Cosmic Rays and Left-Handed DNA

[Recusant]

Sorry, this isn't about human southpaws. Instead, it's about chirality (loosely, "left-handedness and right-handedness") in molecules.

The molecules that are integral to life show definite chirality. Amino acids that Earth organisms use are right-handed. The DNA molecule of life on Earth is left-handed. There has been no confirmed explanation for this phenomena. A new paper proposes that it is the result of the effect of cosmic rays on the beginnings of life. 

"Cosmic rays may have left indelible imprint on early life, Stanford physicist says" | Stanford News

Before there were animals, bacteria or even DNA on Earth, self-replicating molecules were slowly evolving their way from simple matter to life beneath a constant shower of energetic particles from space.

In a new paper, a Stanford professor and a former postdoctoral scholar speculate that this interaction between ancient proto-organisms and cosmic rays may be responsible for a crucial structural preference, called chirality, in biological molecules. If their idea is correct, it suggests that all life throughout the universe could share the same chiral preference.

Chirality, also known as handedness, is the existence of mirror-image versions of molecules. Like the left and right hand, two chiral forms of a single molecule reflect each other in shape but don't line up if stacked. In every major biomolecule – amino acids, DNA, RNA – life only uses one form of molecular handedness. If the mirror version of a molecule is substituted for the regular version within a biological system, the system will often malfunction or stop functioning entirely. In the case of DNA, a single wrong handed sugar would disrupt the stable helical structure of the molecule.

Louis Pasteur first discovered this biological homochirality in 1848. Since then, scientists have debated whether the handedness of life was driven by random chance or some unknown deterministic influence. Pasteur hypothesized that, if life is asymmetric, then it may be due to an asymmetry in the fundamental interactions of physics that exist throughout the cosmos.

"We propose that the biological handedness we witness now on Earth is due to evolution amidst magnetically polarized radiation, where a tiny difference in the mutation rate may have promoted the evolution of DNA-based life, rather than its mirror image," said Noémie Globus, lead author of the paper and a former Koret Fellow at the Kavli Institute for Particle Astrophysics and Cosmology (KIPAC).

In their paper, published on May 20 in Astrophysical Journal Letters, the researchers detail their argument in favor of cosmic rays as the origin of homochirality. They also discuss potential experiments to test their hypothesis.

[Continues . . .]

The paper is open access, and linked in the final paragraph above.

[Dark Lightning]

Cool!

[billy rubin]

a very sinister idea.

[Randy]

Cosmic rays are how the Fantastic Four got their super powers.

(Sorry, I couldn't resist. Actually, I could but didn't.)



Actually, that's an intriguing article. It could help explain more of the evolutionary process. I think it is an exciting find.

[Recusant]

It's cool.   

Really, the name tells you all you have to know. "Cosmic rays" just have to be some heavy stuff, with untold effects.   

[hermes2015]

Chirality and symmetry are fascinating parts of chemistry and great fun to teach.

[billy rubin]

chiral chiroptera:

The bats spiral out of the cave in a counter-clockwise direction. It is not known why they choose to spiral counter-clockwise, but current research suggest a variety of factors play roles. One of these may be an internal 'compass' in the bats that is based on the earth's magnetic poles.

this population prefers widdershins. other bats are apparently ambidextral

https://www.nps.gov/cave/learn/nature/bft_bat_outflight.htm

sorry about the wagner

[xSilverPhinx]

Perfect place to put this:

[hermes2015]

Perfect place to put this:

Does your nerdiness know no limits? 

[xSilverPhinx]

Perfect place to put this:

Does your nerdiness know no limits? 

If there is a limit I haven't found it yet. 

[hermes2015]

If there is a limit I haven't found it yet. 

Good.

"The road of excess leads to the palace of wisdom...You never know what is enough until you know what is more than enough."

― William Blake, Proverbs of Hell

[xSilverPhinx]

If there is a limit I haven't found it yet. 

Good.

"The road of excess leads to the palace of wisdom...You never know what is enough until you know what is more than enough."

― William Blake, Proverbs of Hell

I had to digest that quote for a moment before I knew it's totally true.

[Dark Lightning]

Well, if my DNA is left-hand spiral, why am I right-handed? Checkmate, biologists! 

Silver, I really like that Samuel Jackson pic! 

[xSilverPhinx]

Well, if my DNA is left-hand spiral, why am I right-handed? Checkmate, biologists! 

Silver, I really like that Samuel Jackson pic! 

If I taught chemistry in High School I would definitely use it!