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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.
Nowadays it seems like almost everything is twisting to the right...
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Nope. A helix has an intrinsic twist direction invariant from the point of view.
Check it yourself. Get two identical springs and put them side by side, flip one and voila you have the same configuration than before.
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?
I am lefthanded and mine twists to the right - my theory is it will usually point opposite of your prefered hand and my reason is furious masturbation.
Depending on how you define "life", yes. In fact, almost certainly, regardless of which definition of "life" you choose. Selection can occur in any kind of chemical or physical process in which produces similar but not always identical results. There's nothing special about the particular chemical processes we call "life", nor some magic line in the sand you can draw and say "this is life, and this isn't" -- it gets rather fuzzy on the edges, and the distinction between life and other chemical processes is as arbitrary as the distinction between which celestial bodies we decide to call "planets" and which we decide don't qualify. Nature doesn't care much for our arbitrary distinctions.
"Convictions are more dangerous enemies of truth than lies."
Because there is a right way
TFA mentioned several possible scenario - spin-polarized electrons, circularly polarized light that is produced by the scattering of light in the atmosphere and in neutron stars, and so on - which should have been taking place in similar fashion all throughout the universe
Would this mean that if there are lifeforms elsewhere in the universe, would their physiology (whether or not they have DNA) be similarly affected by the polarized action of electron and/or photon around them?
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Evolution happens as soon as you have a simple molecule that can replicate itself, or at least catalyse some reaction that leads to more copies of itself. If your definition of life does not include self-replicating molecules, then there was evolution before life.
Oh yeah? We'll soon see about -
Hmm. Maybe one of these is broken. I'm getting more springs.
systemd is Roko's Basilisk.
If it bent to the left, that'd be a bit...sinister.
Chas - The one, the only.
THANK GOD!!!
Actually, it's not. If your body tried to minimize its entropy, you'd end up frozen or your body separated into its constituent atoms.
I guess you're trying to describe the concept of homeostasis, which is in fact part of the "official" definition of life. One thing living things do is use energy to keep their internal state constant even against outside influences. This is different from trying to minimize entropy.
my reason is furious masturbation
While there's something to be said for angry make-up sex, maybe you ought to calm down a bit before taking care of business. You could hurt yourself, lad.
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.
Blasphemy is a human right. Blasphemophobia kills.
Why "right-handed"? Shouldn't it be "clockwise"?
Twisting towards the right hand could be "over the top" (clockwise) or "around the bottom" (counterclockwise). Not to mention that unless you specify whether you're twisting down the strand towards or away from you (assuming the strands are pointed straight away from your body), means you end up with 4 ways to arrive at 2 possible orientations.
I suppose the scientific response is, "No, shut up; we just defined this confusing and nonstandard wording as X."
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As someone else posted above, if you look at it from the opposite direction, it still twists right.
Find the nearest screw or bolt (almost all will be right-handed), pick an end to be up, point your right thumb in that direction then curl your fingers: your fingers will curl in the same direction that is needed to move up the spiral. Now flip the bolt or screw upside down and try it again... Yep, still works. Now try it with your left hand: your fingers will curl in the downwards direction. That is what is meant by right-handed or left-handed.