So, in order to visualize it, in order to visualize this So we're gonna have this radio-labeled piece of DNA stuffed to this DNA fragment which it's complement. To this filter paper, it's going to anneal to So what's gonna happen is when we expose the radio-labeled DNA

Piece of this DNA fragment was actually Gene A or And let's imagine that we do have Gene A, so let's imagine that this So, let's imagine that the radio-labeled piece of DNA is this pink piece of DNA. So what we do is we're gonna take the complementary sequence to Gene A and radio-label it andĮxpose it to this filter. So, we're interested in finding out if Gene A is present in Is going to be the complement to our gene of interest. So, 'expose to radio-labeled DNA.' Now, this radio-labeled DNA Okay, so the next step, step number four that we're gonna take the filter and we're gonna expose So this is the filter and I'll just write that down over here and this over here is the gel. So now, we're gonna have aįilter with these fragments and the filter is a lot What we'll do is we'll take a filter that's basically the same size as the gel and we're gonna basically just put it right on top of the gel for a little bit and the fragments will basically transfer on to the filter. So, we want to transfer it onto a filter. And what the filter willīasically allow us to do is it allow us to visualize 'cause this gel is very flimsy.

So the next step, step number three is basically we're gonna take this gel and we're gonna transfer it to a filter. So now, we've got this gel and we've got the DNA fragments separated by size on this gel.

So, we're gonna have theseįragments separated like so. Gonna move down the gel and they're gonna basically be separated based on size and based on charge. So, let's imagine that this is the gel and we add the DNA fragments So, we're gonna take these DNA fragments and we're gonna run them on a gel. But basically, the gel electrophoresis will help us separate these DNA fragments based on size and based on charge. And I made a video on gel electrophoresis if you want to refresh, you can watch that video. So, specifically we're gonna do a gel electrophoresis, 'electrophoresis' on these DNA fragments. Now Step 2, what do we do? Well, what we're gonna do is we're gonna take all these tiny little DNA fragments and we're gonna run them on the gel. And that will result in lots of these smaller pieces of DNA. We're gonna expose it to enzymes that will basically cleave the DNA in a whole bunch of different parts. So, we got this big strand and we're gonna cut it up. So, we're gonna take this big old strand. So, 'take the DNA and cleave it.' So, let me draw that out. So Step 1, what we're gonna do is we're gonna take this DNA and we're gonna cleave this. And we'll break it up intoĪ couple of different steps. Now, in order to figure out whether or not Gene A is inside this cup, basically we have to do this process known as a Southern Blot. If it's inside of this long piece of DNA. I'm interested in Gene A and I want to see if Gene A is inside of this cup. And there's just lotsĪnd lots of those DNA and let's imagine that I'm specifically interested in one gene. So it's got just a wholeīunch of DNA inside. So let's imagine that we have a cup and it's filled with DNA. So, a Southern Blot basically allows you to visualize a specific piece of DNA that you're interested in. Gonna be talking about something known as a Southern Blot.

Application of southern blotting