72% 12:51 PM bb.cortland.edu 2 of 3 4. Below is the structure of a dideoxy nucle
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72% 12:51 PM bb.cortland.edu 2 of 3 4. Below is the structure of a dideoxy nucleotide, which as you can see resembles a normal DNA nucleotide except that it has no-OH group on its 3' carbon NH ??-?-?-?-?-?- a. Is this dideoxy nucleotide contain a purine or a pyrimidine? How do you know? b. Assuming that it would base-pair correctly, could DNA polymerase add this nucleotide to a DNA strand that it was synthesizing during DNA replication? Explain. c. If DNA polymerase did add this nucleotide to a new DNA strand, could it then add another nucleotide onto the chain? Explain.Explanation / Answer
Answer a. This dideoxy nucleotide contains a purine. This can be deduced by observing the structure of the compound. A purine is a dicyclic compound and consists of a pyrimidine ring fused to an imidazole ring, which can be seen in the structure.
Answer b. Yes, DNA polymerase can add this nucleotide to the DNA strand during replication as the binding requires the bonding between the OH group of the previous nucleotide with the phosphate group of this nucleotide. As there are no problems with the phosphate group, and it is as it should be, the bonding will occur easily.
Answer c. No, another nucleotide cannot be added to the chain as no phosphodiester bond can be created based on the fact that deoxyribonucleoside triphosphates allow DNA chain synthesis to occur through a condensation reaction between the 5' phosphate of the current nucleotide with the 3' hydroxyl group of the previous nucleotide. And as the 3' hydroxyl group is not present in this nucleotide bonding is not possible.
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