 Transcription, we're gonna take a piece of DNA and transcribe the information in that DNA and use that information to build a molecule of messenger RNA. I love this visual of the process because it provides you context. This whole thing is in the nucleus and does this look familiar? Who's this guy? Who is this guy? That's a chromosome. And chromosomes, and we talked about this last time, remember chromosomes are just wound up pieces of DNA. So you can unwind your chromosome and in fact, you must unwind your chromosome if you're going to make a copy of a piece of it in the form and turn it into messenger RNA. So let's unwind this chromosome and you can see this string of DNA super stringy but it starts to, you start to be able to see that oh, it actually is a double helix. And then you can see that, oh my goodness, we're not making messenger RNA from the whole thing. We're making messenger RNA just from a little part of it. Now, the part that you actually code from, and this is interesting, it's called the template strand. So you notice that we're creating our RNA transcript, our copy of the DNA using the template strand of the DNA molecule. So the first thing that happens is we have transcription factors. That took me a long time to write that out. Transcription factors first bind to the DNA and open it up. In our, in DNA replication, we had, we named a bunch of enzymes that do the work. I think we're happy that in transcription, they just call all those things transcription factors and that's awesome. Someday, if you wanna go learn all the names of the transcription factors, knock yourself out and then you can send me a message and say, I learned them all and then I'll be like, dude, teach me. Not today, we're just gonna group them into a big pile. They identify the gene that is that we need. They're going to, they're like, dude, we are going to help you express the information in this gene. We're gonna help you take the DNA and turn it into the protein that it codes for. The transcription factors come in. They, I don't know, they start, they bind to a region called the promoter region. So the transcription, the transcription factors come in and bind to promoter region. And that promoter region says start here. So it's a really important place of regulation. We can actually enhance the activity of a promoter and cause more mRNA to be produced or we can say be quiet promoter region and de-hance, decrease, whatever, the expression of that gene by impacting that promoter region. All those transcription factors come in. They bind to the promoter region and then RNA polymerase comes in. And just like DNA polymerase, RNA polymerase can only build new molecules in the five prime to three prime direction. What does that tell you? That tells you that this direction, cause we're building this direction, do you agree with that? This has to be, do you agree, my five prime end of my template. I don't know, can you see that? Is it too small? You see, I just said five prime on this end of my messenger RNA transcript to three prime on this end. What does that tell you? What are you gonna tell me about the template strand of DNA? Well, if it's five prime on that and this must be your three prime end of the template strand and down here must be the five prime end of the template strand. Directional information that's just helpful for knowing which direction, like how this RNA polymerase is gonna get the job done. Notice RNA polymerase is gonna come in. Transcription factors are gonna say, hey, this is the promoter region. RNA polymerase comes in and says, I got this. I can make a messenger RNA string all day long. Eventually it will reach, watch this. Number two, because I have room down there. You can see that, right? Transcription when RNA polymerase reaches polymerase reaches the termination sequence. I fit it all in there. It's easy. We're just going along just like DNA replication except we're using RNA nucleotides and we cruise along from the promoter region to the termination sequence. When the RNA polymerase reaches the termination sequence, it falls off and says, awesome, we're done. And that's it. That's the process of transcription. Glory days, do you feel like that was too easy? Well, your RNA, don't worry, it is that easy. We're done. But the RNA transcript has to be modified before it can head out into, before it's done. I like to think of it as like getting its fancy outfit before heading to the cytoplasm for the most exciting part of its world. There are several things that have to happen before this mRNA is ready to go. I'm gonna go ahead and add the M in front of it. First, we are going to take out, we're going to splice out sections and this is so weird. We take the whole gene, get a copy of the whole thing and then something tells someone to splice out chunks of the messenger RNA called introns. Splice out chunks of mRNA and those things are called introns. I think you'll see in a second how we're gonna remember the introns because this leaves exons that are what, taped together, connected, bonded, bonded. They're not taped together. It would be nice if there was like a sketch tape in every single cell. Nevermind, that would not be nice. You would not like that. So imagine this. We take out these random chunks. Sometimes there's like 70 chunks that we take out and then what's left are all these like splintered pieces of messenger RNA and we glue them back together again. Not gonna be hard, right? Like think about ligase was our enzyme that fixed the Okazaki fragments. I'm sure there's some enzyme that is doing that kind of work for splicing or putting back together the exons. As I'm saying this, I just need to say this out loud. I'm not sure splice is the right word to use. I think of splice as cutting but I also think of it as putting things back together again so I don't know what is the best, what is the right word? We're going to cut out. Let's just make sure you know what I mean. We're gonna cut out the chunks of introns and we're going to bond back together, tape back together the exons to get a strand, one complete mRNA strand of exons. Here's how I remember it. Exons exit the nucleus. Exons exit. It's one of those pairs of words where if you just tell me intron, I can't remember what it is until I remember exons. Oh yeah, those are the guys that exit the nucleus. I guess the introns stay in the nucleus because they are not, they don't get to go to the party, sorry. And we're still not done because the last part, we need some clothes. So we're gonna put on a five prime cap burial. It's called a five prime cap and of course I think of it as like an awesome hat that the mRNA puts on before it's ready to go. And you can't go to the party in just a hat. You have to take a poly A for adenine, poly many adenines, a long string of adenines, a poly A tail. You gotta have your poly A tail for the party. We add the poly A tail and the five prime cap and now we have a completed messenger RNA molecule that is ready to go to the ribosome. Shall we see what is going to happen next with this blinged out messenger RNA? Let's do.