We are down to one point. So chiral-twins molecules have identical properties and are equally stable, but in nature, do we observe equal number of both twins for any particular molecule, or some molecules tend to mostly occur with just one specific chirality, for some reason?
For the alternative theorists:
- Thread starter paddoboy
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We are down to one point. So chiral-twins molecules have identical properties and are equally stable, but in nature, do we observe equal number of both twins for any particular molecule, or some molecules tend to mostly occur with just one specific chirality, for some reason?
As I have stated, several times by now, to the best of my recollection, unless the reactions are conducted on a chiral substrate or in a chiral solvent, reactions that produce chiral molecules produce both enatiomers in equal amounts.
The person who solves that problem, and does so using a scalable technique stands to make billions in the drug industry because this is one of the biggest problems facing the drug industry. Half of the reactants they put into their vats go into producing molecules that are at best useless because they are the wrong enantiomer and have no effect on our homochiral physiology. Where one enantiomer is biologically active, the other will be inactive, or react with the body differently. An example of this is Carvone - d-Carvone smells like carraway, l-carvone smells smells like spearmint. The only difference is the way the molecule is arranged around a particular carbon atom, but that changes the way it interacts with the receptors in the nose and thus the smell that is perceived.
That can not be. If both chiralities are equal they can not be selectively extinguished. The battle for resources wound not be able to target any one particular side. If something is the same, then it can not be a factor in any kind of selective "decision", like 'natural selection' is.
a.) abiogenesis was happening at many place over some extended periods of time
b.) abiogenesis happend at one place, only once, and all the life evolved from there
My answer is a.), what's yours? I do not only think it was happening all over the world and over extended periods of time, I'm saying it never ceased to happen and it's still happening even today.
Why not? Surely we should try to see if one possibility is perhaps more likely than the other, that much evidence we have, don't we?
Yes it can.
This is false in all regards.
If I have two life forms, and both life forms are dependent on some resource, but one life form depends on a resource that's ten times more common than the resource the other life form is dependent on, which do you think is going to be more successful, all other things being equal. The life form that depends on the common resource, or the life form that depends on the rare resource?
My answer is you're presenting a false dichotomy and b.) is a misrepresenation of what I actually said.
Because, at this stage, I consider such speculation pointless. The only opinion I have on the matter is that life was probably initially restricted to some environmental niche or other (for example, around black smokers) and spread rapidly outwards from there.
- "In biology, homochirality is a common property of amino acids and sugars."
http://en.wikipedia.org/wiki/Homochirality
Wikipedia says it's a pretty common thing for amino acids and sugars, to occur all in the same chiral form. Just as I foretold.
Impossible. If A is equal to B, then both A and B have 50-50% of survival. What is it, what difference do you believe there can be to selectively favor one over the other if they are equal? It does not compute. What is the same can not be different.
But Trippy's scenario wasn't equal: there was an important difference in the amount of resources available to each organism.
the simplest form of life that biology knows is the living cell.
what is represented on the site is not a living cell.
it most certainly doesn't represent the DNA centered life on this planet nor does it attempt to explain how DNA centered life could come from it.
it's a good question whether what is represented can even apply to reality.
So they are different organisms, but why would they be different and not just mirrored?
DNA is not a part of the definition. The question is whether it is a "living" thing or not. And I say that it is because it fits the description given by the definition you pointed to yourself:
1. Homeostasis
2. Organization
3. Metabolism
4. Growth
5. Adaptation
6. Response to stimuli
7. Reproduction
Does it not fit the description?
it isn't the only explanation as to how life "came to be".
no one has established abiogenesis is responsible for life
the truth about abiogenesis should be taught to our children.
my point is that science does not know how life came to be.
an RNA based "pseudo-cell" does not accurately represent life on earth.
like i said, it isn't DNA based nor does it explain how a DNA based lifeform could come from it.
i also doubt whether it meets the biological definition for life.
leopold
Wrong. Or are you arguing that viruses are not alive? They certainly evolve. What about prions? The cell is far from the simplest lifeform known.
Grumpy
As far as I know, viruses do not meet the criteria as "alive."
Only genetic transfer upon infection.
And a prion possesses neither DNA or RNA.
You think some other explanation is more plausible than abiogenesis? Which one?
wow, that DOES sound ridiculous.
hmmm . . . i wonder why NASA made sure voyager was disinfected.
i wonder why NASA made sure the LEM was disinfected.
or why the astronauts were quarantined afterwards.
yeah, "alien life" is rubbish.
in other words this is an odd statement coming from someone that thinks life can come from "nowhere".
if it can happen on earth then what is so terribly wrong with it happening elsewhere and BROUGHT here?
i submit "alien intervention" has WAY more going for it than divine inspiration.
@ leopold, referring to your Post #1615 :
Grok'd! ... Grok'd!! ... Grok'd!!!
Grok'd! ... Grok'd!! ... Grok'd!!!
it appears it's difficult to decipher between abiogenesis and " intervention "(humanity creation)
the intervention of evolution(alien's) is further down on the time line than abiogenesis.
it should not be this difficult to understand.
not necessarily true,
there's so many variables of what an IB or alien species can be.
exchemist
Valued Senior Member
But surely the problem about alien infection or seeding is that it explains nothing? Doesn't it merely kick the can down the road, so that then we would have to find a scientific explanation for how the alien life came to be, instead of the life on Earth?
It may turn out to be true, if this meteorite evidence is supplemented in the future, but that would just frustrate everybody because it would mean life first arose somewhere else, rendering the chance of finding evidence of how even more intractable for us Earthlings.
Aliens are not the same as gods. If abiogenesis is for real, then aliens are for real just as much as we are. It doesn't provide any answers in general, but we haven't really even looked for the clues, like suspicious "cut-offs" in DNA sequence where it looks like as evolution was "boosted" and it kind of "jumped" at several points in time.
exchemist
Valued Senior Member
Well nobody is talking of "aliens" here, not even primitive alien life of any kind, just of chirally biased alien biochemicals. And the problem I am talking about is the origin of that chiral bias, if it proves to be extraterrestrial. See also Trippy's remarks about chirality in quartz. I have not looked at this yet, but I do recall a hypothesis that silicate mineral substrates may have played a role in (I think) stabilising complex molecules by adsorption. Need to read further on this.
Regarding what you say about clues such as cutoffs in DNA and where it "jumped", I am not familiar with anything like this. Can you provide any references for me to read on this, or are you speculating as to what might be found if we were to look?