Dideoxy Nucleotides

by Jason Amores Sumpter
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So in our last lesson video, we mentioned that Di di Oxy nucleotides are special nucleotides that are commonly used in DNA sequencing techniques. And so here in this video, we're going to talk more about these di di oxy nucleotides now. First, it's helpful to recall from way back in our previous lesson videos when we first introduced DNA that Foss Foto di Ester bonds are the types of bonds that form between the three prime hydroxyl group or O H group, and the five prime phosphate group of two nucleotides during DNA synthesis. Now these di di oxy nucleotides are sometimes referred to as D. D N T. P S and D d Oxy nucleotides again are very special nucleotides that differ from the usual normal DNA nucleotides that a cell might use. And so these diet the oxy nucleotides, they actually contain a three prime hydrogen atom instead of containing the three prime hydroxyl group like what the normal DNA nucleotides have. And so, by replacing this three prime hydroxyl group with the three prime hydrogen atom, this actually blocks the Covalin formation of the phosphor ODs or bond, and so did the oxy nucleotides will block the formation of a fastidious or bond. And so, during the elongation step of DNA synthesis, uh, if a d d n t p is incorporated, if a diet he actually nucleotide is incorporated, uh, then the elongation during DNA synthesis will be terminated. And, uh, elongation will come to a stop if a d D NTP is included, and this is going to be very important once we get to d n a. The specifics of the DNA sequencing technique as we move forward. And so, um, of course, the elongation is going to be terminated by the incorporation of the d d NTP at the three prime end of the new d n a Strand. And so we'll be able to see this down below in our image. And so, in this example here we're looking at how diet the Oxy rival nucleotides can terminate elongation during DNA synthesis. And so, in this image at the top here and the greenish color, what we have is the regular DNA nucleotide, which is the d oxy Revo nucleotide. Uh, and this is, uh, the normal nucleotide as we covered it when we first introduced d n a way back in our previous lesson videos and what we have at the bottom here is the special DNA nucleotide that we're calling the di di oxy nucleotide Revo nucleotide, And so notice that it has the hydrogen atom at the three prime, uh, position instead of having the hydroxyl group at the three prime position. And so once again, over here on the left hand side, we have the normal deoxyribonucleic tides. Um, and what we can see is that it can the normal ones can form fossil digester bonds. And so you can see the normal one is able to form a fossil digester bond, which we have highlighted here between two different nucleotides. So this would be the faucet. So digester bond. Uh, and so the normal nucleotides can form the fossil diaspora bonds. But what's important to note is that these die deoxyribonucleic tides, the special ones over here, uh, they cannot form fossil digester bonds. And so you can see here we've got the red X to represent that the fossil dinosaur bob cannot form. And so this is going to have important implications during, uh, the elongation phase of DNA synthesis because, of course, with the normal nucleotides that we have over here. DNA synthesis will be able to proceed as normal. However, as you can see over here on the right hand side with these Di di Oxy, uh, Revo nucleotides. When there's a hydrogen atom at the three prime, Uh, and instead of a hydroxyl group, then DNA replication is going to come to a stop. It will be terminated, as we mentioned up above here. And so these die deoxyribonucleic tides are gonna help terminate, uh d n a synthesis, the elongation of DNA synthesis. And again, this is going to be important as we move forward and talk about di di oxy sequencing. So this year concludes our brief introduction to Di di Oxy nucleotides, And as we move forward, we'll be able to talk about Di di Oxy sequencing. So I'll see you all in our next video