Transcription of Messenger RNA (mRNA) from DNA
In this lesson, you will gain a thorough understanding of how transcription works. We will investigate how DNA is transcribed into RNA with the help of a promoter and RNA polymerase. Learn the purpose of messenger RNA and explore the three phases of transcription.
Introduction to Transcription
Everyone knows that DNA contains the instructions for living things. But if you've ever been confused about how DNA actually turns into a living creature, then you're not alone. Most people, even scientists, get overwhelmed at the details involved in all the steps of the central dogma. The central dogma describes the entire flow of genetic information from DNA to RNA to the final product, a protein.
To simplify it all in my head, I think of it like I'm following a recipe. DNA is like the master cookbook and RNA is like the card that I copy a recipe onto. I imagine that I have to make a recipe card because my mom owns the cookbook, and I can't take it with me. The cookbook is similar to DNA, which lives inside the cell's nucleus and can't be taken out. So DNA has to be copied into RNA, which can be taken outside the nucleus.
Why do we need to take genetic information out of the nucleus? It's because we're going to use it to make a protein, which we can only do in the cytoplasm. The cytoplasm contains all the machinery, or the equipment, that is used to make the proteins. It's just like how my kitchen contains all the equipment for cooking my recipe. If I'm going to make my food inside my kitchen, then I need my recipe card. If we're going to make proteins in the cytoplasm, then we need the genetic recipe. That recipe comes in the form of RNA.
In this lesson, we're only going to be talking about transcription. That means we won't be getting through the entire central dogma. We'll only get to the point where we end up with RNA. In order to investigate the steps involved, we'll have to take a look at some close-up images that show how all of the molecules are arranged.
Sometimes in biology, when you're learning the tiny details, it's easy to lose sight of the big picture. You may begin to wonder exactly where we are in the context of a cell. But remember that transcription starts with DNA, and DNA lives in the nucleus. So throughout this entire lesson, keep in mind that all of it happens inside the nucleus of a cell