Freethought & Rationalism Archive

tgamble · 08-05-2002, 07:26 PM

These two posts
<a href="http://forums.sympatico.ca/WebX?14@88.qkASab2Mw4j^23767@.eeb50e7/37897" target="_blank">http://forums.sympatico.ca/WebX?14@88.qkASab2Mw4j^23767@.eeb50e7/37897</a> <a href="http://forums.sympatico.ca/WebX?14@88.qkASab2Mw4j^23767@.eeb50e7/37898" target="_blank">http://forums.sympatico.ca/WebX?14@88.qkASab2Mw4j^23767@.eeb50e7/37898</a>

make many claims about the alleged improbibility of a cell forming by natural means. ie

Quote:

During the l980s and early 1990s, National Institutes of Health (NIH) researcher Norman Gersfeld successfully addressed the question of how it is that cell membranes consist of a single bilayer when phospholids form multiple-layer sheets or relatively unstable single-bilayer vesicles. (N. L. Gershfeld, "The Critical Unilamellar Lipid State: A Perspective for Membrane Bilayer Assembly," Biochimica et Biophysica Acts 988 (1989): 335-50.

On a search for Norman Gersfeld + phospholids I got no results. Anyone familiar with this research?

Any comments on the rest of the posts would be appreitated.

Also, the two posts don't look like they are unique. ie. I suspect they were copied from somewhere but I can't find out where from. Assumeing it was copied at all of course.

Thanks!

(if the links don't work, let me know and I'll copy the posts here directly.)

Albion · 08-05-2002, 08:41 PM

Just to be going on with, I looked the name up on PubMed (it's Gershfeld, not Gersfeld) and found this lot. I think you'll find some abstracts there.

<a href="http://www.ncbi.nlm.nih.gov:80/entrez/query.fcgi?CMD=search&DB=PubMed" target="_blank">http://www.ncbi.nlm.nih.gov:80/entrez/query.fcgi?CMD=search&DB=PubMed</a>

Wonder if he knows his work is being cited by creationists.

[ August 05, 2002: Message edited by: Albion ]

Doubting Didymus · 08-05-2002, 10:54 PM

For crying out loud, don't creationists have ears? how many times do we have to shout from the hilltops 'No-one thinks the first living thing was a cell, a DNA strand, an RNA strand, or anything like that level of complexity'.

Why don't they just stop?

tgamble · 08-06-2002, 03:51 AM

Quote:

Originally posted by Doubting Didymus:
For crying out loud, don't creationists have ears? how many times do we have to shout from the hilltops 'No-one thinks the first living thing was a cell, a DNA strand, an RNA strand, or anything like that level of complexity'.

Why don't they just stop?

Because they are stupid and/or dishonest?

tgamble · 08-06-2002, 04:11 AM

Quote:

Originally posted by Doubting Didymus:
For crying out loud, don't creationists have ears? how many times do we have to shout from the hilltops 'No-one thinks the first living thing was a cell, a DNA strand, an RNA strand, or anything like that level of complexity'.

Anyone know of any good articles that discuss the predessurs to RNA?

theyeti · 08-06-2002, 08:12 AM

Having looked through that post, I'm not sure what the point is. I haven't looked up Gershfeld's (sp?) work, and I'm not that familiar with lipid chemistry, but your friend seems to be spinning his wheels. Phospholipids will spontaneously form bilayers in an aqueous solution, and will make structures that are spherical and resemble small cells without any outside help. In fact, one hypothesis about the origin of life has to do with self-replicating proteinaceous membranes, which later incorporated nucleic acids and such. Researchers have made proteinaceous proto-cells using rather mundane processes -- check out work by Fox (<a href="http://www.ncbi.nlm.nih.gov:80/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=189159 2&dopt=Abstract" target="_blank">here's a PubMed abstract</a>).

The discussion about temperature simply doesn't make any sense to someone trying to find evidence for ID. The melting point of a cell membrane is known to vary widely depending on the types of phospholipids present, the presence of cholesterol, and the protein content. Citing cases where some membranes are adapted for various temperatures just shows that they can be adapted for various temperatures -- duh. The person here is trying to make a "everything is just right" fine-tuning type argument, but incredibly he cites cases where membranes can exist in widely varying temperatures. Like I say, it doesn't make much sense. And of course, it suffers the same problem as all fine-tuning arguments: is the evironment fine-tuned for life, or is life fine-tuned for the environment? Obviously, one expects living things to be adapted for the enivronment that they're found in, otherwise they wouldn't be there. And then there's the usual fallacy of ID thinking: we don't know off-hand of a natural process, therefore a space Goddidit. God of the Gaps, but with very tiny gaps.

I would suggest just looking through PubMed on cell membrane evolution and Fox's protocells. Hit 'em up with that -- they've probably never seen this kind of research, which is typical.

