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progenesПодготовительная литература к сегодняшнему анонсу NASA
"Аn astrobiology finding that will impact the search for evidence of extraterrestrial life":
Arsenic in the Evolution of Earth and Extraterrestrial Ecosystems
Ronald S. Oremland, Chad W. Saltikov, FelisaWolfe-Simon,and John F. Stolz
Судя по пышности анонса, будет что-то весьма спекулятивное.
"Аn astrobiology finding that will impact the search for evidence of extraterrestrial life":
Arsenic in the Evolution of Earth and Extraterrestrial Ecosystems
Ronald S. Oremland, Chad W. Saltikov, FelisaWolfe-Simon,and John F. Stolz
Судя по пышности анонса, будет что-то весьма спекулятивное.
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Date: 2010-12-02 04:08 pm (UTC)no subject
Date: 2010-12-02 04:09 pm (UTC)no subject
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Date: 2010-12-02 04:17 pm (UTC)no subject
Date: 2010-12-02 04:21 pm (UTC)The Group 15 elements above arsenic in the Periodic Table, namely nitrogen and phosphorous, play key roles in the biochemistry of life. Nitrogen is an essential structural element in binding together the myriads of carbon compounds found in the cell, its redox properties allow it to serve as an electron acceptor or donor, and its gaseous forms are agents of inter-cellular signaling.
Phosphorus, because of its stability in the +5 oxidation state (E0 = PO3−4 /PO3−3= −690 mV), took on the dual roles of molecular structural support (e.g., DNA) and as an energy currency. Arsenic, with the exception of a few organic arsenicals (e.g., arsenobetaine) became relegated to the poisonous “party spoiler” element. Yet, because arsenic is an analog of these two key elements, there has been speculation about the possibility of “undetected” life hiding in plain sight as it were, where As substitutes for P given known biological arsenic interactions
(Wolfe-Simon et al. 2009).
Such speculation has been around long enough that it has even spilt into the realm of science fiction literature (e.g., Slonczewski 2000). While As-structurally based life is tempting to think about, the bond lengths are only 10% greater for As vs.P and yet, they would break too easily (Dixon 1997), unless at extremely low temperatures, like on the outer planet/planetoids (B. Rosen, pers. comm.)
инопланетяне
Date: 2010-12-02 04:34 pm (UTC)no subject
Date: 2010-12-02 05:10 pm (UTC)no subject
Date: 2010-12-02 05:22 pm (UTC)no subject
Date: 2010-12-02 07:37 pm (UTC)эх, биологи...
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Date: 2010-12-02 08:06 pm (UTC)это не так интересно, как можно бы надеяться :( хотя конечно интересно.
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Date: 2010-12-02 08:11 pm (UTC)