[Caitlin:] Felicia, my birthday is not for weeks. You've got plenty of time to make me a card. [Felicia:] Cait, first of all, your birthday card has been done for ages. And, second of all, please don't distract me. I am on the verge of creating a brand new kind of fruit. This baby is going to fly off the shelves! [Caitlin:] You're making a fruit with wings? [Felicia:] Well, as cool as that sounds, Captain Literal -- no! This weekend I went to the farmer's market where they had all different kinds of tomatoes like red, orange, yellow... Did you even know that they have a variety called Zebra tomatoes? Zebra tomatoes! [Caitlin:] I get it, you're a produce maniac, but what does it have to do with this craft project. [Felicia:] Well, there was one variety that doesn't exist -- at least not yet. So, I'm in the process of manipulating DNA of tomatoes to fix that. [Caitlin:] I'm afraid to ask. [Felicia:] Blue! I'm making a blue tomato through cloning. [Caitlin:] That's crazy talk. [Felicia:] It should actually be pretty straightforward. Let's take a look. All I have to do is cut out the bit of DNA that codes for the tomato's red colour with these scissors. Then, I put in this piece of DNA, that codes for the blue colour trait. Then, I glue the pieces together. [Caitlin:] Where did you get the blue gene from? [Felicia:] Ah. I used PCR, which we've already learned about, to amplify the blue gene from blueberries. [Caitlin:] Oh, I get it now. This craft project is a metaphor for the process of cloning. [Felicia:] I knew you'd catch on. [Caitlin:] Okay, I'm in. Let's do it. Let's make a blue tomato. I'm not sure I'll eat it, but at least it's a good way to talk about how we can manipulate DNA. [Felicia:] Blue Bloody Marys, what's not to like?! [Caitlin:] I hadn't thought about it that way. Okay, let's do it. Let's make a blue tomato. [Felicia:] Join us this week to learn everything you've ever wanted to know about cloning on... [Both:] DNA Decoded! [Music] [Felicia:] In the last two weeks, we've learned a lot about what DNA is made of and how it's packaged in the nucleus of a cell. We've explored DNA replication and the central dogma of both transcription and translation. All of these topics help us to better understand the world and what makes us, us. Understanding these cellular processes allows scientists to manipulate DNA to increase crop yields, engineer insulin, diagnose illnesses, produce vaccines, create new medicines, and to solve murders. Remember? We identified Dr. Meyers' killer. [Caitlin:] This week, we're shifting our focus to how we can use what we know about the structure of DNA and cellular processes to manipulate DNA. Informally, this process is referred to as cloning. [Felicia:] Wait! What? Cloning, as in Dolly the sheep? [Caitlin:] Well, yes and no. Dolly was the first animal to be cloned from an adult cell. But strictly speaking, cloning just means manipulating DNA. It doesn't necessarily mean duplicating an entire organism. [Felicia:] I see. So, when scientists manipulate DNA, they usually make changes to a small fragment of DNA. Once they've modified the DNA, they use the process of cloning to make more copies. The cloned DNA fragment could be as small as a single gene. Cloning is really a fancy version of cut-and-paste. We cut the gene that we're interested in, and paste it into another section of DNA. The third step is to copy, or make multiple copies of the gene. [Caitlin:] Felicia would like to borrow a gene from blueberries and put it into tomatoes to make a hip new fruit. The blue gene is what we call our gene of interest. DNA would be a lot easier to manipulate if it were as large as a tomato but, we're talking about making changes at a molecular level. We measure the size of DNA molecules in trillions of a metre! It's hard to find a pair of scissors that are that small. [Felicia:] We use a type of molecular scissors to snip off the gene of interest. They cut DNA precisely at specific sites. The scissors you use at one site won't work at another site. So, you have to pick carefully, like you'd pick kitchen scissors or hedge clippers to do different jobs. [Caitlin:] But how are we going to get our gene of interest inside the tomato? [Felicia:] We use a circular piece of DNA as our delivery system. We'll need a piece that is relatively small, so we can easily manipulate it. It has to have sequences of DNA that will make it easy to cut using our molecular scissors. And finally, it has to be able to use the host cell's machinery to replicate itself when we insert it into a cell. Sort of like a virus does. [Caitlin:] Luckily, there's a specific type of DNA that is used by bacteria to swap genetic material back and forth. This type of DNA is called plasmid DNA. Plasmid are small, circular strands of DNA that can replicate independently. Here's a closer look. After we've glued the ends of our plasmid back together to form a circle of altered DNA, we introduce the plasmid into our organism of choice to replicate. And when it replicates, it very handily produces many copies of our gene of interest. In our next video. We'll take you through the steps in more detail. Then we can apply it to cool stuff -- like making our blue tomato! Stay tuned.
