3) RNA Interference

Jason Amores Sumpter
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in this video, we're going to talk about the third level of post transcription all regulation and eukaryotes, and that is RNA interference, and so are in a interference. Is commonly abbreviated as just r n A. I with a lower case, I hear, and so RNA interference or are in a I is really just the process of small non coding. RNA is blocking translation of target M RNA molecules. And so these small, non coding RNA yes, are really just short strands of RNA that have a complementary sequence to an M R N a target. And so we'll be able to see more and learn more about them down below in our image. Now, really, there are two possible scenarios that are going to turn gene expression off when it comes to RNA interference. And so the first possible scenario is M. R N A. Is going to be degraded and targeted for degradation. And then the second possible scenario is going to be that the ribosomes is going to be blocked from binding, and that's going to prevent translation. And so let's take a look at our image down below where you can see in our example, RNA interference can block ride his own binding or recruit cellular enzymes for M RNA degradation. And so, over here on the left hand side, notice that we're showing you are miniature version of the map and you can see that again. M RNA degradation and translational control is going to occur in the cytoplasm of the cell outside of the nucleus and so up here, uh, notice in this image where this image we're focusing on RNA interference or are in a I and notice that it's going to require small, non coding RNA s like this little short orange RNA, a molecule that you see at the top. And this short, small, non coding RNA is complementary to a small sequence on the m r N A itself the messenger RNA. And so there are two levels here. There is the M RNA degradation scenario, and then there is the translational control scenario. So in the M RNA degradation scenario, what happens is the small non coding RNA is going to complementary bind to the m r N a. And the mRNA is going to be degraded. It's going to be degraded by enzymes. And so the small, non coding RNA here is basically marking the mRNA for degradation. And so you can see that this enzyme over here is degrading the mRNA into small, tiny pieces. And, of course, the gene product will not be made if the mRNA is being degraded. And so this is a way of turning off the gene expression. Now, if we take a look at the translational control scenario, what happens is the M R N A. The small, non coding RNA complementary binds to the mRNA. But in this scenario, when the small, non coding RNA binds to the m r N a, um, the M r N A is not going to be degraded. Instead, the ribosomes is not going to be able to bind to the m r N A as it normally would to translate it. And so, in this scenario, the ribosomes is blocked from binding to the mRNA. And, of course, that is also going to prevent the gene product, the protein from being made, and so that is also going to be turning off gene expression. And so this here RNA interference is basically interfering with the M r n A and turning off the expression of the M r N A. And so this year concludes our introduction to RNA interference, and we'll be able to get some practice applying these concepts as we move forward in our course, So I'll see you all in our next video.