Posts Tagged ‘Chirality

Chirality Through Classical Physics

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Chris L. Lin
Chirality, or handedness, is a topic that is common in biology and chemistry, yet is rarely discussed in physics courses. We provide a way of introducing the topic in classical physics, and demonstrate the merits of its inclusion – such as a simple way to visually introduce the concept of symmetries in physical law – along with giving some simple proofs using only basic matrix operations, thereby avoiding the full formalism of the three-dimensional point group.
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Written by physicsgg

April 20, 2020 at 8:03 am

Posted in PHYSICS

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Supernovae, Neutrinos, and the Chirality of the Amino Acids

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Abstract: A mechanism for creating an enantioenrichment in the amino acids, the building blocks of the proteins, that involves global selection of one handedness by interactions between the amino acids and neutrinos from core-collapse supernovae is described.
The chiral selection involves the dependence of the interaction cross sections on the orientations of the spins of the neutrinos and the 14N nuclei in the amino acids, or in precursor molecules, which in turn couple to the molecular chirality. It also requires an asymmetric distribution of neutrinos emitted from the supernova.
The subsequent chemical evolution and galactic mixing would ultimately populate the Galaxy with the selected species.
The resulting amino acids could either be the source thereof on Earth, or could have triggered the chirality that was ultimately achieved for Earth’s proteinaceous amino acids (…..)

Part of the Veil Nebula (or NGC6960). The Veil Nebula is a faint remnant of a supernova that exploded some 5,000 years ago

If this model turns out to be correct, the longstanding question of how the organic molecules necessary to create and sustain life on Earth were created will have undergone a strong suggestion that the processes of the cosmos played a major role in establishing the molecules of life on Earth, either directly, or by providing the seeds that ultimately produced homochirality in the amino acids.
These molecules would appear to have been created in the molecular clouds of the galaxy, with their enantiomerism determined by supernovae, and subsequently either transported to Earth only in meteorites, swept up as the Earth passed through molecular clouds, or included in the mixture that formed Earth when the planets were created.
Any scenario in which these molecules were created exclusively on Earth in Darwin’s “warm little pond”, and supported by the experiment of Ref. [77], would find it much more difficult to explain the enantiomerism that is observed on Earth and, apparently, generally in the cosmos.
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Written by physicsgg

June 25, 2011 at 7:48 am