Uses of logical arguments in debate

No, I don’t see the problem. You just need a little to make a lot. If this weren’t the case then life would be impossible. Each of us started out as a single cell, and if we couldn’t make more ATP then we couldn’t get past a few hundred thousands cells.

Conversely, the “problem” you see is dependent on no other pathways existing in the history of life, so you run into the same problem.

This, ladies and gentlemen, is TOP creationist philosophy.

Not so oblique slurs and sarcasm add value to the conversation.

At least he didn’t start quoting Scripture at you for his evidence this time. :slightly_smiling_face:

You really do excel in irony.

By contrast, I think the idea (that information is the fundamental reality) is completely and totally absurd.

“Those who are not shocked when they first come across quantum theory cannot possibly have understood it.”
― Niels Bohr

One of our contrasting confirmation biases compels us to think that. :slightly_smiling_face:

That’s not so clever. How can you possibly have understood it, past tense, when you first come across it?

It is more likely that we have incompatible concepts of information.

Quite so, and incompatible concepts of the source of ultimate truth.

@T_aquaticus This made me laugh out loud. And everybody else is off talking about fruit.

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We could also talk about the scavenging pathway, such as NAD from nicotinamide:

@T_aquaticus

That helps. Where does nicotinamide com from. And notice the ATP.

It can be derived from diet or from breakdown of NAD. ATP is neither nictonamide or NAD. NADP is not NAD, so the de novo pathway is not autocatalytic. On top of that, NAD/P only act as proton donors which could easily be filled by other molecules. Once you have a biosynthesis pathway for a proton donor it isn’t hard to see why it could replace the activity of other proton donors. The same for phosphate donors.

@T_aquaticus Your answer is sort of along the lines of what I expected. 1. Diet 2.Alternate pathway replaced. I have a hard time with “NAD is not NADP” so their appearance together in the same pathway I find a little problematic. And here’s the other thing. ATP contributes way more that phosphate groups.

Here’s another gnarly cofactor, coA. The last 5 steps in its biosynthesis are highly conserved, from bacteria to mammals, and all but one require ATP. But not just for phosphate.

I don’t have access to the pdf to show you the figure directly. Here is a You tube that lays out the pathway is excruciatingly slow detail.
https://www.youtube.com/watch?v=KQSbyhxtW-oPantothenate plus 4 ATP plus cysteine = CoA, except one of those ATPs contributes AMP, not just phosphate. ATP features prominently in a lot of cofactors.

Now here’s where it get’s interesting. And I really want to hear people’s responses to this. I have pointed you the universal path to CoA from pantothenate (Vitamin B5) depends on ATP. Now obviously, we get pantothenate from our diet and from bacteria in our gut. I have not yet looked up the plant pathway so I can say how they make pantothenate, but in bacteria it requires another two cofactors, THF and surprise, NADPH (E coli, reference

It’s easy to say, all you need is an electron donor and a phosphate donor, an electron acceptor, a carboxyl carrier. But have a look at the structures of these gnarly cofactors. There is some serious shifting of charge going on. You would think it could have been done much more parsimoniously, and without the labyrinthine cross-referencing biosynthetic pathways (though maybe not, if they all require the same kinds of chemistry)!

Does anyone have suggestions for how biosynthesis might have been bootstrapped without these cofactors? Especially ATP, which is absolutely critical to so many functions in the cell?

I’ve read suggestions for that. We don’t know if they’re true, but yes there are suggestions for that.

@Rumraket
Please, point me in that direction!

One proposal I came across recently suggested acetyl thioesthers:
Goldford JE, Hartman H, Smith TF, Segrè D. Remnants of an Ancient Metabolism
without Phosphate. Cell. 2017 Mar 9;168(6):1126-1134.e9. DOI: 10.1016/j.cell.2017.02.001

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That isn’t autocatalysis, which is what you were talking about before. Why is it a problem that ATP is involved?

Rube Goldberg machines seem like something evolution would produce. Natural selection can only see fitness, so there is no selection for parsimonious pathways. If a labyrinthine pathway increases fitness then it is selected for.

Not off the top of my head. We may never know the earliest steps in the evolution of metabolism. Is there a deity you want to squeeze into this gap?