fragments of copied dna created on the lagging strand

Needs to get split, and then we can build another, we can build another side of the ladder on each of those two split ends. The two sides of our helix, the two DNA, the double-helix This in previous videos where we give an overview of replication, is the general idea is that Now the first thing, and we've talked about So this is the 3' end, and 3' end of it and then So this and this are the same strand, and this one, if you follow it along, if you go all the way over It all the way over here, it goes, this is the corresponding 5' end. Here the 3' and the 5' ends, and you could follow It's somewhat natural, in it's natural unreplicated form, and you could see we've labeled So here is just our of our DNA strand, and it's, you can imagine Well let's look at thisĭiagram right over here that really gives us an overview of all of the different actors. So what am I talkingĪbout with polymerase. You can't go from theģ' to the 5' direction. If you're only adding on the 3' end, then you're going from theĥ' to the 3' direction. Is you can only add nucleotides on the 3' end or you can only extend … You can only extend DNA We wouldn't be able to add going … We wouldn't be able to add going that way. So if we were talkingĪbout this right over here, we would only be able to add … We would only be able More and more nucleotides to grow a DNA strand it can only add nucleotides on the 3' end. And this is gonna be really important for understanding replication, because the DNA polymerase, the things that's adding

So this is the 3' endĪnd this is the 5' end. Parallel to each other, but they're oriented These two backbones, these two strands are What we're talking about when we talk about theĪntiparallel structure. So this is the 3', this is the 5', this is the 3', this is the 5'. Notice three, this phosphateĬonnects to a phosphate, this connects to a 3', then it connects- then we go to the 5'Ĭonnects to a phosphate. So this end is 3' and then this end is 5'. it is going, let meĭraw a little line here, this is going in the 3' to 5' direction. So this side of the ladder, you could say, it is going in the. That's the 4' carbon, and that's the 5' carbon. That's the 2' carbon, that's the 3' carbon, So we have ribose right over here, five-carbon sugar, and we can number the carbons this is the 1' carbon, Happening on the riboses that formed part of this This is a zoom-in of DNA, it's actually the zoom-in from that video, and when we talk about the 5' and 3' ends, we're referring to what's Of a quick review here, just in case you saw it but Unfamiliar to you, I encourage you to watch the video on the antiparallel structure of DNA. Of the DNA molecule, and if that is completely It, I'm gonna talk a lot about the 3' and 5' ends SBS got removed, and hydrogen bonding helo bases get together again.Ī little bit in more depth about how DNA actually copies itself, how it actually replicates, and we're gonna talk about the actual actors in the process. Then why DAN strands re-anneal? No special enzyme or protein. So, yes, you can say topoisomerase acts, but not to re-anneal DNA strands, but to untangle it. This reaction is reversible, and the phosphodiester bond re-forms as the protein leaves. You ma yay they stabilize fork and prevent from re-annealing.Ī DNA topoisomerase can be viewed as a reversible nuclease that adds itself covalently to a DNA backbone phosphate, thereby breaking a phosphodiester bond in a DNA strand. Singel strand DAN binding proteins bind tightly and cooperatively to exposed single-stranded DNA strands without covering the bases, which therefore remain available for templating. Primase catalyzes the synthesis of primer, and then DNA polymerase adds on the 3' end of the RNA primer.ĭNA helicases start unzipping DNA molecule propr to replication fork by hydrolyzing ATP and propelling themselves along the DNA strand.

On handout (11-3) of events at the fork, RNA primer is positioned. Short RNA stretch made by primase is called primer.

Fragments of copied dna created on the lagging strand