Slashdot Log In
Triple Helix — Designing a New Molecule of Life
Posted by
Soulskill
on Sat Dec 06, 2008 11:22 AM
from the now-with-fifty-percent-more-helix dept.
from the now-with-fifty-percent-more-helix dept.
Anti-Globalism sends in this quote from Scientific American about attempts to synthesize molecules that function as well or better than the natural building blocks of life:
"A molecule that some researchers study in pursuit of this vision is peptide nucleic acid (PNA), which mimics the information-storing features of DNA and RNA but is built on a proteinlike backbone that is simpler and sturdier than their sugar-phosphate backbones. ... Many studies have demonstrated PNA's suitability for modifying gene expression, mostly in molecular test-tube experiments and in cell cultures. Studies in animals have begun, as has research on ways to transform PNA into drugs that can readily enter a person's cells from the bloodstream. ... Some scientists have suggested that PNAs or a very similar molecule may have formed the basis of an early kind of life at a time before proteins, DNA and RNA had evolved. Perhaps rather than creating novel life, artificial-life researchers will be re-creating our earliest ancestors."
Related Stories
This discussion has been archived.
No new comments can be posted.
The Fine Print: The following comments are owned by whoever posted them. We are not responsible for them in any way.
Full
Abbreviated
Hidden
Loading... please wait.
Sounds like razors (Score:5, Funny)
Soon we will have the "quatro helix DNA" and then 5 helixes and so on.
Re: (Score:2, Informative)
That pretty much sums it up.
Attempts to create novel "life forms" using this rather than DNA are not coming any time soon. We can't even make life forms de novo using the established DNA codons.
Re:Sounds like razors (Score:5, Funny)
Parent
Re: (Score:2)
Soon we will have the "quatro helix DNA" and then 5 helixes and so on.
That's nothing- I heard AMD are doing their own research with 8 helixes!
Er. (Score:2, Insightful)
If PNA functions "as well or better", then what exactly was the reason that RNA and DNA evolved in the first place?
Re:Er. (Score:5, Insightful)
Don't make the mistake of anthropomorphizing evolution. There is no committee that considers all possible solutions and states "This is the best one". Evolution is a case of what happens happens and what doesn't die out is what's left and so considered successful.
It is entirely possible that there are much more efficient ways for life to exist or function, but are different than the way life happened to happen here on earth. Or it could be that life DID happen that way but the methodology was not optimal for the environment at the time so the DNA/RNA based forms outlived them.
Parent
Also (Score:2, Insightful)
So what's 'better' about PNR? Well, what immediately springs to mind is that it'd be similar to amino acids. And for life, amino acids and proteins are necessary. PNR could be considered 'more primitive' in the sense that it'd be more minimal - it could reuse a lot of the chemical pathways that would need to exist for amino acids.
What's 'worse' about it? I don'
Re: (Score:2)
was not optimal for the environment at the time
Into account, that is already taken
Re: (Score:3, Funny)
So why not dump a whole lot of this newfangled triple helix stuff in the environment and wait a few billion years? Let's see who's the winner then! Will it be DNA or PNA? SMS your prediction to 999-HELIX and win a spaceship!
Re:Er. (Score:5, Informative)
That said, I agree that it seems unlikely that such a fundamental shift as switching from PNA to DNA/RNA seems unlikely to have fluked itself into existence unless there's some tradeoff in, eg, efficiency of producing the molecules, or the difference is really pretty minor after all.
Parent
Re:Er. (Score:4, Insightful)
How is "evolutionary progress" not "progress"? This is the only measuring stick I've used. If PNA had indeed existed before DNA or RNA (as the article seems to suggest), and was snuffed out, then clearly it didn't function better than RNA/DNA when it came to surviving in a particular environment, or evolving. What is the "functionality" of an organism if not survival and procreation?
Parent
Re:Er. (Score:5, Insightful)
in a particular environment, or evolving
This is the exact point i'm trying to make that you seem to be missing. Survival in a particular environment does not mean a life form is best at surviving in any environment. If there was a long enough period where the stimuli and environmental pressures involved made RNA/DNA based life the most efficient, then there would be none of the alternative life forms remaining when the pressures change.
Just because a species goes extinct does not mean that that species was not "fit for survival" at all. It simply means that the species was not fit for survival given the pressures and stimuli of the time they went extinct.
