The Nucleus and its Functional Domains

ID #2422

In lecture, it was said that the "ornaments" on a tandem array are "machinery used to cut and assemble rRNA." It was also said that snoRNP's are what actually cut the 45S rRNA gene into the 5.8S, 18S, and 28S rRNA's. With that being said, would it be safe to assume that the ornaments on a tandem array are essentially the snoRNP's? Or are the ornaments and snoRNP's two totally different things?


Yes, that is a safe assumption. It also explains why the branches of the "tree" get shorter towards the base - some of the rRNA has been cut away. 
However, the ornaments can also include ribosomal proteins that will be incorporated into pre-ribosomal particles. If it helps to visualize or orient yourself, the whole "tree and ornament" region containing RNA polymerases, rRNA transcripts, ribosomal proteins, and snORNPs would be the dense fibrillar region. 

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