Abiogenesis

[iNow]

I rather like the way Francis Crick did this in his 1968 paper...

 

There's nothing like a forty year old paper to inform a persons questions and perspective about modern day research.

 

Way to stay fresh with your knowledge, scrappy. I salute you.

[Mokele]

Why is the genetic code universal? Why is there only one kind of life?

 

For the same reason birds lack teeth - because any previous forms are extinct.

 

And before you continue your griping about this, consider the alternative: either life formed all at once, in a single, spectacular "poof" moment, or it formed in piecemeal fashion and the previous forms are extinct.

 

Any intermediate steps, either in evolution or abiogenesis, were actual organisms or proto-organisms. The absence of a current representative of an intermediate form can only be explained by extinction, parallel evolution, or the putative form having never existed in the first place.

 

Therefore, if you accept the presence of *any* intermediate stages, and that they do not exist anymore, you have only two options, neither of which support your claims.

 

So, it seems relevant here in this discussion on the various theories on abiogensis to differentiate “The Stereochemical Theory” from “The Frozen Accident Theory,” and do this with respect to the evolution of the genetic code. I rather like the way Francis Crick did this in his 1968 paper The Origin of the Genetic Code (J. Mol. Biol. 38, pp. 369-370):

 

Something you might note: Mitochondria deviate from the "universal" code, as do Mycoplasma and Candidia. These indicate the code is not so permanently fixed. Mitochondria in particular are interesting, as they have relaxes selection pressures since they live inside other cells and only have a handful of genes.

 

Of course, the two hypotheses are also not mutually exclusive - Stereochemistry could be responsible for the original code, and Frozen Accident for its maintenance.

 

It's also worth asking how many animals have we really actually *checked* the code in, rather than just assuming it's universal. The presence of deviations (admittedly minor) in free-living organisms, including a eukaryote, suggests that there may be other deviations in the hundreds of millions of living species.

[bascule]

Why is the genetic code universal?

 

It isn't. For example, prokaryotic translation and eukaryotic translation differs.

 

Why is there only one kind of life?

 

What do you mean "why is there only one kind of life"? There are many kinds of life. There are prokaryotes and eukaryotes who operate on a sort of quantity vs quality strategy. There are six kingdoms of life.

 

Are you asking why all lifeforms use ribosomes to transcribe RNA into protein? The ostensible answer to that question is what Mokele described: "because any previous forms are extinct."

 

Lifeforms based on ribosomes outcompeted all other forms for resources and all the other forms went extinct. The last universal common ancestor of all life on earth had ribosomes, and thus all descendant forms of life did as well.

 

That said, it's not like the ribosomes found in all lifeforms are the same. There is dramatic variation in the ribosomes found in prokaryotes and eukaryotes, for example.

[scrappy]

What do you mean "why is there only one kind of life"? There are many kinds of life. There are prokaryotes and eukaryotes who operate on a sort of quantity vs quality strategy. There are six kingdoms of life.

...but all kingdoms are of the same life form. In truth, there is only one kind of life: life that encodes its genetic information on nucleic acids. Show me a life form, present or past, that uses or used different molecules to encode a different genetic information.

 

That said, it's not like the ribosomes found in all lifeforms are the same. There is dramatic variation in the ribosomes found in prokaryotes and eukaryotes, for example.

I don't care how "dramatic" those variations appear to you, they are merely variations off the same theme. Prokaryotes and eukaryotes are of the same life form and they use a universal genetic code.

[Sayonara]

Show me a life form, present or past, that uses or used different molecules to encode a different genetic information.

It won't make any difference if he can't, Scrappy.

 

A gene is the inheritable unit responsible for a trait. Whether that trait is coded for in the gene by nucleic acids or alphabetti spaghetti is beside the point.

Even if it weren't beside the point, stating that you can't conceive of anything other than the currently observed manifestation of the gene unit is an argument from incredulity.

[scrappy]

For the same reason birds lack teeth - because any previous forms are extinct.

 

And before you continue your griping about this, consider the alternative: either life formed all at once, in a single, spectacular "poof" moment, or it formed in piecemeal fashion and the previous forms are extinct.

Then I don’t suppose you rule out pink unicorns, either.

 

Something you might note: Mitochondria deviate from the "universal" code, as do Mycoplasma and Candidia. These indicate the code is not so permanently fixed. Mitochondria in particular are interesting, as they have relaxes selection pressures since they live inside other cells and only have a handful of genes.

 

It's also worth asking how many animals have we really actually *checked* the code in, rather than just assuming it's universal. The presence of deviations (admittedly minor) in free-living organisms, including a eukaryote, suggests that there may be other deviations in the hundreds of millions of living species.

What is truly remarkable here are not these rare exceptions to the universal genetic code, but the fact that there is such a code. I’d say the universal genetic code is about as universal as you can get in biology.