The only measuring stick that matters to evolution is procreation, you're right about that. The part people forget is everything else that happens is just rolls of the dice with no specific desired outcome. If it helps the species survive the current pressures, the trait remains. If not, it either dies out or falls recessive within the species gene pool.
Parent
Re:Er. (Score:5, Insightful)
If it helps the species survive the current pressures, the trait remains.
Oops! You mean, "If it doesn't hurt the species' survival under the current pressures, the trait remains."
Parent
Re: (Score:3, Insightful)
Re: (Score:2)
But my point is that talking about the absolut 'functionality' of an organism isn't really productive or meaningful, at least not in terms of natural selection. Evolution by natural selection is a pretty good optimization technique in isolation, but an ecosystem is immensely complex, every element changing all the time (including not just climate, but every other species in proximity and even just incidentals of geography and configuration).
Natural selection is like a hill-climbing algorithm on the
But was it ever there? (Score:3, Insightful)
The big if in your statement is "If PND had existed" perhaps it never expressed in any species and so was never around to compete.
Re:But was it ever there? (Score:5, Insightful)
I can conceive of a situation where such a molecule might actually be selected against. If the molecule were "too" stable and inhibited molecular evolution, it's quite possible that early life with essentially a "broken" system like RNA, which made events like transcription errors and insertions more likely, then it's quite possible that RNA could have won out over the technically "better" molecule simply out-evolving it.
Parent
Re: (Score:3, Insightful)
This could happen right now -- the AIDS virus has crappy reproductive fidelity. Reverse transcriptase does a lousy job of transcribing RNA to DNA so the offspring have lots of mistakes. It has a very much higher rate of mutation, as a result, than DNA transcription enzymes. So what you see is that DNA-based lifeforms evolve very slowly, and AIDS evolves very rapidly. If it managed to kill off all us humans you could (if you weren't dead) make the case that RNA is "better than" DNA because we all died.
Th
Re: (Score:2)
you did when you were wondering how PNA could have existed if it wasnt the "best".
Do not forget that time frame is everything. just because PNA didnt survive does not mean that it was less efficient period full stop end of story. All it means is that it may have been less efficient for the pressures of that period in time
We like to think of ourselves as "advanced" creatures. Think how well OUR genes would have done if we had arisen in say...the middle of an Ice age.
No trees, no tools, no sticks, tiger food.
Re:Er. (Score:5, Interesting)
PNA might function better than DNA/RNA, but its cost (resources, time to create) is higher and couldn't be afforded by the first organisms.
By your logic humans who wouldn't survive a nuclear war are less efficient than roaches that would survive it.
Just, roaches will never start a nuclear war in the first place.
Parent
Re:Er. (Score:5, Insightful)
Where did I assume that? What i'm saying is there IS no way to define a peak, since its variable dependant on the time frame and environmental pressures as to what is considered "optimal".
Parent
PNA Too stable? (Score:5, Interesting)
Perhaps PNA is too stable, so that life forms based on it couldn't evolve through mutations quickly enough to adapt to changes.
Parent
Re:PNA Too stable? (Score:5, Insightful)
An excellent point; possibly the same reason why we're stuck with bodies which break down far too quickly -- an immortal organism simply wouldn't evolve.
Parent
Re:PNA Too stable? (Score:5, Funny)
Parent
Re: (Score:3, Funny)
Freddy Mercury?
Re: (Score:3, Funny)
Nwabudike Morgan?
(but even 500 years would be nice)
Re: (Score:2)
The problem isn't just mutation but also crossover events and other more common ways to "mix and match" genetics, a more stable backbone would decrease the chance of that happening.
Re: (Score:3, Insightful)
Re:Er. (Score:5, Insightful)
Possibly because evolution requires a molecule that is not too stable.
I'm just speculating here... the basis of evolution is random changes in DNA which result in a phenotype which may confer an advantage to one individual over another. If you have an absolutely error-proof system of DNA replication, you effectively limit evolution. But you don't want too many changes at one time, which would actually be detrimental. The ideal balance is somewhere in between... and it may be that a DNA double-helix with a sugar backbone is the ideal molecule for allowing just the right frequency of random changes for evolution to progress.
Parent
Re: (Score:2)
Re:Er. (Score:5, Insightful)
"A synthetic molecule called peptide nucleic acid (PNA) combines the information-storage properties of DNA with the chemical stability of a proteinlike backbone."
