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Cell Biology

Learn the toughest concepts covered in Cell Biology with step-by-step video tutorials and practice problems by world-class tutors

22. Techniques in Cell Biology

RNA interference



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Hi in this video we're gonna be talking about RNA interference. So RNA interference. It can be shortened to RNA. I it's a technique scientists can use it and they do and what they use it for is to shut off a gene. They activate a gene. So this is particularly useful if you want to know what the function of a gene is, knock it out or stop it or activate it potentially through RNA. I. And then when the sale doesn't have that gene anymore, see what happens. Does it change the phenotype? Does it change metabolism? Does this sell die? Does it grow to huge sizes? Does something change the side of skeleton? Any of these types of phenotype that you look at? You would say, okay well obviously this gene has a role in cell growth or self survival or the side of skeleton or whatever is going to happen to the cell. So if you knock out the gene you can very quickly and easily identify what that gene function is. So, RNA interference is a technique that allows scientists to knock out that gene. So how do they do it? Well they use non coding RNA. So these are our neighbors that don't create proteins they stay as RNA. And that's what their function is. So examples of these are micro RNA. S. S. I. R. N. A. S. S. H. R. N. A. S. And each one of these just acts differently in their way of how they actually inactivated gene. So how you would do this as scientists sort of put them into a cell or organism. There's a few different ways to do this which would depend on what cells you're using, what organism you're using um what RNA you're using. So there's a bunch of different techniques, each one specific for that cell organism or RNA. But they get put into that cell. And essentially these RNA sequences are complementary to some kind of D. N. A sequence. So this is the D. N. A. And this is the non coding RNA. And what happens is they actually just come in and they bind to the DNA. That they're complementary to. Right? Because they're complementary these nucleotides are gonna want to bind to that D. N. A sequence that's similar and when they bind to it this will recruit other proteins to degrade it or it'll block the expression of that gene. And when that gene cannot be expressed when it's degraded when it's inhibited it's prevented from being either transcribed or it's prevented from being translated into a protein that function is going to be inhibited. So RNA interference you put that RNA into cells it's complementary to a DNA sequence and that's going to block the expression of that gene. So when that gene is inhibited like I said before the scientists can figure out what the genes function is. And so um you can do this what I talked about before where you determine the phenotype. So when you knock out the gene does the cell grow twice its size and therefore that gene is responsible for controlling cell size. Things like that. So you can determine the phenotype when the gene is not there. But it also allows for confirmation of that. So this is a process called recovery. Or just essentially it's replacing that gene. So if you knock out the gene and the cell grows to twice its size then you should be able to put back the gene in and recover the phenotype and the cell returns to its normal size. So these types of experiments are things that scientists are doing all the time using RNA interference to identify genes function. So let's look at the example. So in this uh this is kind of an example of how our nasr processed. You may have already seen this before if you've seen some videos or you talk about it in class over how micro RNA. S. And S. RNA generally work. But essentially in the cell you start with a double stranded RNA. A. An enzyme comes in and cleaves it. It's loaded into this other complex still is double stranded and then um that gets degraded you end up with a single um RNA strand bound to the protein it needs to be bound to. And then here is the important part the important part that we talked about. We have a target sequence here. It comes in. It's binding in this case it's binding to the M. R. N. A. Some are in a bind to other RNA. Um So I'm buying two DNA just depending on how they work this case, it's M. R. N. A. Um And it's binding that complementary sequence, right? And when that complementary sequence binds, it's going to target this sequence for degradation and therefore that gene will not be expressed and allowing scientists to figure out whatever function up that gene would have normally. So with that let's move on.