 

Of course, the two hypotheses are also not mutually exclusive - Stereochemistry could be responsible for the original code, and Frozen Accident for its maintenance.

Well, maybe something like that. But I would see it more as stereochemistry starting the process and the frozen accident responsible for “distilling” the genetic language—in other words, abiogenesis happened when the genetic code kicked in. Check out A. G. Cairns-Smith’ s Genetic Takeover (1982).

[Mokele]

I'm going to give you one more chance:

 

Give even ONE reference which claims that the code is REQUIRED for something to be considered 'life'.

 

You made the claim, you back it up.

[scrappy]

It won't make any difference if he can't, Scrappy.

 

A gene is the inheritable unit responsible for a trait. Whether that trait is coded for in the gene by nucleic acids or alphabetti spaghetti is beside the point.

If scientists ever discover biological traits encoded on molecules other than nucleic acids, especially on alphabetti spaghetti, this discovery would reset the calendar! It would be the biggest WOW! you ever heard of.

 

Even if it weren't beside the point, stating that you can't conceive of anything other than the currently observed manifestation of the gene unit is an argument from incredulity.

Well, yes, I can conceived of a lot of things. Give me something worth conceiving.

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I'm going to give you one more chance:

 

Give even ONE reference which claims that the code is REQUIRED for something to be considered 'life'.

 

You made the claim, you back it up.

I don't dispute your claim that "life" can happen without the genetic code. I'm only arguing that biological life can't happen without the genetic code. There could be no natural selection for uncoded "life," no way to propagate heritable generations. This is true and supported, for example, by A. G. Cairns-Smith in his book Seven Clues to the Origin of Life (1985, p. 114): "Genetic information is the only thing that can evolve through natural selection because it is the only thing that passes between generations over the long term." (That is his "First Clue," btw)

[Mokele]

Your quote only specifies "genetic information". It says nothing about it being digital. It say nothing about tRNA or codons. It doesn't even say anything about genes. This quote does NOT show why an organism which uses ribozymes for catalysis with their sequences stored on DNA, with no proteins even involved, wouldn't be 'alive'.

 

Failed. Try again.

[Sayonara]

IOW, the "code" is not dependent on the medium carrying it.

[Mokele]

I'm happy to report that scrappy will not be continuing this, or any other, argument on this site due to well-deserved application of the permanent banhammer.

[Reaper]

And so the Evil Scientific Establishment has decided to burn the heretic! Oh well, there will be other nutcases....

[iNow]

I am beginning to find that research in the area of abiogenesis is catching my interest.

 

There really doesn't seem to be a ton of research going on though. Maybe I'm searching in the wrong places, but not many scientists appear to be very interested in the subject. I know that at the university I'll be attending in the fall, there is none going on.

 

How is abiogenesis viewed by the scientific community? Is there much abiogenesis research going on in universities?

 

Seraph - Now that your thread is no longer being trolled further and further off-topic, I'm curious if you've found universities or researchers studying this area, and if you've had the opportunity to correspond with them. After all, that is what you asked about. I haven't seen you around in a while, but thought I'd check in. Perhaps you're just hanging out in the shadows... not sure.

[bascule]

Seraph - Now that your thread is no longer being trolled further and further off-topic, I'm curious if you've found universities or researchers studying this area, and if you've had the opportunity to correspond with them. After all, that is what you asked about. I haven't seen you around in a while, but thought I'd check in. Perhaps you're just hanging out in the shadows... not sure.

 

Well, there was this announced last month:

 

http://www.physorg.com/news161456485.html

 

Chemists see first building blocks to life on Earth

May 13th, 2009

 

Scientists at The University of Manchester have developed an experiment that sheds new and fascinating light on how life on Earth might have begun.

 

Prof John Sutherland, Matthew Powner and Dr Beatrice Gerland from The School of Chemistry have broken new ground by synthesising almost from scratch two of the four building blocks of RNA, which is the self-replicating molecule that many scientists believe could be the original molecule for life.

 

The researchers believe they have shown how it was possible to make all the building blocks of RNA - which can carry and transmit information from one generation to the next - from the simple chemicals that would have existed on Earth four billion years ago.

 

At this time, the Earth was like any other lifeless planet that had yet to experience the radical transformation of living and breathing creatures.

 

Prof Sutherland said: “We have made the building blocks of RNA from what was around on the early Earth and is still around in interstellar space and in the atmosphere of Saturn’s moon Titan.

 

“We haven’t yet made the RNA molecule itself but we’ve made two of the four building blocks. It suggests that making the molecule is possible.”

 

The findings are published in the latest edition of the leading science journal Nature.

[granpa]

a slightly more informative article:

http://bioenergyrus.blogspot.com/2009/05/origin-of-life-rna.html