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Author Topic:   RAZD - Building Blocks of Life
Matt P
Member (Idle past 3524 days)
Posts: 106
From: Tampa FL
Joined: 03-18-2005


Message 15 of 30 (270088)
12-16-2005 3:19 PM
Reply to: Message 2 by RAZD
12-03-2005 9:03 PM


Re: text translation issue?
Hi RAZD! I think you have a great summary here. I'd like to add/clarify a few small things, as well as give a bit of info about where the current state of the field is.

Traditionally chemists have referred to these compounds as organic molecules because of their association with organic processes. With these discoveries of such molecules in outer space and, presumably, from non-living sources, it seems that a new paradigm is needed. I will refer to these cosmic based complex hydro-carbon compounds hereafter as "Pre-Organic Compounds", or POCs.

Generally, "organic" refers to molecules containing carbon and usually hydrogen. Most carbon-containing compounds are organic compounds, the main exceptions are carbonates and carbides, both of which are minerals. The root for the word "organic" is indeed linked to life, however most researchers in the field refer to these compounds as "abiotic" or "prebiotic" compounds. Nothing big, just word choice.

Moving farther in, we have detected a host of POCs on meteors.

Again, word choice. "Meteors" specifically refers to a body entering the Earth's atmosphere prior to landing. Detecting organics in meteors is possible, but very difficult given their stochastic nature. "Meteorites" is the proper term, and is definitely what Dr. Pizarello studies.

While early models of the earth assumed an acidic atmosphere, recent modeling of the Earth's early atmosphere suggests more neutral conditions (e.g. CO2, N2, H2O) may have existed (15 Ehrenfreund et al 2002).

Again, word choice. Early models have assumed a "reducing" atmosphere, as opposed to our current oxidizing atmosphere (with O2)

the oldest evidence for life may be thermophile remnants in Greenland rocks that are 3.7 to 3.9 billion years old, where some researchers have concluded that the grains contained carbon of biological origin (23 Hart 2005).

Unfortunately, this line of evidence has been pretty much dismissed, even by the individuals who first proposed it. Try going here:
http://ebpi.arc.nasa.gov/agenda/agenda_wednesday.htm
and click on the presentation at 3:20, next to Arrhenius. Essentially, the graphite found in the carbon was too crystalline to have a biologic origin. However, this just pushes the origin back to 3.5 Ga, where we have less controversial evidence for life.

All in all, I think you have a great article here, and I hope the info above helps a bit.


This message is a reply to:
 Message 2 by RAZD, posted 12-03-2005 9:03 PM RAZD has responded

Replies to this message:
 Message 16 by RAZD, posted 12-17-2005 9:59 PM Matt P has not yet responded
 Message 20 by RAZD, posted 12-18-2005 10:38 PM Matt P has responded

  
Matt P
Member (Idle past 3524 days)
Posts: 106
From: Tampa FL
Joined: 03-18-2005


Message 21 of 30 (270887)
12-19-2005 5:47 PM
Reply to: Message 20 by RAZD
12-18-2005 10:38 PM


Re: text translation issue?
Hi RAZD, looks great! Also, if you want another reference for the phosphorus work instead of Reddy 2004, you can cite:
Pasek, M.A., and Lauretta, D.S., 2005, Astrobiology 5(4), 515-535. Let me know if you would like a copy of this article as a .pdf.

Again, great job!


This message is a reply to:
 Message 20 by RAZD, posted 12-18-2005 10:38 PM RAZD has responded

Replies to this message:
 Message 23 by RAZD, posted 12-22-2005 6:33 PM Matt P has not yet responded

  
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