1a) Use Restriction Enzymes

by Jason Amores Sumpter
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in this video, we're going to talk more details about step one A in the steps of DNA cloning, which is using restriction enzymes and so recall that restriction enzymes are enzymes themselves that are specifically important for cleaving or cutting the d. N. A. At these specific locations called restriction sites on the d n A. And that is going to produce sticky ends. And so we're going to define restriction sites and sticky ends down below in our text. And so restriction sites are really just defined as specific sequences of DNA where a restriction enzyme will bind and cut the DNA. And so these restriction enzymes, they don't just bind and cut to any region of the DNA. They only bind to very specific regions of the DNA and only cut very specific regions of the DNA called restriction sites. And, of course, once that DNA has been cut at the restriction site, it produces sticky ends and sticky ends are really just a single stranded d n, a overhang that is going to be produced from restriction, digestion reaction and so we can get a better feel for this down below in our image, looking at restriction enzymes and restriction sites along with sticky ends. And so notice over here on the left hand side, what we have is a specific D n a, uh, molecule here. And this DNA molecule has a very specific region called the restriction site. And this specific region is going to have a very specific DNA sequence that is going to be recognized by the restriction ends up. And the restriction enzyme is symbolized here in this image as a little pair of scissors, even though it is a complex enzyme that is going to be binding to the restriction site and cutting the restriction site. Now, when these restriction enzymes cut at the restriction site, they usually generate these sticky ends. And so they create a staggered type of cut in the d. N A. And so notice that the D. N A. Is being cut in this kind of staggered way. And when it's cut in this staggered way, it creates these overhangs, these single stranded DNA overhangs that, um, are kind of, uh, sticking out of the rest of the molecule. And so these are these sticky ends that we are referring to, and the reason that they're called sticky ends is because they can still complementary base pair to other matching sticky ends as well. Talk about moving forward in our course, but for now, this year concludes our brief lesson on Step one a. Using restriction, enzymes and how restriction Enzymes will bind and cut restriction sites to generate sticky ends and, uh, separate molecules. And so we'll be able to get some practice applying these concepts and talk more about Step one be as we move forward, so I'll see you all in our next video.