Physicists Find Clue as To Why the DNA Double Helix Twists To the Right

New submitter Annanag writes Most organic molecules have left- or right-handed versions, mirror images of each other, just like gloves. For some reason, life always seems to favor one version over the other — the DNA double helix in its standard form always twists like a right-handed screw, for example. But why this preference for left or right happens has always been a mystery. Now, in an experiment that took 13 years to perfect, physicists have found hints that this asymmetry of life could have been caused by electrons from nuclear decay in the early days of evolution.

Comments

Random chance more likely

[Anonymous Coward]

Mutations happen randomly. A mutation occurs in Right-Version that's beneficial and so the right version becomes the dominant version, nothing to do with right or left, its simply the version that got the beneficial mutation.

So evolution would drive nature to choose left or right versions of every little enzyme, molecule and so on, simply because it grows from benefitial branches and they are either left or right but not an even mix of both.

alternative selective force than early-universe el

[elleard]

They forgot a simpler and perhaps more prominent selective force for one enantiomer over another: average experienced twist on the earliest nucleic acid chains from ocean currents. It should be slightly one way, due to Coriolis forces. Did life start North or South of the equator?

Asimov said it first

[Ateocinico]

http://en.wikipedia.org/wiki/T...

Headline: "Force of nature gave life its asymmetry

[radtea]

Article:

The interaction of left-handed electrons with organic molecules is not the only potential explanation for the chiral asymmetry of life.. Meierhenrich favours an alternative â" the circularly polarized light that is produced by the scattering of light in the atmosphere and in neutron stars3. In 2011, Meierhenrich and colleages showed4 that such light could transfer its handedness to amino acids.

But even demonstrating how a common physical phenomenon would have favoured left-handed amino acids over right-handed ones would not tell us that this was how life evolved, adds Laurence Barron, a chemist at the University of Glasgow, UK. âoeThere are no clinchers. We may never know.â

The new work is interesting and important, but its primary significance is that it makes future work distinguishing the possible alternatives more challenging. It's also interesting because unlike the other two proposed mechanisms it is a result of the fundamental asymmetry in the weak force rather than an accidental boundary condition, so it implies that life everywhere is more likely than not to be right-handed, whereas the explanations involving magnetic fields will make a universe that's 50/50 right/left.