Let's create an alien biosphere!

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Like a graphite shell? Also 2CO→CO₂+C is reversible.

Could the heat from the hydrothermal vent trigger the reverse? If so, this could recharge the chemical "battery", providing organisms that use 2CO→CO₂+C with a continuing source of energy. In effect, they would be using the Boudouard reaction to convert the hydrothermal vent's thermal energy into chemical energy.

I mean O₂ is a relatively simple molecule. If we find an exothermic enough reaction that creates it, there's no reason they shouldn't use it.

Yes, but oxygen really wants to be reduced, so it's unlikely that a significant amount of O₂ will pop up naturally, and any substance or combination of substances that can engage in a reaction that is exothermic even though it oxidizes oxygen is probably even more unfavorable. The only realistic way to get oxygen in the atmosphere is through life creating it, there's no reason for life to create dioxygen except as a byproduct or for defense. After a bunch of thinking, I think that organsims evolving photosynthesis in order to produce carbohydrates for structural uses is more plausible in order to not have to eat prey in order to get carbohydrates for energy. However, as long as carbon monoxide stays abundant, the organisms will have no need to expel oxygen in order to produce carbohydrates. Creating lipids will be more of a challenge, but they have other potential starting points, such as methane and elemental carbon; they just also require endothermic reactions.

Also, an extinction event would probably kill a lot of microorganisms, but there isn't anything really bad about that.

The reason why I anticipate one is because one happened on Earth. Obviously, we should try to mitigate it, or at least the worst part, if possible. We could try gradually making the atmosphere more oxidizing.

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[Could the heat from the hydrothermal vent trigger the reverse? If so, this could recharge the chemical "battery", providing organisms that use 2CO→CO₂+C with a continuing source of energy. In effect, they would be using the Boudouard reaction to convert the hydrothermal vent's thermal energy into chemical energy.

I don't know how to calculate the amount of energy needed to go both ways, but I would bet that it's not a lot, so I'm going to say yes.

I mean O₂ is a relatively simple molecule. If we find an exothermic enough reaction that creates it, there's no reason they shouldn't use it.

I meant use the reaction, not the O₂ FYI.

Yes, but oxygen really wants to be reduced, so it's unlikely that a significant amount of O₂ will pop up naturally, and any substance or combination of substances that can engage in a reaction that is exothermic even though it oxidizes oxygen is probably even more unfavorable. The only realistic way to get oxygen in the atmosphere is through life creating it, there's no reason for life to create dioxygen except as a byproduct or for defense. After a bunch of thinking, I think that organsims evolving photosynthesis in order to produce carbohydrates for structural uses is more plausible in order to not have to eat prey in order to get carbohydrates for energy.

That's probably okay for softer support structures. They could maybe eat away at it for energy like placoderms ate away at their armor for minerals.

However, as long as carbon monoxide stays abundant, the organisms will have no need to expel oxygen in order to produce carbohydrates.

Wait, why is that?

Creating lipids will be more of a challenge, but they have other potential starting points, such as methane and elemental carbon; they just also require endothermic reactions.

They would need to form abiotically. Cell memebranes are made of them. (Sorry if I've said something obvious)

The reason why I anticipate one is because one happened on Earth. Obviously, we should try to mitigate it, or at least the worst part, if possible. We could try gradually making the atmosphere more oxidizing.

Perhaps we could have a leaking biological system? Maybe some microorganisms become symbiotic; one makes oxygen while the other uses it and makes whatever is needed to make the oxygen (probably CO₂). But naturally some O₂ would escape, slowly building up in the atmosphere.

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I don't know how to calculate the amount of energy needed to go both ways.

Just use Hess's law.

I meant use the reaction, not the O₂ FYI.

In order for the organisms to pick up the reaction, it would probably need to make some energy source, structural material, or other substance that the organisms could use and only release oxygen as a byproduct. Otherwise, they'd have no use for it. (Chlorox-style chemical warfare is a possibility, but it would require the organisms to develop oxygen resistance, a way to produce the oxygen, and a way to excrete the oxygen at the same time, which would be very unlikely.)

Wait, why is that?

