NationStates Jolt Archive

I've been doing a bit of looking for some stuff related some ideas on exobiology and came across some intruiging ideas for alternative non DNA based biologies, and one that I've had wandering in the back of my mind.

I'm reaching the extremes of my college level biology and self-education here, so a bit of help would be appreciated.

Questions:
1) Could "artificial" nucleic acids such as PNA, GNA, or TNA possibly exist in an exo-system and be a viable alternative to DNA?
2) Since a triple helix structure seems to be problematic, would a hexagonal (helical?) structure work?

Nope, not one here.

I've always wondered about replacing carbon with silicon though. I'm sure there's someone who can explain why that wouldn't work.

I think maybe Dempublicents (sp?) is involved in that field. There was a thread about university undergrad/masters degrees a while back so you could have a look in there for someone.

I've always wondered about replacing carbon with silicon though. I'm sure there's someone who can explain why that wouldn't work.

Actually, silicon is one of the most, if not the most, promising alternative biochemistries. Silicon's position right above carbon in the periodic table means that it shares a lot of properties with its sister non-metal and can form similar compounds which makes it a very feasible alternative basis for life in the universe. Of course, silicon-based life would still be radically different from carbon-based life like we have on Earth, but in terms of feasibility it's possible that extraterrestrial life would be silicon-based as opposed to carbon-based in environments where carbon compounds are incapable of forming or forming properly.

Now, in competition, carbon-based life would win out, but on a planet where carbon-based life is at a disadvantage, silicon-based life is certainly a possibility. And far more beautiful, IMO, but that's solely my opinion.

Actually, silicon is one of the most, if not the most, promising alternative biochemistries. Silicon's position right above carbon in the periodic table means that it shares a lot of properties with its sister non-metal and can form similar compounds which makes it a very feasible alternative basis for life in the universe. Of course, silicon-based life would still be radically different from carbon-based life like we have on Earth, but in terms of feasibility it's possible that extraterrestrial life would be silicon-based as opposed to carbon-based in environments where carbon compounds are incapable of forming or forming properly.

Now, in competition, carbon-based life would win out, but on a planet where carbon-based life is at a disadvantage, silicon-based life is certainly a possibility. And far more beautiful, IMO, but that's solely my opinion.

What would they breathe? If carbon-based organisms use oxygen...

Silicon dioxide can't be the analogue to carbon dioxide - it's not a gas (unless these creatures are living above the temperature of molten glass).

What would they breathe? If carbon-based organisms use oxygen...

Silicon dioxide can't be the analogue to carbon dioxide - it's not a gas (unless these creatures are living above the temperature of molten glass).

They would have to either be anerobic or capable of surviving those very high temperatures, for example on a hot Jupiter or other high-temperature gas giants. In addition, they would have to exist in an environment high in compounds like sulfuric acid in order for the silicon-based compounds to be more stable than carbon-based ones.

Simply put, the places where silicon-based life is possible are not going to have carbon-based life.

Surface of Venus? High temp, high pressure, high in sulfuric acid?

Possibly, especially considering that some silicon compounds also contain carbon, and there's a ton of CO2 available in the atmosphere. However, I don't know if silicon-based organisms could survive the surface temperatures and pressure.

They would have to either be anerobic or capable of surviving those very high temperatures, for example on a hot Jupiter or other high-temperature gas giants. In addition, they would have to exist in an environment high in compounds like sulfuric acid in order for the silicon-based compounds to be more stable than carbon-based ones.

Simply put, the places where silicon-based life is possible are not going to have carbon-based life.

Surface of Venus? High temp, high pressure, high in sulfuric acid?

I think maybe Dempublicents (sp?) is involved in that field. There was a thread about university undergrad/masters degrees a while back so you could have a look in there for someone.

Yeah. Dem, and isn't Bottle doing something similar?

What would they breathe? If carbon-based organisms use oxygen...

Silicon dioxide can't be the analogue to carbon dioxide - it's not a gas (unless these creatures are living above the temperature of molten glass).

Doesn't have to be excreted as a gas does it? "Breath" in O2 gas and excrete SiO2. Might have a life form that literaly shits bricks. ;) (A fine powdered sand would be more likely though, I expect.)

Surface of Venus? High temp, high pressure, high in sulfuric acid?

The iron-sulfur world theory?

Anywho, we're veering off from the OP.

By the lack of answers actually adressing the OP questions, I'll assume ya'll don't know, and will thus wait for somebody who does. ;)

Possibly, especially considering that some silicon compounds also contain carbon, and there's a ton of CO2 available in the atmosphere. However, I don't know if silicon-based organisms could survive the surface temperatures and pressure.

Surface of Venus? High temp, high pressure, high in sulfuric acid?

The bigger question then becomes is there a sufficient amount of silicon available to support the formation of organic structures concentrated in a given region. I mean, it's one thing to develop a basic "organism" based on a silicon backbone, but for that to occur naturally somewhere there'd have to be a sufficient amount of it, much like how we need a sufficient amount of carbon in the environment to sustain ourselves.

Granted for micro-organisms, a significantly smaller amount of is necessary, but those organisms to evolve to something more complex, you'd probably need quite a bit.


Of course, I'm not a molecular biologist, so you'll probably have to wait til Bottle gets on to either tell us that what I'm saying makes sense or mercilessly rip it to shreds and leave me crying.

The iron-sulfur world theory?

Don't know how pressure would play into that theory. I thought that theory was to explain Earth's own development. Was it not specific to conditions here? Can it be applied to a high pressure atmosphere? Maybe I am asking a stupid question here. Just an amature when it comes to these things.

Anywho, we're veering off from the OP.

By the lack of answers actually adressing the OP questions, I'll assume ya'll don't know, and will thus wait for somebody who does. ;)

Good luck with that. You're talking about finding someone well-versed in molecular modeling and studying things that are (at least currently) only in the realm of pure speculation. Even most biochemists/molecular biologists wouldn't be able to tell you with any certainty whether alternate forms of nucleic acids could be the basis for lifeforms.

There's probably been more modeling done on the various possible helical structures, but I'm not familiar with that kind of work.

The only person I've seen on NSG who claimed to be a molecular biologist was Bruarong, and his viewpoint seems to be that there are no natural processes that can result in any type of nucleic acid-based lifeforms.

The only person I've seen on NSG who claimed to be a molecular biologist was Bruarong, and his viewpoint seems to be that there are no natural processes that can result in any type of nucleic acid-based lifeforms.

:confused: aren't we nucleic acid-based lifeforms?

:confused: aren't we nucleic acid-based lifeforms?

He was a Creationist.

:confused: aren't we nucleic acid-based lifeforms?

Yup.

Good luck with that. You're talking about finding someone well-versed in molecular modeling and studying things that are (at least currently) only in the realm of pure speculation. Even most biochemists/molecular biologists wouldn't be able to tell you with any certainty whether alternate forms of nucleic acids could be the basis for lifeforms.

There's probably been more modeling done on the various possible helical structures, but I'm not familiar with that kind of work.

The only person I've seen on NSG who claimed to be a molecular biologist was Bruarong, and his viewpoint seems to be that there are no natural processes that can result in any type of nucleic acid-based lifeforms.

Heh. Well, I wan't actually looking for more than a "yes it's plausable" or "no, it just can't work."

Sice no-one's canned it, I'll take that as a go ahead for some of my ideas.

My last idea for an alternate gene structure - triple helical - got shot down quickly and effectively. That this wasn't auto-killed makes it at least thoretically plausable, I hope. :)