[Build Advice] Model Anaerobic/Aerboic Breathing?

[Anthony]

Originally Posted by sir_pudding

Why does it have to produce oxygen?

Because the OP says it produces oxygen. I am at loss for why oxygen is being produced, but it's technically possible to do.

[sir_pudding]

Originally Posted by Anthony

Because the OP says it produces oxygen.

Yes, but frankly that seems to be an error.

[David Johnston2]

Originally Posted by sir_pudding

Why does it have to produce oxygen?

Because that's what anaerobic organisms actually do? The oxygen in our atmosphere did start as the waste products of anaerobic metabolisms, after all.

[gjc8]

Originally Posted by David Johnston2

Because that's what anaerobic organisms actually do? The oxygen in our atmosphere did start as the waste products of anaerobic metabolisms, after all.

No, that's what (some) autotrophs, both aerobic and anaerobic, do. And autotrophs are reliant on an external energy source (generally sunlight, at least the ones that spit out oxygen). And they spit out oxygen in an analog of eating, not of breathing.

[sir_pudding]

Originally Posted by David Johnston2

Because that's what anaerobic organisms actually do?

They do? Can you provide a source. None of the anerobic pathways I'm aware of have O2 as a product. Iron, methane, actetate ions, sure, but oxygen? Chemically it doesn't make much sense as respiration is broadly an oxidation process.

The oxygen in our atmosphere did start as the waste products of anaerobic metabolisms, after all.

It did? Do you have a source for that, either? I think you (and possibly the OP) are confusing autrophic synthesis reactions (notably photosynthesis) with respiration.

[Flyndaran]

The absolute first photosynthetic organisms were anaerobic in the sense that they died when exposed to oxygen. But they are long gone and out-competed by more efficient forms of photosynthesis that use oxygen at times.

[sir_pudding]

Originally Posted by Flyndaran

The absolute first photosynthetic organisms were anaerobic in the sense that they died when exposed to oxygen.

Anaerobic respiration almost certainly predates aerobic respiration, yes. All organisms in the early low-oxygen atmosphere use anaerobic pathways, whether they were autotrophs or heterotrophs.

But they are long gone and out-competed by more efficient forms of photosynthesis that use oxygen at times.

Photosynthesis doesn't "use" oxygen at all, ever, and in fact because chlorophyll isn't very selective it is poisoned by oxygen (certain desert plants with lots of energy and little water have an extra pathway that strips the oxygen out, most plants don't bother). Modern photosynthetic organisms all have mitochondria and use aerobic respiration, though. You seem to be confusing photosynthesis with respiration. These are separate processes:

• Photosynthesis produces sugar and oxygen from carbon dioxide and water. It requires a lot of solar energy. It is carried out in the chloroplasts of green plants.
• Aerobic Respiration produces Carbon Dioxide and water from sugar and oxygen. It also releases a good deal of energy (that living things use to phosphorylate ADP into ATP). In basically all eukaryotes it is carried out in the mitochondria.
• Anaerobic Respiration uses a different final electron receptor than Oxygen and is much less energy efficient. These pathways (there are several) are mostly used by some prokaryotes, nowadays.
• Fermentation produces alchohol from sugar and water. It is mostly used by yeasts.

[Langy]

I think Flyndaran may have meant that they were outperformed by organisms that both used photosynthesis and occasionally used oxygen.

[sir_pudding]

Originally Posted by Langy

I think Flyndaran may have meant that they were outperformed by organisms that both used photosynthesis and occasionally used oxygen.

Obligate anaerobes got pushed into marginal environments because the photosynthetic autographs poisoned the atmosphere, sure. This doesn't mean that "anaerobic respiration has oxygen as a product", which is so far as I know utter nonsense. It doesn't even seem to meaningfully relate.

[David Johnston2]

Originally Posted by sir_pudding

Obligate anaerobes got pushed into marginal environments because the photosynthetic autographs poisoned the atmosphere, sure. This doesn't mean that "anaerobic respiration has oxygen as a product", which is so far as I know utter nonsense. It doesn't even seem to meaningfully relate.

Of course what I actually said that was oxygen was a product of anaerobic metabolisms. Which it must have been because anaerobic metabolisms were the only game in town. Of course the OP's species isn't anaerobic. They're like plants only improbably active.