Theoretical origin of life; Chirality of space molecules (Introduction)

by David Turell , Thursday, August 18, 2016, 00:13 (3023 days ago) @ David Turell

A molecule has been identified in space with chirality, which means left or right handed configuration. In this case the handedness is not identified, but the article waxes excitedly about the relationship to origin of life. to remind everyone, amino acids in life are all left handed, and the DNA and RNA sugar molecules, ribose, are all right handed:
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> https://www.sciencedaily.com/releases/2016/06/160614142127.htm
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> "Scientists applaud the first detection of a "handed" molecule, (propylene oxide) in interstellar space. It was detected, primarily with the NSF's Green Bank Telescope, near the center of our Galaxy in Sagittarius (Sgr) B2, a massive star-forming region. Propylene oxide is one of a class of so-called "chiral" molecules -- molecules that have an identical chemical composition, but right- and left-handed versions. Chiral molecules are essential for life and their discovery in deep space may help scientists understand why life on Earth relies on a certain handedness to perform key biological functions." 
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> Comment: No one has any idea why handedness is so specific in life, and this fonding won't help explain it. Studies on living matter might.
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> ""This is the first molecule detected in interstellar space that has the property of chirality, making it a pioneering leap forward in our understanding of how prebiotic molecules are made in the Universe and the effects they may have on the origins of life," said Brett McGuire, a chemist" 
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> Comment: Not true. Amino acids have handedness and are found on meteorites from space.
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> "Complex organic molecules form in interstellar clouds like Sgr B2 in several ways. The most basic pathway is through gas-phase chemistry, in which particles collide and merge to produce ever more complex molecules. Once organic compounds as large as methanol (CH3OH) are produced, however, this process becomes much less efficient.
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> "To form more complex molecules, like propylene oxide, astronomers believe thin mantles of ice on dust grains help link small molecules into longer and larger structures. These molecules can then evaporate from the surface of the grains and further react in the gas of the surrounding cloud.
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> "To date, more than 180 molecules have been detected in space. Each molecule, as it naturally tumbles and vibrates in the near vacuum of the interstellar medium, gives off a distinctive signature, a series of telltale spikes that appear in the radio spectrum. Larger and more complex molecules have a correspondingly more complex signature, making them harder to detect."
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> Comment: Just because some of life's molecules exist in space, it doesn't mean they will spontaneously assemble on Earth's surface.
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> "'Meteorites in our Solar System contain chiral molecules that predate the Earth itself, and chiral molecules have recently been discovered in comets," noted Carroll. "Such small bodies may be what pushed life to the handedness we see today."
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> "'By discovering a chiral molecule in space, we finally have a way to study where and how these molecules form before they find their way into meteorites and comets, and to understand the role they play in the origins of homochirality and life," McGuire said.'
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> Comment: The amino acids in meteorites are 53% left handed and 47% right handed according to recent reports. In life 100% left. Not much help there. Hope springs eternal that God is not required.-Another take on the same discovery:-http://www.scientificamerican.com/article/astrochemists-detect-chiral-molecules-in-interstellar-space-for-the-first-time/?WT.mc_id=SA_DD_20160817-"Life seems to prefer molecules of a single chemical handedness, however. All DNA, for example, twists clockwise like the threads on a right-handed screw. Nearly all amino acids, meanwhile, are left-handed. Why one or the other? “It's pretty well established that once an excess [of one chirality] is present, life is going to go with it,” says Brett McGuire, an astrochemist at the National Radio Astronomy Observatory in Charlottesville, Va."-Comment: this comment is wild speculation, not supported by the general literature re' chirality. Uncontrolled a reaction makes roughly right and left molecules equally:-"Others are skeptical. Arizona State University biochemist Sandra Pizzarello, who has studied chiral molecules in meteorites, says connecting the observations to DNA chirality could be difficult. “We are still left wondering what happens” on the long path between molecular clouds and the origins of life, she says."