Is this a mistake in the article? I was under the impression that all electrons are fundamentally identical to one another.
The weak nuclear force breaks chiral symmetry, so in beta decays--which are governed by the weak force--you tend to get neutrinos with their spin aligned with their direction of motion and electrons with their spin anti-aligned with their direction of motion, where "aligned" means if your right thumb is pointed in the direction of motion, the curling of your fingers gives the sense of rotation associated with the spin and "anti-aligned" is the same except that it's your left thumb pointing along the direction of motion.
In a system with strict chiral symmetry the two spins would always be opposed (which is required because angular momentum is conserved) but there would be no preference relative to each particle's direction of motion.
Can someone explain the mechanism behind the origin of that ribozyme from original RNA molecules?
The best example of chirality and toxicity is thalidomide. One isomer has low toxicity and the other causes horrible birth defects. Unfortunately the two isomers can interconvert so it isn't possible to create a pure sample of just one of them.
Oh, to create a pure sample is a trivial task. But unfortunately it racemizes in your body.
It is actually a very interesting compound. Would not be surprised about a come-back.
I am not 100% up to date in this area, but the last time I looked into the isomer theory of thalidomide toxicity it was not well supported by the experimental evidence.
Well actually, I suspect that it isn't arbitrary at all: historically, people have considered left-handed as deviant, strange, sinister, so obviously the good molecules are right-handed.
(Disclaimer: I'm a slightly bitter left-handed designer who has seen one too many "more intuitive" designs that are optimised for right-handedpeople)
An experimental setup to demonstrate this is a light source, a linear polarizer oriented in some direction (say along the x-axis for definiteness), followed by the sample container, followed by another linear polarizer, followed by a detector.
With nothing in the sample container, the second polarizer is rotated around the light beam axis until no light passes through. This will be very close to a right angle with the first one (try it with polarizing sunglasses :) ). The sample is then added, and the change in angle of the second polarizer required to again allow no light through is observed.
Rotating the spiral along it's axis changes nothing.
Rotating the spiral 180 deg around any axis perpendicular to its own, will not change the above.
Only when you reflect the spiral does it change handedness.
You can rotate the "left handed" version any way you want, but you won't be able to superimposed it on the "right handed" version.