Origin Of Life

[rossmc]

Is anyone out there able to give me a brief summary of the current theories of the origin of life?

[BobbyJoeCool]

if you mean abiogenesis

 

Amino Acids (ond other things) come together to form a protien. (I'm not sure if RNA is required for that to happen.) Protien forms DNA, which then repicates itself (and more protiens) to form the first cell. Evolution takes over from there.

[rossmc]

There are various areas of research. RNA theories, clay theories, panspermia etc. I just wanted a brief synopsis of each and where it currently stands.

[Ophiolite]

It is probably safe to say that no consensus has been reached yet in this area of research.

Panspermia has undoubtedly received a boost from the variety and complexity of organic compounds detected in interstellar gas clouds, in meteorites and on comets. No one would seriously doubt that cometary impact during the heavy bombardment phase contributed significantly to pre-biotic chemistry. By that same token the emergence of life soon after, or possibly during, this phase favours an extra-terrestrial origin.

Hypotheses focusing on the roles of crystal structure, such as Cairns-Smith clay progenitor, are plausible, well argued, but wholly lacking in evidence.

The Oparin-Haldane hypothesis of the primordial soup has been largely discarded in favour of the emergence of autotrophs in subterranean locales, safe from the repeated sterilisation of large impact events.

The 'RNA World' approach seems to be still popular (I don't think anyone is still maintaining DNA was the first replicating molecule), but it has significant problems. I lean towards self-replicating polypeptides and self-catalysing metabolic loops, with cellulat bodies emerging from the tendency for lipds to form spherical mebranes in water. i.e. the first cells were almost certainly a symbiotic combination of several chemical systems that together merited the term life.

I'd be happy to address any specific questions you have, but I don't want (and I don't think you want) a twenty five page essay on the subject.

[ydoaPs]

i'm surprised no IDiots have showed up yet

[mezarashi]

i'm surprised no IDiots have showed up yet

 

Shall I represent the underrepresented then?

[BobbyJoeCool]

i'm surprised no IDiots have showed up yet

 

And what about me?

[Kleptin]

There's something that I would like clarified...

 

I know that there have been attempts to recreate cell-like...things...(They aren;t actually living right?) And that they all exhibit some traits that mimic life processes. I just wanted to know if anyone has any theories on how those non-living things (as we categorize them) crossed the line to living things. I mean, there has to be a cutoff point somewhere right? And if not one, at least a distinct set of traits that show that something is alive?

[LucidDreamer]

There's something that I would like clarified...

 

I know that there have been attempts to recreate cell-like...things...(They aren;t actually living right?) And that they all exhibit some traits that mimic life processes. I just wanted to know if anyone has any theories on how those non-living things (as we categorize them) crossed the line to living things. I mean' date=' there has to be a cutoff point somewhere right? And if not one, at least a distinct set of traits that show that something is alive?[/quote']

Metabolism

Ability to reproduce

Response to stimulus

 

These are three criteria that many biologists believe that something must have to be alive, however the definition of life is controversial and many biologists add more criteria to the three mentioned above.

[Ophiolite]

My opinion is that when we have a far more detailed understanding of the probable pathways through which life arose we will then have to recognise that the distinction between living and non-living has little meaning at a certain level. There is a gradation in complexity between the two states and where we choose to draw the line is likely to be arbritary and misleading. (It will, however, provide the material for countless Ph.D. dissertations and an impressive number of academic careers.)