Update on Arsenic based life form:

Originally posted by sonhouse
Not understanding that one. If you look at the N2 or N singlet, how is it different if it is in isolation or if it is bound to some molecule? Is there an isotopic difference here? I would think the addition of a neutron or two wouldn't effect the chemical bonds.

I don't understand your post.

Phosphorus has chemical properties nitrogen does not because 1) it's physically larger and more important 2) it has a d-orbital available, which nitrogen does not. This allows it to make more chemical bonds and make a variety of molecules made up of only P. Nitrogen cannot do this. Pure nitrogen can only make N2.

Originally posted by AThousandYoung
I don't understand your post.

Phosphorus has chemical properties nitrogen does not because 1) it's physically larger and more important 2) it has a d-orbital available, which nitrogen does not. This allows it to make more chemical bonds and make a variety of molecules made up of only P. Nitrogen cannot do this. Pure nitrogen can only make N2.

http://www.angelfire.com/wv/jeanwilson/dna.html

In this little blub they clearly state Nitrogen as being part and parcel of the internal chemistry of DNA. How can that be if N can only bond to N?

Originally posted by sonhouse
http://www.angelfire.com/wv/jeanwilson/dna.html

In this little blub they clearly state Nitrogen as being part and parcel of the internal chemistry of DNA. How can that be if N can only bond to N?

Nobody claimed that. Do pay attention at the back.

Nitrogen is generally more limited in its bonding properties, and thus inherently more stable, than both phosphorus and arsenic. The fact that the only stable configuration of nitrogen itself is N2, while both phosphorus and arsenic have several options available, is an illustration of this fact. Nobody claimed that nitrogen can bond to nothing else; what was claimed is that nitrogen, when it bonds to anything including itself, is more limited in its options than the other two. (This also means that configurations with N in it are more stable, and thus more likely to survive and to be found in nature in large quantities, than ones with P and As in them. As is indeed the case.)

Richard

Originally posted by Shallow Blue
Nobody claimed that. Do pay attention at the back.

Nitrogen is generally more limited in its bonding properties, and thus inherently more stable, than both phosphorus and arsenic. The fact that the only stable configuration of nitrogen itself is N2, while both phosphorus and arsenic have several options available, is an illustration of this fa ...[text shortened]... nature in large quantities, than ones with P and As in them. As is indeed the case.)

Richard

Thanks for clearing that up. I wasn't sure why there was this talk about N being only stable with itself. So it is a plus it is more stable in DNA. Maybe that is why DNA and its relatives have survived for billions of years. Or a billion anyway.

Originally posted by sonhouse
http://www.physorg.com/news/2010-12-nasa-discovery-element-life.html

One amazing thing about this, it was predicted to be possible in a paper written over a year ago! I have a feeling their scientific stock is on the rise!

Also, does anyone here know if Sb (Antimony) is close enough chemically to also sub for phos in DNA and the like? Sb is the next one down that line on the periodic table.

It seems that the euphoria about the arsenic life-form has been premature. A significant load of criticism has been fallen on Wolfe-Simon and her team. It might still be true, but the neglect of NASA to put any of this criticism on their website is suspicious.
See Criticism at
http://en.wikipedia.org/wiki/GFAJ-1

Originally posted by TitusvE
It seems that the euphoria about the arsenic life-form has been premature. A significant load of criticism has been fallen on Wolfe-Simon and her team. It might still be true, but the neglect of NASA to put any of this criticism on their website is suspicious.
See Criticism at
http://en.wikipedia.org/wiki/GFAJ-1

So far it is just criticism. They have not proven NASA wrong, only given possible scenarios in which contamination may have been part of the original experiments. News at 11.

Originally posted by sonhouse
So far it is just criticism. They have not proven NASA wrong, only given possible scenarios in which contamination may have been part of the original experiments. News at 11.

It is not just criticism, but very fundamental criticism. The Simon-Wolfe team have omitted some trivial tests because "their was too little time". It seems they wanted to score rather than finishing a solid proof. The referees should have demanded these tests, but unfortunately they didn't. This has as a result that everybody is speaking about a finding that might be nothing special in the end. In other words, the proof that there is now is unsubstantiated and this hype should be viewed as a "no" until proven otherwise. NASA should prove they are true in the first place instead of relying on other research teams to clean up the garbage.