Oh yeah, the bit about the seasons is really stupid. People who live at the equator, where most life is found, don't experience seasons like we do.

theyeti

theyeti · 08-06-2002, 08:28 AM

Quote:

Originally posted by tgamble:


Anyone know of any good articles that discuss the predessurs to RNA?

<a href="http://www.ncbi.nlm.nih.gov:80/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=929929 6&dopt=Abstract" target="_blank">J Theor Biol 1997 Aug 21;187(4):523-7</a>

Speculation on the RNA precursor problem.

Quote:

While no convincing prebiotic synthesis of RNA building blocks has been demonstrated, at least two synthetic analogues of nucleic acids have been described whose properties are remarkably similar to those of RNA. The RNA backbone is thus not the only possible solution to the problem of replicating the information stored in a sequence of purines and pyrmidines. These results indirectly support the suggestion that RNA might have been preceded in evolution by a related molecule which, perhaps, was more easily synthesized than RNA. New results on the prebiotic chemistry of phosphonic acids suggest a possibility that a backbone structure based on ribose-2,4-diphosphonic acid may have formed via some surprisingly simple chemistry.

Also, off hand I can think of at least two other palusible RNA precursors that have been studied for abiogenesis: PNA and thioesters.

Heck, while I'm at it:

<a href="http://www.ncbi.nlm.nih.gov:80/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=811516 3&dopt=Abstract" target="_blank">Orig Life Evol Biosph 1993 Dec;23(5-6):323-7</a>

Peptide nucleic acid (PNA): a model structure for the primordial genetic material?

Quote:

It is proposed that the primordial genetic material could have been peptide nucleic acids, i.e., DNA analogues having a peptide backbone. PNA monomers based on the amino acid, alpha, gamma-diaminobutyric acid or ornithine are suggested as compounds that could have been formed in the prebiotic soup. Finally, the possibility of a PNA/RNA world is presented, in which PNA constitutes the stable genetic material, while RNA which may be polymerized using the PNA as template accounts for enzymatic activities including PNA replication.

theyeti

theyeti

08-05-2002, 08:41 PM	#2
Albion Veteran Member Join Date: Jul 2002 Location: US east coast. And www.theroyalforums.com Posts: 2,829	Just to be going on with, I looked the name up on PubMed (it's Gershfeld, not Gersfeld) and found this lot. I think you'll find some abstracts there. <a href="http://www.ncbi.nlm.nih.gov:80/entrez/query.fcgi?CMD=search&DB=PubMed" target="_blank">http://www.ncbi.nlm.nih.gov:80/entrez/query.fcgi?CMD=search&DB=PubMed</a> Wonder if he knows his work is being cited by creationists. [ August 05, 2002: Message edited by: Albion ]</p>

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08-05-2002, 10:54 PM	#3
Doubting Didymus Veteran Member Join Date: Jul 2002 Location: East Coast. Australia. Posts: 5,455	For crying out loud, don't creationists have ears? how many times do we have to shout from the hilltops 'No-one thinks the first living thing was a cell, a DNA strand, an RNA strand, or anything like that level of complexity'. Why don't they just stop?

08-06-2002, 08:12 AM	#6
theyeti Veteran Member Join Date: Jun 2001 Location: Denver, CO, USA Posts: 9,747	Having looked through that post, I'm not sure what the point is. I haven't looked up Gershfeld's (sp?) work, and I'm not that familiar with lipid chemistry, but your friend seems to be spinning his wheels. Phospholipids will spontaneously form bilayers in an aqueous solution, and will make structures that are spherical and resemble small cells without any outside help. In fact, one hypothesis about the origin of life has to do with self-replicating proteinaceous membranes, which later incorporated nucleic acids and such. Researchers have made proteinaceous proto-cells using rather mundane processes -- check out work by Fox (<a href="http://www.ncbi.nlm.nih.gov:80/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=189159 2&dopt=Abstract" target="_blank">here's a PubMed abstract</a>). The discussion about temperature simply doesn't make any sense to someone trying to find evidence for ID. The melting point of a cell membrane is known to vary widely depending on the types of phospholipids present, the presence of cholesterol, and the protein content. Citing cases where some membranes are adapted for various temperatures just shows that they can be adapted for various temperatures -- duh. The person here is trying to make a "everything is just right" fine-tuning type argument, but incredibly he cites cases where membranes can exist in widely varying temperatures. Like I say, it doesn't make much sense. And of course, it suffers the same problem as all fine-tuning arguments: is the evironment fine-tuned for life, or is life fine-tuned for the environment? Obviously, one expects living things to be adapted for the enivronment that they're found in, otherwise they wouldn't be there. And then there's the usual fallacy of ID thinking: we don't know off-hand of a natural process, therefore a space Goddidit. God of the Gaps, but with very tiny gaps. I would suggest just looking through PubMed on cell membrane evolution and Fox's protocells. Hit 'em up with that -- they've probably never seen this kind of research, which is typical. Oh yeah, the bit about the seasons is really stupid. People who live at the equator, where most life is found, don't experience seasons like we do. theyeti

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