Pre-RNA? Hybrids between proteins and nucleic acids may have helped genetic molecules evolve.
Credit: Science/AAAS
Posted on 06/13/2009 1:07:46 PM PDT by neverdem
Pre-RNA? Hybrids between proteins and nucleic acids may have helped genetic molecules evolve.
Credit: Science/AAAS
Researchers pondering the origin of life have long struggled to crack the ultimate chicken-and-egg paradox. How did nucleic acids like DNA and RNA--which encode proteins--first form, when proteins are needed for their synthesis? Now, scientists report that they've cooked up molecular hybrids of proteins and nucleic acids that skirt the dreaded paradox. Although it's unknown whether such molecules existed prior to the emergence of life, they offer insight into a chemical pathway that might have helped life arise.
DNA and RNA sport a backbone of sugar and phosphate groups linked to the nucleotide bases that spell out the genetic code. Certain proteins help copy nucleic acids by fashioning complementary strands that carry matching nucleotides. But how could nucleic acids originate without proteins, and vice versa? Proponents of the "RNA World" hypothesis argue that RNA itself was the key because of its dual abilities: It not only carries genetic information but also can catalyze chemical reactions. That view received a big boost earlier this year, when researchers at The Scripps Research Institute in San Diego, California, showed that small RNA fragments can catalyze their own reproduction. "The question remains, how those first RNA molecules appeared," says Luke Leman, a chemist at Scripps who was not part of the study. Other researchers have synthesized DNA and RNA analogs with simpler sugar backbones that may have done the job. Yet those are still complex, lessening the chance that they were the primordial replicating molecules, Leman says.
In hopes of finding something simpler, Leman and colleagues did away with the sugar-phosphate backbones altogether. Instead, they turned to amino acids, protein building blocks that have been shown to assemble under prebiotic conditions. The researchers report online today in Science Express that when they combined just two amino acids, a backbone readily assembled without the need for additional enzymes. They then found that DNA bases could bind to a sulfur group in one of the amino acids, cysteine, creating a protein-DNA hybrid strand. But because the nucleic acid bases attach weakly to the cysteines--think Velcro instead of glue--the bases can jump on and off in solution. As a result, when the researchers placed their hybrids in solution with single strands of DNA and RNA, the hybrids were able to rearrange their nucleic acid makeup to form complementary strands that would bind to the DNAs and RNAs. The researchers discovered that the hybrids could also form strands that would bind to other complementary hybrids, which shows that such molecules have the potential to copy themselves.
"This is very interesting and creative," says Eric Kool, a chemist at Stanford University in Palo Alto, California, who studies nucleic acid analogs. These particular hybrids change so rapidly in solution, it's unclear if they would remain stable long enough to propagate genetic information over several generations. However, Kool says, "It's an idea worth considering."
bfltr
“Now, scientists report that they’ve cooked up molecular hybrids of proteins and nucleic acids that skirt the dreaded paradox.”
Sound like smart guys. Hmmm...kinda suggests you need a “smart guy to create life”.
...The researchers report online today in Science Express that when they combined just two amino acids, a backbone readily assembled without the need for additional enzymes. They then found that DNA bases could bind to a sulfur group in one of the amino acids, cysteine, creating a protein-DNA hybrid strand. But because the nucleic acid bases attach weakly to the cysteines--think Velcro instead of glue--the bases can jump on and off in solution. As a result, when the researchers placed their hybrids in solution with single strands of DNA and RNA, the hybrids were able to rearrange their nucleic acid makeup to form complementary strands that would bind to the DNAs and RNAs.
It looks to me like they had help.
Sounds like these guys have edged away from the warm pools thesis into something really different ~ like “self assembly works” ~ no “warm” needed!
You know designing synthetic life producing proteins.
We however are mere products of random luck. Yeah right.....
Sound like smart guys. Hmmm...kinda suggests you need a “smart guy to create life”.
haha why yes..yes it does! They will keep running in circles to avoid you know who :)
DNA is coded information. Information has an order, and has NEVER arrived out of disorder. Order implies intelligence. Someone created the order. Who created that order? We already know. Let the ape descendants choke on that.
before everyone gets into a snit
if they find the right combination of chemicals that breeds life, this does not mean god does not exist.
furthermore, if they do not find the combination, this does not mean god does exist.
Re-Analysis of the Marinov Light-Speed Anisotropy Experiment
News From The American Chemical Society, May 13, 2009 5 summaries & links to articles
FReepmail me if you want on or off my health and science ping list.
And so He can.
This means live is pretty common throughout the Universe, and has similar structures.
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“.......this does not mean god does not exist.”
Well, of course you’re right. Doesn’t prove it one way or the other. But proof of God wasn’t the purpose of the research, though apparently plenty of folks feel terribly threatened by this type of research. Kinda’ makes you wonder how strong their faith is. Feeling compelled to scientifically prove God’s existence, doesn’t have much to do with this research, so one wonders why the creationists feel compelled to inject themselves into it.
What the research does demonstrate, is that the specific reaction process exists. And that is exceptionally neat, and worth pursuing. Good stuff!
Nobody feels threatened by this kind of research. I fail to see why evos constantly project onto creationists feelings of being threatened or having weak faith.
While evos are constantly putting forth this kind of research to show how they think life could have just happened, creationists are merely correcting the false perception put forth that this could have happened on its own by pointing out that what's going on in the lab is nothing less than design produced by intelligence.
Thanks for sharing your insights, dear metmom!
Yep- it’s another ho hum just so story dressed up in designer jeans- The ‘paradox’ of where the info came from in the first place will STILL haunt them to the grave though.
On a sadder note, I’ve intelligently designed ‘purely natural’ playdough which ‘self-replicates’ without any help from anyone (AFTER of course I construct everythign just so with designer elements and ‘playdough hybrid’ goopy stuff) and wouldn’t ya know it? Mr. Bill ‘evolved’ purely on his own!
Kool says, “It’s an idea worth considering.”
***How Kool is that?
“Nobody feels threatened by this kind of research. I fail to see why evos constantly project onto creationists feelings of being threatened or having weak faith.”
Do you truly believe this? I hesitate to point out to you as to why this would be, as I believe that any religious being must, to an overwhelming extent, come to their position by faith. By insinuating themselves into the scientific process (sometimes quite incompetently), it denies the very faith that is a primary component of religious belief. It would seem that if ones faith is based on fundamentalist theology (and many are not), many scientific findings are at odds with that same faith (age of the earth, greater than six “days” for creation, and yes...evolution).
If the basis of your religious belief is primarily faith based, how can you objectively analyze scientific theory? Does one simply pick and choose based on whether it matches what a fundamentalist’s interpretation tells you? How is that an objective analysis of scientific theory? The creationist’s premise is, by definition, preordained (if you will).
There must be an intellectual conflict between these two views of reality (as the basis for each is completely different). I’m just wondering how one can attempt to live in both “worlds”, and rationalize both at the same time. I would think that the obstacles would be insurmountable, (I have viewed such a “dance” as being intellectually impossible long ago, though I have been fascinated by how some exist in such a “bipolar” set of worlds simultaneously). I would think that rationalizing the two “realities” would be impossible, but obviously there are many that try.
If you are truly of faith, why would the scientific process be of such interest to you? I would think that your faith would be personally adequate.
Now that you’ve asked the question, I would like you to respond to the questions I’ve asked. I really mean you no ill will, but I’m truly fascinated by how you, as a creationist, can effectively juggle both reality sets at the same time. They would seem to be like oil and water.
Just tryin’ to see how you do it.
At the same time I was able to create Mr. Bill through the simple expedient of DROPPING PlayDough on the floor.
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