Dideoxy nucleotides (ddNTPs) are used in Sanger sequencing because they have what function?

ddNTPs stop elongation once they are incorporated into a growing sequencing reaction

Dideoxy nucleotides (ddNTPs) are used in Sanger sequencing because they have what function?

Okay. So this question says, dideoxynucleotide, so these ddNTPs, are used in Sanger sequencing because they have what function? Do they add fluorescence to the DNA sequence? Do they speed up the DNA amplification? Do they stop elongation, when they're incorporated, so they stop the sequencing reaction? Or do they prevent the stalling of DNA sequencing reaction, so they don't ever allow them to stall. They just allow them to always keep going. So what do you think it is? So let's go through each answer. So the first one says, d, d, n, t, these add fluorescence to the DNA sequence. Well, no. They don't. Right? They not naturally. These nucleotides don't have natural fluorescence. Fluorescence can be added to them, but that's not the purpose of using a ddNTP. And so the answer to a just makes no sense. Now, b and d are very similar because they both refer to well, this one refers to speed and this one refers to sort of letting it continue, never letting it stop. And so, ddNTPs by themselves have nothing to do with the speed of the reaction. Right? So it's not gonna speed up DNA amplification. Speed is controlled through other proteins, and it's not going to prevent stalling because there's there's no reason for it to just, you know, there's no way mechanism of allowing these nucleotides to just make sure that DNA replication never stops or DNA sequencing never stops. So the answer, it can't be b. So the only one we have left is c, and that's the right answer. It says ddNTPs once they're incorporated, so we're doing this sequencing reaction. And the sequencing reaction pulls in a ddNTP and that stops it. And the reason it stops it is because that allows scientists to determine, you know, what nucleotide is being incorporated there, and so, therefore, what nucleotide is at that position. So the answer to this question is c. So with that, let's move on.