So what is life?

[bellinghman]

According to this BBC report, a virus has been recreated from scratch, using DNA fragments and the known sequence of its genome. The result was apparently indistinguishable from the natural virus, as able to infect and reproduce as its forebears.

If you think that a virus is alive, then this is a case of life having being recreated in the laboratory.

If you don't (and a form of life that can be crystallised is admittedly stretching things), then they haven't, yet.

But how long will it be before a simple bacterium can also be constructed. Yes, it's going to be a hell of a lot harder, since you will have to create all the organelles, the full running cellular machinery which isn't needed for a virus (which is 'only' DNA), but I'd not bet against it.

Comments

[bellinghman.livejournal.com]

Certainly, enzymes are of biological origin - and so, almost certainly, were the nucleotides used.

One question is - given a different virus genome, could they have synthesised that other virus using the same feedstocks and methods? I'm pretty sure the answer is yes. In which case, the PHi-X'ness of the result isn't inherent in the starting materials.

Could they start with nothing but amino acids (which can be produced by pure organic chemistry) and get to the same stage? They have 5386 bases to produce and stitch together. With enzymes - I don't think there's a real problem. Without - more difficult, simply because the enzymes already exist. Artificial enzymes? Tricky, but an enzyme is also a protein, and can (in theory) also be assembled. Getting it assembled without some other enzymes. Difficult, but somewhere along the chain of required molecules, I expect that there is something that can be built without using life-derived molecules.

(I'm assuming that nano-manipulators won't be that good, but it may be the case that they do find a way of assembling DNA that doesn't make use of traditional enzyme-based biochemistry at all - specially constructed catalysts with multiple base-splicing sites are quite plausible to me.)

As for producing a bacterium, I don't think it really matters whether they've started using life-derived materials if all the materials used have previously been created using non-life-derived materials. Not unless one has a belief in some mystical life force which may be carried by enzymes and the like. And if you're following that line of thought, then you might as well posit carbon atoms as the carrier, in which case nothing short of using nuclear transmutation to create the atoms in the first place will suffice.

[songster.livejournal.com]

given a different virus genome, could they have synthesised that other virus using the same feedstocks and methods? [...] the PHi-X'ness of the result isn't inherent in the starting materials.

Oh, agreed, no question about that.

Could they start with nothing but amino acids (which can be produced by pure organic chemistry) and get to the same stage? [...] somewhere along the chain of required molecules, I expect that there is something that can be built without using life-derived molecules.

That's where we differ, I think. Using life-derived molecules as building blocks, as I said, I'd be surprised to see a bacterium inside a decade, but almost certainly within my working lifetime. Starting from pure organic chemistry, I'd be very surprised to see it inside my lifetime. It's like trying to end up with an arch without using any support scaffolding while you build it.

As for producing a bacterium, I don't think it really matters whether they've started using life-derived materials if all the materials used have previously been created using non-life-derived materials. Not unless one has a belief in some mystical life force which may be carried by enzymes and the like.

Oh, I'm not positing anything of the sort, have no fear. No, the reason I think it would be important to be able one day to start from pure organic chemistry is because it thenmay give clues as to how it really happened during evolution, hence perhaps how common life is on other planets etc. It's also a final and necessary nail in the coffin of the designer-God hypothesis. For as long as life is only producible from life-derived materials, we're left unable to disprove the contention that "This couldn't have happened without divine intervention".

If you like, it's a distinction between mending life and creating life. Both involve making living things from non-living things, but the latter is qualitatively different.