DNA Polymerases

by Jason Amores Sumpter
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in this video, we're going to begin our lesson on DNA prelim races. And so it turns out that the primary enzyme that's responsible for building new DNA strands are actually these DNA prelim races. And you can actually see the function of this enzyme here in its name. And so you can see that anything that ends in A S E is going to be an enzyme, as we discussed in our previous lesson videos when we first introduced enzymes. And so these are gonna be enzymes that prelim arise or build d n A. And so DNA polymerase. Is there gonna be the primary ends? I'm responsible for building new strands of DNA. Now, organisms tend to contain multiple types of DNA prelim races, and these different types of DNA prelim races will have slightly different functions and moving forward. We're not going to talk about all of the different types of DNA prelim races were on. Lee going to focus on the most important DNA polymerase is involved directly with DNA replication. Now, new DNA strands that are built by these DNA prelim races are always going to be built in the same direction from the five prime end of the DNA molecule to the three prime end of the DNA molecule. And so these DNA, new DNA strands always being built from their five prime into the three prime and or direction eyes going to be something that's consistent with all DNA Polymerase is. And so the new DNA strands are always going to be elongating from its free three prime hydroxyl group, or O H group. And so recall from our previous awesome videos that the three prime end of the DNA strands has the free hydroxyl group, or O H group. And that is what's required to elongate the DNA strand. And we'll talk Maura about this requirement in our next lesson video. And so what you'll notice is down below. Over here, we're showing you this image, and this image is basically a little cartoon to help you remember that DNA. New DNA strands are always elongated from five prime to three prime. And so notice that this guy over here is the boss and he's saying, Hey, Polly or polyamorous, can you work an extra shift today? And the worker over here? The DNA polymerase, the saying boss, you know, I only work from five prime to three prime. I don't work any other shifts. And so hopefully this little, uh, creative image here can help you remember that new DNA strands are always built from five prime to three prime and never in the opposite direction from three prime to five prime. And so to remind you, a little bit of DNA structure here, remember, the DNA structure consists of these two strands of nucleotides that are anti parallel with with respect to each other. They go in opposite directions in terms of their five prime and three prime ends. And so notice that the five prime end is gonna have a free phosphate group for each of them on the three prime end has the free hydroxyl group, and it's the free hydroxyl group that is required to elongate new DNA strands. And so the new DNA strands can Onley be built in this direction from five prime to three prime. And so this year concludes our brief introduction to DNA prelim races and will continue to talk Maura about DNA prelim races and their requirements as we move forward in our course. So I'll see you all in our next video