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Member (Idle past 155 days) Posts: 20714 From: the other end of the sidewalk Joined: |
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Author | Topic: Self-Replicating Molecules - Life's Building Blocks (Part II) | |||||||||||||||||||||||||||||||||||||||
RAZD Member (Idle past 155 days) Posts: 20714 From: the other end of the sidewalk Joined: |
On the Building Blocks of Life (part I) thread I listed my thoughts on the probability of life, reviewing the status our knowledge of the development of pre-biotic chemicals. My conclusion was:
quote: That essay is 3-1/2 years old, and progress has been made in the field of abiogenesis since then, so I would expect much more evidence can be added as reference to the essay on the formation of pre-biotic molecules. While the formation of these molecules are each fascinating in their own right, one of the questions for abiogenesis in how to get from pre-biotic molcules to a self-replicating cells. One of the element critical to that path is the formation of self-replicating molecules. There are many known self-replicating molecules, and a brief listing of some of them is provided below. There is also a large variety of molecules that can self-replicate. Some of the more exciting research (see ref (1) below) confirmed my prediction that self-replicating molecules would compete for resources, and showing how they can dominate the population - chemical evolution: random formation plus selection of the fastest. We can also see a hint of how DNA came to be the dominant replication system in ref (6) below: quote: The DNA outcompetes the RNA production. This does not explain all the questions of how life developed on earth over 3.5 billion years ago, but it goes a long way in showing how possible it was for life to develop from existing chemicals in the conditions that existed in the pre-biotic earth. The sheer number of possibilities also can hint that such processes were quite active, with many variations vying for resources, and that the replication system that life developed from was likely the best at self-replication - the fastest, most stable and aggressive replicators outcompeting their competitors. The likelihood is that, even if they had not existed, that another replication system would have been able to develop into life. Some initial elements of evolution - random variation and feedback selection - were evident in this pre-biotic world. For those who want to visualize how the building blocks from the first thread and the self-replicating molecules mentioned here come together into a pre-biotic self-replicating proto-cell, see this video summary of work from Dr. Szostak: NOTE: this starts with a review of creationist claims, and the actual science starts at about 2:40 into the video. You can move the button ahead to the 2:40 mark and not miss any of the science. You can also turn off the sound, unless you are very fond of Beethoven's 9th Symphony, as there is no narration. Enjoy References: (1) - Artificial molecule evolves in the lab , 08 January 2009 by Ewen Callaway quote: (2) - Self-Reproducing Molecules, Reported by MIT Researchers, 09 May 1990 By Eugene F. Mallove quote: (3) - Self-Replicating Molecules and the Meaning of Life, interview with Dr M Reza Ghadiri, 29 October 1999 by Cliff Walker quote: (4) - Synthetic Self-Replicating Molecules, July 1994 by Rebek, Jr quote: (5) - Evidence for de novo production of self-replicating and environmentally adapted RNA structures by bacteriophage Qbeta replicase., January 1975, by M Sumper and R Luce quote: (6) - Template-free generation of RNA species that replicate with bacteriophage T7 RNA polymerase. July 1996 by C K Biebricher and R Luce quote: (7) - Evolvable self-replicating molecules in an artificial chemistry, Fall 2002 by Tim J. Hutton quote: (8) - Catalytic chirally self-replicating molecule. Asymmetric autocatalytic reaction of a zinc alkoxide of chiral 1-ferrocenyl-2-methylpropan-1-ol, 14 December 1994 by Kenso Soai*, Tadakatsu Hayase and Kazuhisa Takai quote: (9) - Self-Replicating Molecules: A Second Generation, October 1994 by Edward A. Wintner, M. Morgan Conn, Julius Rebek Jr. quote: (10) - Self-Sustained Replication of an RNA Enzyme , 8 January 2009 by Tracey A. Lincoln 1 and Gerald F. Joyce 1* quote: (11) - Intramolecular RNA replicase: Possibly the first self-replicating molecule in the RNA world , 15 August 2006 by Wentao Ma1, 2 and Chunwu Yu3 quote: (12) - A self-replicating ligase ribozyme, 2002 by Natasha Paul and Gerald F. Joyce quote: (13) - A self-replicating peptide, 8 August 1996 by David H. Lee, Juan R. Granja, Jose A. Martinez, Kay Severin & M. Reza Ghadiri quote: (14) - Approaching