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In other words, what products synthesized by ribosomes are actual parts of ribosomes (if any)? How are they involved in their own synthesis otherwise? What is the cycle/chain of products starting with the proteins synthesized by ribosomes and actually ending with the synthesis of a ribosome?

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The most important parts of the ribosome are not made by other ribosomes - 5 rRNA (ribosomal RNA) of the ribosome actually do most of the direct work of creating the protein and are made by RNA polymerase ( a protein, but not the ribosome).

Then there are 92 ribosomal proteins, which as a rule bind to ribosomal RNA to support their structure and keep everything going. These are all made by ribosomes. They are thought to have appeared later in the evolution of the ribosome though I imagine that it would not be possible to constitute a working ribosome without each one of them.

these numbers are for the eukaryotic ribosome, the prokaryotic ribosome has 3 rRNA and 52 ribosomal protein components.

http://en.wikipedia.org/wiki/Ribosome

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Is it fair to say then, that a ribosome is really an RNA scaffold (or multiple, actually) upon which ribsomal proteins bind and collectively form active ribosome units? – leonardo Mar 3 '12 at 0:24
Any hints to articles describing the RNA-P synthesis? ... or is RNA-P synthesized by ribosomes? – pointernil Mar 3 '12 at 17:33
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leonardo that was the most amazing result of the first ribosome structures - the chemical assembly of the peptide and codon recognition was done almost entirely by the rRNA. – shigeta Mar 5 '12 at 7:51
pointernil - RNA polymerase? its totally made of protein. since it uses DNA as a substrate, it is a much more recent development. the original RNA syntesis was probably done by RNA, but to my knowledge all those genes seem to have been replaced by protein mediated functions (hope i got your question right). – shigeta Mar 5 '12 at 7:53
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@leonardo that is the prevailing hypothesis. This just out - another view of the ribosome challenging 'RNA World'. I'm not a believer here, but its an interesting idea. sciencedaily.com/releases/2012/03/120312192839.htm – shigeta Mar 13 '12 at 16:49

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