Actually, I double-counted the oxygen initially, so they would still need to remove oxygen in order to make carbohydrates.

They would need to form abiotically. Cell memebranes are made of them. (Sorry if I've said something obvious)

Organisms today can produce their own cell membranes. Also, there's nothing that mandates that organisms on the alien planet have phospholipid membranes, although phospholipids seem well-suited for that role.

Perhaps we could have a leaking biological system? Maybe some microorganisms become symbiotic; one makes oxygen while the other uses it and makes whatever is needed to make the oxygen (probably CO₂). But naturally some O₂ would escape, slowly building up in the atmosphere.

Organisms will likely evolve to use the oxygen eventually, but I doubt that that will happen at first.

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Just use Hess's law.

Wikipedia says that it says that the amount of energy in a reaction is independent of the path taken, which is obvious.

In order for the organisms to pick up the reaction, it would probably need to make some energy source, structural material, or other substance that the organisms could use and only release oxygen as a byproduct. Otherwise, they'd have no use for it.

What do you think is the most likely possibility then? I couldn't find if we had mentioned any oxygen producing reactions.

(Chlorox-style chemical warfare is a possibility, but it would require the organisms to develop oxygen resistance, a way to produce the oxygen, and a way to excrete the oxygen at the same time, which would be very unlikely.)

Wouldn't we just need one group to use oxygen to attack/defend and any oxygen resistance would come up naturally? The excretion might be harder, but not impossible.

Actually, I double-counted the oxygen initially, so they would still need to remove oxygen in order to make carbohydrates.

I don't see where you double-counted it.

Organisms today can produce their own cell membranes. Also, there's nothing that mandates that organisms on the alien planet have phospholipid membranes, although phospholipids seem well-suited for that role.

When I looked up "molecules with hydrophobic and hydrophilic portion", I only got phospholipids. Do you know of any other molecules like that?

Organisms will likely evolve to use the oxygen eventually, but I doubt that that will happen at first.

Yeah, you're probably right. Do you have any suggestions to avoid the oxygen shock? As I said before, I don't think it's that bad.

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Wouldn't we just need one group to use oxygen to attack/defend and any oxygen resistance would come up naturally? The excretion might be harder, but not impossible.

The oxygen would poison the organism trying to wield it.

When I looked up "molecules with hydrophobic and hydrophilic portion", I only got phospholipids. Do you know of any other molecules like that?

There are other molecules like that, such as replacing the phosphate group with a sulfate group, but phospholipids are the best molecules that I know of for this purpose that I know have been produced naturally.

Yeah, you're probably right. Do you have any suggestions to avoid the oxygen shock? As I said before, I don't think it's that bad.

They could probably evolve an electron transport chain beforehand but use sulfate or another oxidizing agent instead of dioxygen.

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There are other molecules like that, such as replacing the phosphate group with a sulfate group, but phospholipids are the best molecules that I know of for this purpose that I know have been produced naturally.

Then let's just use them.

They could probably evolve an electron transport chain beforehand but use sulfate or another oxidizing agent instead of dioxygen.

So you're saying they could secrete sulfur, which is a weaker oxidising agent, before oxygen. Sounds good to me.

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So you're saying they could secrete sulfur, which is a weaker oxidising agent, before oxygen. Sounds good to me.

Sulfur wouldn't be very much of an oxidizing agent in this situation, but sulfate (and sulfuric acid and bisulfate) would be. I described how organisms near hydrothermal vents could potentially use it a few posts back.

It turns out that giant tube worms living near hydrothermal vents have bacterial symbiotes that oxidize hydrogen sulfide to sulfite then use the energy from converting sulfite to sulfate to recharge AMP into ATP and use the extra electrons to power an electron transport chain. The organisms might be able to do something like that eventually, although it will take them a while to evolve it.

Those bacteria use dissolved oxygen to convert hydrogen sulfide to sulfurous acid (which then deprotonates), but some volcanoes release sulfur dioxide, so I'm sure that some hydrothermal vents will do the same.

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Sulfur wouldn't be very much of an oxidizing agent in this situation, but sulfate (and sulfuric acid and bisulfate) would be. I described how organisms near hydrothermal vents could potentially use it a few posts back.

