in this video, we're going to talk about the formation and the breakdown of new Clague acids. And so recall from our previous lesson videos that if we want to build a polymer, then we're going to need a dehydration synthesis reaction. And so dehydration synthesis reactions are going to link individual and separate nucleotides together so that they can begin to build the new click acid polymer. Now, the Covalin bonds that link these nucleotides together are specifically referred to as Foss. Phone Die Esther Bonds and notice that we have this yellow background behind the facade Iast or bonds in the text. And that's because it links to the yellow color that we have down below and our image, which will be able to see that here shortly. Now the formation of phosphor, odious or bonds between nucleotides is going to result in the sugar phosphate backbone of the nucleic acid, and the nucleic acid backbone is going to have directionality, as we already indicated in our previous lesson videos. So we know that there's going to be a five prime end and a three prime end now here were specifically indicating that the five prime end is going to be the phosphate group end the free phosphate group, which will be able to see down below. And the three prime end is going to be the free hydroxyl group, the hydroxyl end. So let's take a look at our image down below to start to clear some of this up. So we're looking at fossil a dinosaur bond formation. And so notice on the far left hand side, we're showing you two separate nucleotide monomers here. We're showing you a sight unseen. And here we're showing you a thigh mean and which will also notice is that these are specifically deoxyribonucleic tides or DNA nucleotides. Because this position here is not containing a hydroxyl group, it has one less oxygen d oxy. And so these are DNA nucleotides and noticed that their separate over here on. So if we want to join them together so that we can start toe build a polymer DNA polymer uh, then we're going to need the dehydration synthesis reaction, which we know is used to build up polymers and the dehydration synthesis dehydrates the molecule, releasing a water molecule on, and it synthesizes a larger molecule in the process. And so notice that over here these two nucleotides are joined together via this bond that we have highlighted in yellow. And this is specifically referring to the phosphor. Oh, digester bond. And so, which will note is that there is a sugar phosphate backbone that has been formed here, where we have alternating sugar and then phosphate and then sugar and then phosphate. And so this is what we call the sugar phosphate backbone and branching off of the sugar phosphate backbone. We have the nitrogenous basis. And so once again, this sugar phosphate backbone has directionality. It has a five prime end and a three prime end. The five prime in is going to be the phosphate group end the and that has the free phosphate group. So when we take a look at our image down below, notice that the free phosphate group is over here on this end and so this will be the five prime and for that reason and then, of course, the three prime and it's gonna be the end has the free hydroxyl group. And so taking a look down below here notice that there's a hydroxyl group at this end, the opposite end And so this is going to be the three prime hydroxy will end. And so this year really concludes our introduction to the formation in the breakdown of nucleic acid polymers, and we'll be able to get some practice applying the concepts that we've learned here as we move forward in our course. So I'll see you all in our next video.