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DNA help needed!

Johnny Pixels

Graduate Poster
J
Joined
Nov 24, 2005
Messages
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Ok, I'm in a shooting match with creationists, except I really don't know much about DNA, having never studied it at school.

So far my basic argument for origins of life has been that organic molecules like hydrocarbons form themselves into long chains from modular pieces. From what I understand of DNA this also forms long chain molecules, but the different combinations of modules is what carries the information. Therefore, there are stages between things like non-living hydrocarbon chains and DNA, I'm not claiming that hydrocarbons one day decided to form DNA. I'm just suggesting that there is order in the nucleus and electron arrangement of atoms, there is order in the formation of molecules, molecule chains, chemical compounds, why is the formation of ordered DNA so far fetched?

So, my question is, am I talking complete rubbish?

And where's a good place to learn about DNA, in not too technical terms?
 
Johnny Pixels said:
Ok, I'm in a shooting match with creationists, except I really don't know much about DNA, having never studied it at school.

So far my basic argument for origins of life has been that organic molecules like hydrocarbons form themselves into long chains from modular pieces. From what I understand of DNA this also forms long chain molecules, but the different combinations of modules is what carries the information. Therefore, there are stages between things like non-living hydrocarbon chains and DNA, I'm not claiming that hydrocarbons one day decided to form DNA. I'm just suggesting that there is order in the nucleus and electron arrangement of atoms, there is order in the formation of molecules, molecule chains, chemical compounds, why is the formation of ordered DNA so far fetched?

So, my question is, am I talking complete rubbish?

And where's a good place to learn about DNA, in not too technical terms?
Click to expand...


I'd start with talk.origins archives as a resource:
http://www.talkorigins.org/faqs/abioprob




I'd also rewind a bit on the example: you have the general idea, but abiogenesis models do not assume DNA specifically was involved in early life. Any polymerizing molecule can become self-replicating, given the right sequence of components. RNA is a more farvoured candidate, as there are examples today where RNA strands have the dual function of information storage and enzyme. DNA is proposed to have evolved later, to fill an archival role. We may never know what composed early self-replicating molecules.

I'd also rebuff arguments about 'order'. Creationists - and in particular IDers - use the term all the time, but not in a scientific manner. (ask them what the SI units are for 'order' and how they measure it objectively)
 
blutoski said:
RNA is a more farvoured candidate, as there are examples today where RNA strands have the dual function of information storage and enzyme.
Click to expand...

I said enzyme, but catalyst is probably a better word.
 
The original genetic material was most probably not even RNA but some other related molecule wot we dont know nuffink of yet.
 
Johnny Pixels said:
So far my basic argument for origins of life has been that organic molecules like hydrocarbons form themselves into long chains from modular pieces. From what I understand of DNA this also forms long chain molecules, but the different combinations of modules is what carries the information. Therefore, there are stages between things like non-living hydrocarbon chains and DNA, I'm not claiming that hydrocarbons one day decided to form DNA. I'm just suggesting that there is order in the nucleus and electron arrangement of atoms, there is order in the formation of molecules, molecule chains, chemical compounds, why is the formation of ordered DNA so far fetched?

So, my question is, am I talking complete rubbish?
Click to expand...

You're not talking rubbish and you're on the right track, but I'm afraid you may be taking huge leaps. The chemical history from hydrocarbon chains to DNA is probably emence. You may be setting yourself up for "and then a miracle occurs" argument if you don't have all your ducks in a row.
 
Cool, thanks for the replies.

I was trying to give them idea that hydrocarbons have a repeating modular structure, why can't that lead to the repeating structure of DNA, through a number of steps, of course. There's no need to put "God did it" in between the two, as theres not an impassable gulf between them. I'll not to get in over my head though.


:rolleyes:




:boxedin:




:idea:
 
Here is a paper describing the current state of knowledge, although the problem is far from solved:

biology.plosjournals.org/archive/1545-7885/3/11/pdf/10.1371_journal.pbio.0030396-S.pdf

The most important thing to remember is that a lack of a consensus among scientists about abiogenesis in no way proves that god or aliens or any other intelligence was involved in the process. I know that seems pretty obvious but that's the claim creationists ussually make. Addiditionally, a lack of a full theory of the origin of life is no obstacle to the theory of evolution, which only requires life comes into existence by some means. It is definately worth checking out the talkorigins website linked above, as it has an answer to pretty much every creationist argument you can think of.
 
It is theorized that RNA preceded DNA.

So how did RNA form? Well, experiments do show that layered mineral deposits can attract, concentrate and link organic molecules, and that certain clays can act as “scaffolding” for assembling the molecular components of RNA – see Robert Hazen, “Life’s Rocky Start”, Scientific American April 2001.

The hypothesis goes that (1)neucleotides (sub units of RNA) link together to form RNA, then (2)RNA strands become housed inside a fatty acid membrane, that becomes like a cell (ie it could divide and grow). A clay, called montmorillonite, has been shown to do this. From the famed science writer Carl Zimmer:

In the 1990s biochemist James Ferris of Rensselaer Polytechnic Institute showed that montmorillonite can help create RNA. When he poured nucleotides onto the surface of the clay, the montmorillonite grabbed the compounds, and neighboring nucleotides fused together. Over time, as many as 50 nucleotides joined together spontaneously into a single RNA molecule. The RNA world might have been born in clay, Ferris argued, perhaps the clay that coated the ocean floor around hydrothermal vents.

“The thing that’s interesting is that there’s this one mineral that can get RNA precursors to assemble into RNA, and membrane precursors to assemble into membranes,” says Szostak. “I think that’s really remarkable.”

As Hanczyc and Fujikawa analyzed their new vesicles, they made an even more remarkable discovery. Some of the grains of montmorillonite actually wound up inside the vesicles.

Their next step was obvious. “It was very straightforward,” says Hanczyc. “You just mix the RNA with clay, and mix it with the fatty acids, and voilà, you have RNA on the clay particles inside the vesicles.”

Here was one possible way in which the pieces of the RNA world might have come together in cells that could grow and divide.
Click to expand...
Just one possible route, of course.
 
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