Chicken and egg

[jake-the-peg]

Which came first - the ribosome or RNA ?

How could one evolve without the other?

[Pigletion]

RNA. This was argued a lot and ignored for many years. However, the Nobel prize for Chemistry this year was awarded base don Ribosome/RNA research.

http://www.nytimes.co.../science/08nobel.html
from above
"...the ribosome is an RNA-based machine that evolved the ability to make proteins.”

I always thought the RNA must have come first as it is simpler. What would be the function of a Ribosome if there was no RNA?

Very good question Jake-the-peg!

[Clanad]

As interesting as jtp's question is, the answer, for the time being, doesn't actually include a common understanding of the definition of RNA. The substance (for lack of a more scientific term) responsible for success in some experiments is called a ribozyme. The ribozyme is a particular kind of primitive ribonuclic acid that could reproduce at least part of its self. "...primitive RNA molecules assembled themselves randomly from building blocks in the primordial ooze and accomplished some very simple chemical chores. But as far as anyone knew, RNA couldn't do anything but carry information from DNA to ribosomes.
That changed in the early 1980's, when two biochemists, Sidney Altman and Thomas Cech, discovered independently a kind of RNA that could edit out unnecessary parts of the message it carried before delivering it to the ribosome. Since RNA - ribonucleic acid - was acting like a type of protein known as an enzyme, Cech called his discovery a ribozyme. The two were awarded the Nobel Prize for Biochemistry in 1989." (Source: Origins of Life and the RNA World: Author, Jolane Abrams, Santa Cruz Science Writers' Cabal).

Let me add that problematic to this research is the assumption of a "primordial ooze", which is whole other discussion, no?

[jake-the-peg]

Actually - come to think about it - are Ribosomes encoded in DNA / RNA ?

I presume they must be.

I guess that means that in the dim and distant past there was another method of forming proteins from RNA which would provide an "environment" so that something as complex as a ribosome could evolve.

Not sure that quote's entirely accurate Clanad. I mean the bit about RNA only acting as a messenger for RNA.

There is for example no DNA in a virus - the genetic information is entirely carried in RNA and if you Google "self replicating RNA" you'll see that it certainly can have this capability.

But there's a difference between being able to self-replicate and being able to independently fabricate the wide variety of proteins required for life.

But I would agree that terms like primordial ooze are probably a little past their sell by date now!

[Pigletion]

yes, they are the lines along which I always think about these things. Something starts simple, then combines or joins or works together etc. to form something more complex. It might then be able to interact with something else and the process continues..

I might be wrong, it just seems logical to me!

[heathfield]

Further to 'primordial ooze'...There are those who postulate that RNA may have originated in 'self-replicating clays' that created complex organic molecules. At some point these organic molecules lost their dependence on the clays and became capable of developing independently.