Exponential Growth with a Self-Replicating Peptide, 22 May 2002 by Roy Issac and Jean Chmielewski quote: (15) - A Self-Replicating Peptide under Ionic quote: (16) - Kinetic Analysis of Self-Replicating Peptides: Possibility of Chiral Amplification in Open Systems , 3 November 2004 by Jesús Rivera Islas1, Jean-Claude Micheau2 and Thomas Buhse1 quote: I also ran across this: http://www.asa3.org/archive/evolution/200011/0202.html quote: Which is what I did. Oldtimers will recognize DNAUnion from this forum. And that's just the start of the 196,000 google hits for "self-replicating molecules". Also see (A) - Did life begin in ice?, 9 August 2005 by Anon. quote: (B) - The RNA World, undated by Brig Klyce quote: (C) - DNA-like Molecule Replicates Without Help, 11 June 2009 by Robert F. Service quote: (D) - Scripps Research Team Creates Simple Chemical System that Mimics DNA, 2009 by Keith McKeown quote: (E) - Synthesis of activated pyrimidine ribonucleotides in prebiotically plausible conditions, 14 May 2009 by Matthew W. Powner1, Béatrice Gerland1 & John D. Sutherland1 quote: (F) - Intramolecular RNA replicase: Possibly the first self-replicating molecule in the RNA world, 15 August 2006 by Wentao Ma1, 2 and Chunwu Yu3 quote: Admin: either as another Columnist article, or in Links and Information? Edited by RAZD, : slight title modification Edited by RAZD, : . by our ability to understand Rebel☮American☆Zen☯Deist ... to learn ... to think ... to live ... to laugh ... to share. • • • Join the effort to solve medical problems, AIDS/HIV, Cancer and more with Team EvC! (click) • • •
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AdminNosy Administrator Posts: 4754 From: Vancouver, BC, Canada Joined: |
Thread moved here from the Proposed New Topics forum.
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Teapots&unicorns Member (Idle past 3638 days) Posts: 178 Joined: |
Quick question- is abiogenesis (possibly) still going on today? Or was it a one-time circumstance?
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RAZD Member (Idle past 155 days) Posts: 20714 From: the other end of the sidewalk Joined: |
Hi Teapots&unicorns,
I think it could still be going on, if it were not for one thing - existing life eating up all the resources. Everywhere you look the are living organisms, sucking up nutrients = amino acids = building blocks. I read once about a microbiologist that sailed across the atlantic, and every day he scooped up some water and looked at it (only a microbiologist would take a lab on a sailboat ...) and every day he discovered new organisms and viruses. Secondly, if it was occurring it would show up in genetic studies as not related to anything. Curiously, there are viruses that attack each of the three main domains of life, with viruses specific for each domain, but which carry common protein markers that show the wear and tear of 3.5 billion years of evolution, and that show they are related. This implies they existed before the three domains. http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=419632 quote: More at: Personally I think they are the remnants of the RNA world. Some people think they should be classified as a fourth domain ... See http://en.wikipedia.org/wiki/Non-cellular_life. quote: ie - RNA world. Enjoy. Edited by RAZD, : last quote by our ability to understand Rebel American Zen Deist ... to learn ... to think ... to live ... to laugh ... to share. • • • Join the effort to solve medical problems, AIDS/HIV, Cancer and more with Team EvC! (click) • • •
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Teapots&unicorns Member (Idle past 3638 days) Posts: 178 Joined: |
Ah. Thanks.
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themasterdebator Inactive Member |
Very impressive post. One question, has anyone been able to show these molecules turning into anything resembling a cell?
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Rahvin Member (Idle past 405 days) Posts: 3964 Joined: |
That's not the point. The transition from self-replicating molecules to cells is not thought to have been the result in a change in those molecules, but rather an accident of environment much later with the addition of an early cell membrane/wall (most hypotheses I've geard of refer to a spontaneously formed bilipid layer). For instance, see Wiki's Abiogenesis entry: quote: The so-called "cellular machinery" (mitochondria, etc) is yet another instance of gradual addition from a variety of pathways. We would be identifying our proto-cell as "life" long before it looked much like a modern cell. The self-replicating molecules are the truly important step, as they allow the process of evolution through natural selection to begin.
