Explain how the expression of a single gene can be quickly, efficiently, and specifically shut down at the transcriptional, posttranscriptional, and posttranslational stages through the coordinated expression of a transcriptional repressor, an miRNA, and a ubiquitin ligase.

Video transcript

Hi, everybody. Let's take a look at this practice problem together, identify the enzyme that cleaves pre M I R N A into an approximately 22 nucleotide M I R N A. Now recall that M I R N A s are micro RNA S and they are a type of small non coding RNA. They are important in gene expression control. So what enzyme produces these mature M I R N A S. As we glance at the answers, we should immediately recognize D RNA polymer rates. Now, this is an enzyme that transcribes D N A. Therefore D is incorrect options. See ribose, I'm now Ribas times are RNA molecules that can act as an enzyme and they function to catalyze bonds within nucleic acid molecules and do not cleave M I R N A. So C is also incorrect option A R I S C. This is an enzyme that's RI sc is short for RNA induced silencing complex. Now, this complex can use micro RNA S and S I or small interfere R N A S for gene regulation. It does not produce mature M I R N A. So A is also not the correct answer. So the correct answer is option B Dicer. Now, Dicer is what produces these mature M I R N A s. And just to note and connected these products of Dicer can actually be used by the enzyme R I S C for gene regulation. But for this question, the correct answer is B Dicer. Alright. Everyone, I hope you found this helpful and I'll see you soon from the next practice problem.