Your rant was very informative and I don't think the article necessarily refutes your argument because there's nothing in the rule book (that I know of) that says that these things couldn't have both happened. As for the energy source for molecule reactions I think it explains in the article that because the pockets in the ice were small the impurities that were contained in them became crowded together, kind of bumping into each other and forming other compounds (if you have a look at the article again it may explain it better).
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Re: Origin of Life

Postby jasonP » Tue May 13, 2008 2:42 pm

So according to the article a heat source was not needed. It was the close proximety of particles that allowed them to react with each other. That is a sensible theory. The information I told you was from my college Biology textbook copyrighted 2005 so it is accurate to a certain extent. But you are correct because most theories are just theories! Obviously no one has proven the true origin of life... yet. I think that as long as scientists have explanations for the orgin of life that can be tested and proven to a certain extent it is probably a plausible theory, which obviosuly means there are many.
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Re: Origin of Life

Postby Morgyn » Wed May 14, 2008 7:11 am

Yeah, I agree with what you said. There are a lot of theories that could work (life from space etc.) as well, and it was good to have the one from your text book as in my original post I did want to know about other theories and what people thought of them. Also, with my very limited science, it seems possible that they each could have contributed i.e. Earth was frozen, the RNA formed and then after Earth thawed out a bit the chemicals that had been created with heat mixed with the RNA etc. etc. until we get more organisms forming.

Really I'm not too fussed about who is right and wrong, I just like discussing the theories :)
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