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Dr Jack Member (Idle past 855 days) Posts: 3507 From: Leicester, England Joined: |
Two tailed lipids will spontaneously form bilayered spheres (called liposomes), yes, but one-tailed lipids (aka detergents) form micelles (little balls without an inside) instead - and here's the problem - detergents disrupt the formation of liposomes. I'm not sure how this problem is supposed to be addressed.
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greentwiga Member (Idle past 2177 days) Posts: 213 From: Santa Joined: |
Some events are so rare or difficult, that the first time it happens is also the last time. Conditions have changed since the first time, and even if it should happen, it will quickly be killed by life that has had billions of years to increase its efficiency. This is especially true when life needs a chain of several rare steps. For example, RNA needs to become self replicating. Then RNA needs to learn to make RNA that makes protein. Next, RNA needs to make the bilipid layer. Finally, DNA needs to take over some functions that RNA did. Each of these steps could have taken untold millions of years to accomplish. One argument that it only happened once is that all life is left handed.
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RAZD Member (Idle past 155 days) Posts: 20714 From: the other end of the sidewalk Joined: |
From To catch a creationist...
http://www.cosmosmagazine.com/.../life-evolution-a-test-tube quote: Has this been peer reviewed yet? Enjoy. by our ability to understand Rebel American Zen Deist ... to learn ... to think ... to live ... to laugh ... to share. • • • Join the effort to solve medical problems, AIDS/HIV, Cancer and more with Team EvC! (click) • • •
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Coragyps Member Posts: 5548 From: Snyder, Texas, USA Joined: |
Looks like - in Science: http://www.sciencemag.org/cgi/content/abstract/1167856 (as always, I can email pdf's of Science papers on request - PM me. This one will be open access in another week, anyway.)
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finalsky ![]() Suspended Junior Member (Idle past 3543 days) Posts: 1 Joined: |
I have read your passage, I find that it's very useful in application. While there is another way, "Spam.DataSpam", it's fast and stable. Now it's free for everyone, I think it may help. More information:
http://www.spam.spam Edited by Adminnemooseus, : Fix link.
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Hunter Junior Member (Idle past 3478 days) Posts: 1 Joined: |
You say that you think it’s very possible that there was debris left behind from the life cycle of previous stars and planets, but have you ever really looked into or calculated the probability of one protein molecule forming from such debris or mineral like material. The probability of one single protein molecule randomly forming on its own is 2.02 in 10^321. This doesn't even touch the probability of thousands of these protein molecules forming into DNA strands; which turns out to be 1 in 10^40,000.
Setting aside the improbability of protein molecules and DNA strands forming on their own, the chance that our universe could/would be laid out the way it is, is extremely improbable. It's 1 in 10^133, to be exact. The theory you laid out in your second paragraph was nicely done, but it’s only a theory. No one has ever seen this complete process take place. Why would we base our beliefs on the origin of life on a theory? It doesn't seem like life is inevitable from the statistics above. Sources: Peterson, Reichenbach, Hasker & Basinger (2007). Philosophy of Religion Selected Readings (Third Edition). Oxford university press, NY Edited by Hunter, : No reason given.
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fearandloathing Member (Idle past 2895 days) Posts: 990 From: Burlington, NC, USA Joined: |
Hi hunter,
If you could provide a link to your sources I would appreciate it as I can only find reference's to the book and not its content. I am interested to know how they came up with the numbers you cited. "I hate to advocate the use of drugs, alcohol, violence, or insanity to anyone, but they always worked for me." - Hunter S. Thompson Ad astra per aspera
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subbie Member (Idle past 5 days) Posts: 3509 Joined: |
No. Of course, it's difficult to tell exactly what, if anything, you've calculated since you didn't give us the calculation. But I suspect that, if you've calculated anything, it's the odds of a protein molecule coming together in one fell swoop, rather than a step by step combining over a long period of time. Now, if you'd care to actually provide the calculations, I'd be willing to look at them as see if I'm wrong. But I don't think I am. Ridicule is the only weapon which can be used against unintelligible propositions. -- Thomas Jefferson We see monsters where science shows us windmills. -- Phat It has always struck me as odd that fundies devote so much time and effort into trying to find a naturalistic explanation for their mythical flood, while looking for magical explanations for things that actually happened. -- Dr. Adequate ...creationists have a great way to detect fraud and it doesn't take 8 or 40 years or even a scientific degree to spot the fraud--'if it disagrees with the bible then it is wrong'.... -- archaeologist
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