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exponent137
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We know that DNA and other biological molecules have only one chiriality of two possible. Is here any explanation of this or any speculations about this?
Kevin McHugh said:I think it is much simpler than that. My pet theory is that homochirality stems from the intrinsic angular momentum of the Earth spinning on its axis. This angular momentum favored one chirality over the other in the primordial soup.
Kevin McHugh said:Perhaps the proto amino acids "felt" the angular momentum of rotation, and for that reason assumed the leverorotatory configuration as a result.
Drakkith said:Unless you have a reference that backs this up somehow then I'm afraid we can't discuss it. We don't allow personal theories here at PF.
exponent137 said:We know that DNA and other biological molecules have only one chiriality of two possible. Is here any explanation of this or any speculations about this?
The presence of carbon atoms with four chemically distinct substituents leads to chiral molecules, with non-superimposable mirror image forms known as stereoisomers. In any chemical synthesis, without intervention, an almost equal or racemic mixture of left- and right-handed molecules will form. So where did our homochiral world come from?
Donna Blackmond from the Scripps Research Institute in California, US, has been tackling the question. She says there is a rationale for why homochirality might offer a survival advantage. Chirality is important for creating complex systems with varied forms of molecular recognition and selectivity – both of which are crucial in life. Blackmond says when she gives talks to children, she uses a handshake to explain these concepts. ‘We shake hands and then I say “Let me try this with my left hand and your right hand” – and that doesn’t work very well. Left and right doesn’t make the same handshake or give the same message.’
Ygggdrasil said:Here's a nice news piece from the Royal Society of Chemistry on why homochirality is important: http://www.rsc.org/chemistryworld/2015/10/origin-homochirality-life-asymmetry
"Why is everyone’s DNA right-handed?’ asks Tim Gay from the University of Nebraska–Lincoln, US. Two theories have been proposed in answer to this question. The first idea is that homochirality came to Earth from space on the back of a comet..."
Kevin McHugh said:I looked for references, but apparently nobody knows exactly the angular velocity of the Earth 3.8 billion years ago when coacervates were forming in the primordial seas. The only thing we can say for sure, it was greater then than today. For certain, the day was 22 hours long in the precambrian, about 500 million years ago. If we can't discuss it so be it.
Bruzote said:We all like explanations, but we should remember what seems weird is sometimes what really should be expected. How could you NOT expect exclusive chirality from a single starting point of evolution when the complexity of life eventually demands chiral preference?
Drakkith said:Again, unless someone can find a reference that suggests a method by which homochirality is due to a fast-spinning Earth, I ask that the idea not be brought up again.
It would also predict that if you did a chemical reaction in the lab which produced a chiral center, you could get different enantiomeric enrichments depending on which way the stirbar in your flask was rotating.Vanadium 50 said:The idea is DOA. It would predict opposite chiralities in the nothern and southern hemispheres.
I think that you are wrong. Chiralities in the nothern and southern hemispheres were not be different!Vanadium 50 said:The idea is DOA. It would predict opposite chiralities in the nothern and southern hemispheres.
While there is some evidence that there is an advantage to homochirality, as far as I know there is nothing but speculation on why or even if the handedness on Earth is more advantageous than the opposite one.
exponent137 said:I think that you are wrong. Chiralities in the nothern and southern hemispheres were not be different!
This about influence of rotating Earth is not my theory, but of Kevin McHugh.Vanadium 50 said:I was going to respond in detail, asking you to consider whether the chirality would flip if the Earth were spinning the other way, or if it were upside down, and so on. But it's your personal theory, and you can abandon as much actual science as you would like in crafting it. Just don't expect other people to take it seriously.
Chirality in biology refers to the property of molecules to exist in two different forms that are mirror images of each other. These forms are known as enantiomers and can have different biological effects.
Chirality is important in biology because it affects the properties and functions of molecules in living organisms. Enantiomers can have different interactions with enzymes, receptors, and other molecules in the body, leading to different biological effects.
The reason for one chirality in biology is thought to be due to the origins of life on Earth. It is believed that a random event in the early stages of evolution led to the selection of one enantiomer over the other, and this preference has been passed down through generations.
Chirality plays a crucial role in drug development as the different enantiomers of a molecule can have vastly different effects on the body. It is important for scientists to understand the chirality of a drug and its potential interactions with enzymes and receptors in order to develop safe and effective treatments.
Yes, chirality can be artificially created in a laboratory through chemical synthesis. However, creating a specific enantiomer can be challenging and often requires advanced techniques. This is why many pharmaceutical companies invest in research and development to create drugs with a desired chirality.