It turns out that giant tube worms living near hydrothermal vents have bacterial symbiotes that oxidize hydrogen sulfide to sulfite then use the energy from converting sulfite to sulfate to recharge AMP into ATP and use the extra electrons to power an electron transport chain. The organisms might be able to do something like that eventually, although it will take them a while to evolve it.

Those bacteria use dissolved oxygen to convert hydrogen sulfide to sulfurous acid (which then deprotonates), but some volcanoes release sulfur dioxide, so I'm sure that some hydrothermal vents will do the same.

If you haven't noticed by now (you probably have), my chemistry is terrible, so I'm going to ask you to do most of it. Sorry.

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If you haven't noticed by now (you probably have), my chemistry is terrible, so I'm going to ask you to do most of it. Sorry.

Sulfur dioxide can combine with water to make sulfurous acid, which can deprotonate to make bisulfite or sulfite.

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Sulfur dioxide can combine with water to make sulfurous acid, which can deprotonate to make bisulfite or sulfite.

And that makes energy?

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And that makes energy?

That doesn't make much energy, but organisms can get energy by turning sulfite into sulfate.

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That doesn't make much energy, but organisms can get energy by turning sulfite into sulfate.

So along with the reactions I listed and CO+H₂O→CO₂+H₂, what specific reaction do they do with sulfur (or its anions)?

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CO+H₂O→CO₂+H₂, what specific reaction do they do with sulfur (or its anions)?

The bacteria bind sulfite to the phosphate group in AMP, which releases two electrons, then replace the sulfate with pyrophosphate, thus recharging ATP.

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The bacteria bind sulfite to the phosphate group in AMP, which releases two electrons, then replace the sulfate with pyrophosphate, thus recharging ATP.

Ok then. Can we come up with the oxygen producing reaction now? Is there enough sulfate to ease the shock?

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Ok then. Can we come up with the oxygen producing reaction now? Is there enough sulfate to ease the shock?

The bacteria have to figure out a way to use the sulfate first.

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The bacteria have to figure out a way to use the sulfate first.

CO+H₂O→CO₂+H₂, what specific reaction do they do with sulfur (or its anions)?

The bacteria bind sulfite to the phosphate group in AMP, which releases two electrons, then replace the sulfate with pyrophosphate, thus recharging ATP.

Can't we do what you said?

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Can't we do what you said?

Yes, but the idea is that the organisms will use the same general mechanism to reduce oxygen as they use to reduce sulfate.

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Yes, but the idea is that the organisms will use the same general mechanism to reduce oxygen as they use to reduce sulfate.

What do you want sulfate to be used for?

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What do you want sulfate to be used for?

redox reactions that provide the cell with energy, e.g. H₂SO₄+CH₄→CO₂+2H₂O+H₂S (or, more likely, something like HSO₄⁻+CH₄→CO₂+2H₂O+HS⁻ or SO₄²⁻+CH₄→HCO₃⁻+OH⁻+H₂S)

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redox reactions that provide the cell with energy, e.g. H₂SO₄+CH₄→CO₂+2H₂O+H₂S (or, more likely, something like HSO₄⁻+CH₄→CO₂+2H₂O+HS⁻ or SO₄²⁻+CH₄→HCO₃⁻+OH⁻+H₂S)

Thanks you. What else do we need now?

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Thanks you. What else do we need now?

We need to make sure that there's also a fairly nice way to use oxygen instead.
2O₂+CH₄→CO₂+2H₂O
Now let's work on the photosynthetic reactions.

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We need to make sure that there's also a fairly nice way to use oxygen instead.
2O₂+CH₄→CO₂+2H₂O
Now let's work on the photosynthetic reactions.

Do we need the photosynthetic reactions to make carbohydrates?

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Do we need the photosynthetic reactions to make carbohydrates?

Yes, the plants will need to be able to remove oxygen.

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Yes, the plants will need to be able to remove oxygen.

Remove it from the carbohydrates? Also, do the carbohydrates need to be relatively complex like glucose or can they be simple?

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Remove it from the carbohydrates? Also, do the carbohydrates need to be relatively complex like glucose or can they be simple?

They'll probably complexify gradually.