The Nucleus and its Functional Domains

ID #2358

What's the point of the tandem arrays found on the genes that code for the 5S, 5.8S, 18S, and 28S genes? Does it just allow for more rRNA's to be made at a given moment in time?

Tandem arrays definitely allow a cell to make A LOT of rRNA. Actively growing cells have 5-10 million ribosomes, so it is imperative that a cell makes as much rRNA as it can. Having all of the rRNA genes in tandem arrays means that the machinery necessary to synthesize rRNA can be brought together (along with the tandem arrays) in the nucleolus. A cell can more efficiently make rRNA if all of the genes are together, since as soon as transcription factors or RNA Pol I are done with transcription of one gene, they can immediately start transcribing the next gene. 

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