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04:13, 4 November 2012
my internet connection is kind of spotty, so I'm saving again
In [[eukaryote|eukaryotes]], nascent RNA transcripts must generally be processed from ''pre-mRNA'' into mature mRNA, via ''RNA processing'', before they are exported from the nucleus to be translated into proteins.
''Ribosomal RNAs'' ([[rRNA]]) are the RNA molecules that form a major component of the [[ribosome|ribosomes]]. There are three rRNAs in [[prokaryote|prokaryotes]] and four rRNAs in [[eukaryote|eukaryotes]] and [[archaea|archaeans]].
The genes encoding rRNAs are among the most highly conserved (low level of sequence variance between individuals and species) genes in any genome. As such, rRNA sequences are often used to generate very precise phylogenetic trees.
The 28S rRNA (23S rRNA in prokaryotes) is a [[ribozyme]], and is responsible for the aminoacyltransferase (polypeptide-lengthening) activity of the ribosome.
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