I see two possible reasons PNA was not selected.
First, as others have said, it's stable. Evolution requires a bit of mutation to move forward. Out of a billion mistakes, maybe 1(or less) will cause an organism to be more 'fit.' So, you have a balancing act between errors and fitness, where too many errors reduce an organisms fitness and two few reduce it's adaptability.
Second, the protien backbone is possibly biologically expensive. There are many who believe advances in human intellegence is linked very closely with the availability of massive amounts of protein provided by cooking our food. So, the availability and neccesity of protein could be limiting factors in evolution. So any process which provides the same function with significantly less biological cost, even if slightly inferior in other ways, may be selected.
Parent
Re: (Score:3, Informative)
Except there are plenty of vegan foods that contain protein.
Here's the first google result for searching "vegan protein":
http://www.vrg.org/nutrition/protein.htm [vrg.org]
Also, IANAV, but I did know that meat was not the only source of protein.
Good (Score:2, Interesting)
Re:Good (Score:5, Funny)
Yeah sugar-phosphate is just too scary. Lets create life based on stuff we aren't made of like lead and mercury.
Parent
Triple helix... finally (Score:3, Funny)
This will be how science finally gets us to 6-asses. I am pre-ordering my 6-assed monkey right now.
But will this really be an improvement? I don't even want to think about how many razor blades will be needed to shave all those asses. They'll probably have to come out with a 12-bladed disposable razor or something...
Binding Affinity (Score:5, Informative)
IIRC, PNA had one outstanding feature: It binds to a complementary DNA strand much stronger than DNA itself (due in part to the lack of repulsion in the protein backbone. DNA's phosphate backbone is negatively charged).
Sadly, this means that two stands of PNA will bind extremely strongly to each other, and the forces required to unpair (part of the replication process) them would require different, "stronger" enzymes - so no chance of cell division, and no chance of life. (Still sounds cool though!)
Re: (Score:3, Insightful)
I don't have much of a biology background but what you say makes sense. If the chemical bonds are stronger in PNA then you have to have other higher energy state free radicals floating about to break them apart which would likely be ractive with other chemical structures in cells that are not reactive chemically with the enzymes that unzip DNA. You might have a more stable "code of life" with PNA but It might not lend itself to the complexities of a eukarotic cell.
Re: (Score:2)
I am not a bio-engineer and I'm only partially good at skydiving analogies, but I had wondered how plans for using bio-computers would function. I get how they have been using cells with inputs to control things experimentally, but if you want to use biology based memory storage there must be some way to control what is being stored. Again, might be talking out of an orifice, but wouldn't something like this lead to methods of storing bits?
Even if you could only store 256Kb per cell, that's still a lot of i
Re: (Score:3, Interesting)
Re: (Score:3, Interesting)
Re:Binding Affinity (Score:4, Interesting)
That is, do DNA-based cells exposed to PNA stop being able to reproduce themselves? (DNA unzips, PNA wiggles in and binds, everything shuts down)
Parent
Re:Binding Affinity (Score:4, Informative)
Parent
Re: (Score:2)
Wasn't this part of a movie plot? (Score:2, Funny)
Re:Wasn't this part of a movie plot? (Score:5, Insightful)
Parent
Does It Self Correct (Score:2)
As all science-accepting persons knew, when you accept Evolution by Natural Selection as the means of development of intelligent life, it up until now has required some faith because of the impression of 500,000 monkeys pounding away on typewriters, writing:
"To be or not to be, that is the ka;lija;kja"
As believers in the accumulation of complexity, we knew we were missing something. Recently, that missing piece became apparent in a behavior of certain cancers that would attack a human and then, almost mirac
rifers trilogy? (Score:2)
kinda reminds me of the writings from this guy:
http://en.wikipedia.org/wiki/Peter_watts [wikipedia.org]
Threshold protocol activated (Score:3, Funny)
what could possible go wrong (Score:2, Interesting)
This deserves a "whatcouldpossiblygowrong" tag. They will end up developing some horrible new superbug that will kill us all or create some other horrible disease, or mess something up. When dealing with these sorts of things there are unintended consequences and the results can be disasterous. Manipulating genetics is far too dangerous in my opinion, especially since organisms self reproduce. We could end up contaminating our food supply or unleashing mutants that invade the world. It has already been show
Counterargument (Score:2)
Have you watched any "reality TV?"
Cheers,
Dave