Re: A cool theory of abiogenesis


"J.A.Legris" <jalegris@xxxxxxxxxxxx> wrote in message news:fnqeoq$1t88$1@xxxxxxxxxxxxxxxxxxxxxx
On Jan 29, 1:48 pm, dkomo <dkomo...@xxxxxxxxxxx> wrote:
Did Life Begin in Ice?

February 20008 issue of "Discover" magazine

"One morning in late 1997, Stanley Miller lifted a glass vial from a
cold, bubbling vat. For 25 years he had tended the vial as though it
were an exotic orchid, checking it daily, adding a few pellets of dry
ice as needed to keep it at -108 degrees Farenheit. He had told hardly
a soul about it. Now he set the frozen time capsule out to thaw, ending
the experiment that had lasted more than one-third of his 68 years."

The vial contained cyanide and ammonia. When Miller and his former
student Jeffrey analyzed the contents, they found it contained
nucleotides and amino acids.

Who'd have thunk it?

Not me. I'm reasonably certain the mix contained nucleic acid bases
such as adenine rather than nucleotides such as adenosine.

The theory is that small amounts of liquid persists even at sixty below
(Fahrenheit) and simple molecules could have assembled into longer
chains. To the doubters, the article states: ..."strange things happen
when you freeze chemicals in ice. Some reactions slow down, but others
actually speed up -- especially reactions that involve joining small
molecules into larger ones .. by a process called eutectic freezing. As
an ice crystal forms, it stays pure: Only molecules of water join the
growing crystal, while impurities like salt or cyanide are excluded.
These impurities become crowded in microscopic pockets ... caus[ing] the
molecules to collide more often. Chemically speaking, it transforms a
tepid seventh-grade school dance into a raging molecular mosh pit."

Normally chemical reaction rates slow down as temperature falls, but
eutectic freezing can create liquid pockets of highly concentrated
chemicals, and reaction rates *increase* when concentrations increase,
more than compensating for the slowdown.

Other cool facts in the article:

1. After the rain of asteroids stopped after the earth was born, the
earth may have become a giant snowball with an average surface
temperature of -40 degrees F because at that time the sun was 30 percent
dimmer than it is now. The earth may have had a crust of ice 1000 feet
thick covering the oceans.

2. RNA enzymes that normally snip other RNA molecules into pieces can
reverse their action when cooled to low temperatures and can begin
joining short RNA fragments together.

A truly awful journalistic description of what happens to those enzymes
and reactions at low temperatures.

3. Small pockets of water trapped within sea ice can remain liquid down
to temperatures of -60 degrees F, and bacteria and diatoms can inhabit
those pockets. Films of water on the surfaces of some minerals can
remain liquid down to -90 degrees F.

4. Jupiter's moon Europa has a layer of thick ice on top of an ocean of
liquid water. The temperatures within that ice, and lower down in the
ocean water are within the temperature ranges discussed above.

Unfortunately the Discover article is not online, but here's an older,
shorter article with the same title:

Did life begin in ice?http://www.world-science.net/exclusives/050809_icefrm.htm

--dk...@xxxxxxxx

Here's another link:

http://www.springerlink.com/content/lbyy4hec4qgxu7dw/

Thx. Unfortunately I don't have a subscription. But I'm curious.

According to the abstract, they say that due to hydrolysis of
HCN, the steady state ocean concentration would not rise
above about 10^-12 M. I wonder whether this includes the
HCN which is in the form of ligands for dissolved transition
metals. I would think that ligated HCN would be relatively
well protected from hydrolysis.

Similarly, it would seem to me that if there are significant
amounts of HCN (and CO) available in the "soup" ligated
to transition metals, then you wouldn't need eutectic freezing
to create high local concentrations of HCN. Simple freezing
accompanied by precipitation of metal carbonates and phosphates
should be enough to leave high HCN concentrations in the
remaining liquid.

Comments from people who understand the chemistry better
than me are very welcome. Does the article even mention
transition metals?

.

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