Eukaryotic rrna gene organization In the nucleolus, Rna polymerase I transcribes the RNA. which usually exist in tandem repeats containing 100 or more clusters of the transcription units a nucleolus is formed around each cluster RNa polymerase iii transcribes 5s rrna genes: not in cluster with other rrNa genes its gene copy number do not coordinate with other RNa genes Primary transcript 47s, containing ETS external transcribed sequence外部转录间隔区 ITS internal transcribed sequence.部转录间隔区 NTS:non- ranscribed spacer非转录间隔区 Some rrNa genes have intronEukaryotic rRNA gene organization • In the nucleolus, RNA polymerase I transcribes the rRNA, which usually exist in tandem repeats containing 100 or more clusters of the transcription units • A nucleolus is formed around each cluster • RNA polymerase III transcribes 5S rRNA genes: not in cluster with other rRNA genes its gene copy number do not coordinate with other RNA genes; • Primary transcript 47S, containing – ETS external transcribed sequence外部转录间隔区 – ITS internal transcribed sequence内部转录间隔区 – NTS: non-transcribed spacer非转录间隔区 • Some rRNA genes have intron