Originally posted by TitusvE
It is not just criticism, but very fundamental criticism. The Simon-Wolfe team have omitted some trivial tests because "their was too little time". It seems they wanted to score rather than finishing a solid proof. The referees should have demanded these tests, but unfortunately they didn't. This has as a result that everybody is speaking about a finding tha ...[text shortened]... true in the first place instead of relying on other research teams to clean up the garbage.

Le's clear it up a little. Can you summarize the problems for the genral public in layterms, please.

Are these bacteria using Arsenic instead of Phosphor or not?

If yes: Are every Phosphor atom swapped with an Arsenic, or just some.
And if so: Are there particular places where Arsenic are used, or are they here and there at random?

If no: What did they do wrong, where did they do the mistake? Aren't there any interesting things left or it is just a hen out of a feather?

Originally posted by FabianFnas
Can you summarize the problems for the genral public in layterms, please.

This was already done by science writer Carl Zimmer for Slate:
http://www.slate.com/id/2276919/

On his blog, Zimmer has published the original statements of the scientists he asked about this paper:
http://blogs.discovermagazine.com/loom/2010/12/08/of-arsenic-and-aliens-what-the-critics-said/

Originally posted by Zaubernuss
This was already done by science writer Carl Zimmer for Slate:
http://www.slate.com/id/2276919/

On his blog, Zimmer has published the original statements of the scientists he asked about this paper:
http://blogs.discovermagazine.com/loom/2010/12/08/of-arsenic-and-aliens-what-the-critics-said/

Well, blogs... Tell me one opinion not found in a blog?

Originally posted by FabianFnas
Well, blogs... Tell me one opinion not found in a blog?

Well, I have no reason to doubt the blog author's claim that he included in that post every answer he got to his requests for commentary on the paper. So we get a representative sample of opinions about the paper from scientists working in relevant fields.
What more could you expect?

From what I understood there are several criticisms. Some scientist do not even believe that NASA found arsenic in the DNA. This can be tested with special mass-spectrometry but the equipment was not available and "there was no time". The only thing that they found was that the bacteria could live and grow in a phosphor-poor and arsenic-rich environment. But this little bit of phosphorus might be enough. Other scientist object that they bred the bacteria in the lab. They did not report on the fresh bacteria that was found in the Mono-lake. The bacteria was fed slowly with more and more arsenic after it was fished out of the lake and bred in the lab. If arsenic was really incorporated in the DNA it is nothing more than a curiosity. It has nothing to do to the natural behavior of the bacteria or with a new kind of genetic transcription. Also other organisms sometimes build in strange elements in their system if they have to. Snails sometime exchange iron for copper in their blood. I am not a specialist in this field myself, but tend to believe the critics. Extraordinary claims require extraordinary facts and NASA failed to give them.

Originally posted by TitusvE
I am not a specialist in this field myself, but tend to believe the critics. Extraordinary claims require extraordinary facts and NASA failed to give them.

I'm not either - but I will say that its a rare scientific finding that isn't challenged or has all of the facts on the first publication. That's part of the scientific process. Criticism doesn't make the hypothesis wrong. I think it's hard to "believe" either side until there's more evidence.

Originally posted by joneschr
I'm not either - but I will say that its a rare scientific finding that isn't challenged or has all of the facts on the first publication. That's part of the scientific process. Criticism doesn't make the hypothesis wrong. I think it's hard to "believe" either side until there's more evidence.

True. But I am a scientist in another field and I have seen this scenario several times. Sloppy inaccurate work often generates spectacular results that disappear when the research is redone very solidly. In such cases it is better to disbelieve until proven otherwise.

Originally posted by TitusvE
True. But I am a scientist in another field and I have seen this scenario several times. Sloppy inaccurate work often generates spectacular results that disappear when the research is redone very solidly. In such cases it is better to disbelieve until proven otherwise.

What is your field? Are you through with thesis and such?