Posted on 03/01/2008 3:02:36 PM PST by blam
That’s handy
Put your hand in the hand of the man that stilled the waters.
Put your hand in the hand of the man that stilled the waters.
There are some who believe that life here began out there . . .
L. Ron Hubbard?
We are interested in the origin of biomolecular chirality. Dr Alexandra MacDermott - It is well known that biomolecules are all of one hand, but what determines which hand? Why are animals made of L-amino acids and not D-amino acids? This asymmetry in biology may be a feature of fundamental physics, because it turns out that the "natural" L-amino acids are slightly more stable than their "unnatural" D mirror images, due to the weak force. The weak force, carried by the Z boson recently discovered at CERN, is one of the four forces of nature - electromagnetic, weak, strong and gravity - and it is the only one of the four which can tell the difference between left and right. Due to the weak force, L and D molecules have slightly unequal energies because they are not in fact true mirror images: the true enantiomer of an L-amino acid is the D-amino acid made of anti-matter. We calculate these small energy differences between enantiomers using ab initiomolecular orbital methods. In most cases our calculations do indeed predict the correct sign: not only are the L-amino acids more stable than the D, but the natural D-sugars are more stable than the L, and the right-hand DNA double helix is also more stable than its left-hand mirror image. We believe the slight enantiomeric excess from these "parity-violating energy differences" could be amplified kinetically in the pre-biotic soup to preferentially select today's L-amino acid/D-sugar biochemistry over D-amino acid/L-sugar "mirror life". The parity-violating energy difference between enantiomers is not the only way in which the weak force could select biomolecular chirality. Radioactive beta decay is mediated by the weak force, and this causes a polarization of the electrons emitted in beta decay, which could produce selective destruction of one enantiomer. We are currently starting to develop the theory of this enantioselective beta-radiolysis. Chirality is a characteristic signature of life, and we are collaborating with experimentalists and space engineers to develop a small polarimeter to detect optical rotation as the signature of life on Mars. We also hope to detect the chiral signature of life using polarimetry on the future Darwin space telescopes which will catch light from planets around otherstars: light from an Earth-like planet will show a small circular polarization due to the highly chiral chlorophyll molecules in vegetation cover. Finding molecules of the same hand on many different extra-solar planets would lend support to the weak force theory of the origin of chirality. Some of our team are Co-Investigators on the COSAC experiment of the Rosetta mission, launch 2003, which will use chiral gas chromatography to identify enantiomeric excesses on Comet Wirtanen. We are collaborating with Glaxo Wellcome to use chiroptically detected HPLC to identify chiral molecules in the Murchison and Mars meteorites.
Used to be we’d look up our family tree and get hit by monkey poo. Now we look up and get hit by a meteorite?
Battlestar Galactica
the original series
I worked with Pizzarello’s husband at Honeywell Bull. We had Sandra and her husband over for dinner several years ago. He cooked and did it very well. Tony described her work as “cooking rocks”.
Could be. Something does.
In the words of a physician I once knew: “A universal law is that stool gets everywhere.”
And while he was talking about routine contamination, he was also correct that it is a universal situation. Or at least, from our point of view, a galactic one.
That is, in our galaxy, there are truly vast distances between planetary bodies. But these distances can be reduced by having a lot of time to travel between such bodies. For example, the nearest star to our own is Alpha Centauri, just down the block from Sol at about 4 light years distance.
Since physical objects can’t travel that fast, at least normally, even if it was zipping right along, say at 36,000 miles an hour, it would still take about 150,000 years just to get from there to here.
However, The Milky Way galaxy may be 8 billion or more years old. Its oldest star is estimated to be around 13 billion years old.
So if time is no object, a lot of “stool”, or space junk, can get circulated around the galaxy at a leisurely pace.
This is important, if you consider that during the lifetime of Earth, a mere 4.5 billion years, only a tiny fraction of that time has had life here, of any kind. Life was almost wiped out many times.
However, while Earth was teeming with life, had another major object struck it, blasting pieces of Earth into space, while the life would not have survived, its component organizational blocks, such as amino acids, might have traveled vast distances to perhaps encounter another planetary body.
And other planets organizational structures might have done the same to Earth.
Or as the doctor said, “Stool gets everywhere.”
Hmmm. Small world. Or at least small degrees of seperation sometimes. My son got his PhD at ASU.
Do what? We already know that the preponderance of laevorotary amino acids from Murchison are due to contamination from terrestrial sources, likely when the thing came smashing its way into our planet’s surface.
Proxima Centauri, actually, is slightly closer.
YEC INTREP
ASU??? Didn’t even know they could read at Tempe normal.
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