3 ms·
"But there’s a glaring hole in this plot: ribosomes themselves are made up of proteins" Ribosomes are made up of proteins and rRNA! And the Peptidyl transferas
by julienchastang 12y ago
"But there’s a glaring hole in this plot: ribosomes themselves are made up of proteins"
Ribosomes are made up of proteins and rRNA! And the Peptidyl transferase catalytic reaction which forms peptide bonds is entirely conducted by the rRNA[1]. Proto/paleo ribosomes were probably entirely RNA in the RNA world, long ago. Dawkins alludes to this (though I cannot remember the precise language since I don't have the book in front of me now).
[1] http://en.wikipedia.org/wiki/Peptidyl_transferase http://en.wikipedia.org/wiki/Peptidyl_transferase
- Lanoteu 12y agoCatalytic RNA species have their place in the RNA world hypothesis, yes. But to suggest that rRNA itself can catalyze peptidyl-tranferase reactions without the use of ribosomal proteins in today's organisms may be far-fetched. Even the most primitive of organisms have ribosomal proteins to accompany the rRNA.
- julienchastang 12y agoFrom the wikipedia article referenced earlier: "Peptidyl transferase activity is not mediated by any ribosomal proteins but by ribosomal RNA (rRNA), a ribozyme. This RNA relic is the most significant piece of evidence supporting the RNA World hypothesis."