NASA Researchers Discover the Origin of a Major Aspect of Creation of Life

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Talk about way over my head here.
But if what they find here is true.
Then that means that finding microbial life on different planets just got harder.

Researchers analyzing meteorite fragments that fell on a frozen lake in Canada have developed an explanation for the origin of life's "handedness" – why living things only use molecules with specific orientations. The work also gave the strongest evidence to date that liquid water inside an asteroid leads to a strong preference of left-handed over right-handed forms of some common protein amino acids in meteorites. The result makes the search for extraterrestrial life more challenging.
"Our analysis of the amino acids in meteorite fragments from Tagish Lake gave us one possible explanation for why all known life uses only left-handed versions of amino acids to build proteins," said Dr. Daniel Glavin of NASA's Goddard Space Flight Center in Greenbelt, Md. Glavin is lead author of a paper on this research to be published in the journal Meteoritics and Planetary Science.

reply to post by grey580


That was the one thing about organic chemistry that I could never could grok.... 2 substances, exactly the same chemical formula, but the one is left-handed and the other right handed. The one is deadly, and the other one is beneficial. I think my organic chemistry professor got 1000 more grey hairs trying to explain it to me, before giving up. I managed to pass that module, but today, 30 years later, I still can't grasp it ....

Still hoping that one day I'll meet a chemist that can explain it to me in a way I would understand AND remember.

reply to post by Hellhound604


Basically, to strip it all down to ultra-basics, let's say your cell has two different kinds of receptors. One says "Build more of that enzyme" and the other says "You have miscopied your genes and should kill yourself, little cell". Now imagine that they are similar to left and right gloves and left and right hands being the different stereoisomers involved. If you send the wrong signal, you get the wrong effect.

And the glove analogy is remarkably apt as those kinds of binding/unbinding sites are often VERY much based on shape in 3 dimensions. And, topologically, a left-handed spiral is a _fundamentally_ different shape than a right-handed one.

Originally posted by Stunspot
reply to post by Hellhound604

 

Basically, to strip it all down to ultra-basics, let's say your cell has two different kinds of receptors. One says "Build more of that enzyme" and the other says "You have miscopied your genes and should kill yourself, little cell". Now imagine that they are similar to left and right gloves and left and right hands being the different stereoisomers involved. If you send the wrong signal, you get the wrong effect.

And the glove analogy is remarkably apt as those kinds of binding/unbinding sites are often VERY much based on shape in 3 dimensions. And, topologically, a left-handed spiral is a _fundamentally_ different shape than a right-handed one.

True, that is what my lecturers tried to teach me. But when I see those 3-D models when they tried to explain it to me, I could just rotate them in my mind, and they would slot right in..... I guess I missed some fundamental issue somewhere, or my brain is just wired wrong. Maybe that is the reason why I never went further into organic chemistry, no matter how interesting it was, I could never grasp one of the most fundamental aspects of it.....

Originally posted by Hellhound604
True, that is what my lecturers tried to teach me. But when I see those 3-D models when they tried to explain it to me, I could just rotate them in my mind, and they would slot right in..... I guess I missed some fundamental issue somewhere, or my brain is just wired wrong. Maybe that is the reason why I never went further into organic chemistry, no matter how interesting it was, I could never grasp one of the most fundamental aspects of it.....

"just rotate"
You make a very good point.

reply to post by grey580


I've looked into this some time ago and it also deals with the protection it provides from solar radiation.

Originally posted by Hellhound604
True, that is what my lecturers tried to teach me. But when I see those 3-D models when they tried to explain it to me, I could just rotate them in my mind, and they would slot right in..... I guess I missed some fundamental issue somewhere, or my brain is just wired wrong. Maybe that is the reason why I never went further into organic chemistry, no matter how interesting it was, I could never grasp one of the most fundamental aspects of it.....

The point is that you can't rotate them. Take for example a spiral staircase. Even if you turn it upside down, the spiral still rotates around the axis from the same side..

reply to post by rhinoceros


I believe I am starting to see the light. Not sure why I couldn't see it many years ago. I had a brainwave last night to build some 3D molecular models of chiral compounds, and all of a sudden it just became visible. I should have sat in class building 3D models, but I guess my fellow students would have looked at me as though I was mad.

So do I have it right, in an achiral molecule, the mirror image is the same, but in a chiral molecule, it is not the same.
In a chiral molecule, if I see the mirror image, the one part of the molecule will point in instead of out. (sorry, I don't have the correct terminology, but I don't have my organic chemistry textbooks at hand.)

You guys are wonderful!!!!!

I passed organic chemistry and biochemistry in a way I hated, by memorizing things, because I couldn't understand it. For me that was always the wrong way. To enjoy a subject, you must grok it, not memorize it.