True or false: Dideoxynucleotide sequence analysis is a template-directed method that makes use of chain terminators that stop DNA synthesis because they lack a 2'OH group.

The answer is false.

However I thought it would be true because dideoxynucleotide sequences stop DNA synthesis due to a lack of an OH group on a 2' and 3' group. What have I misunderstood?

  • $\begingroup$ you probably want to edit your question given that it's for homework...check out this link to understand how we handle homework questions on this site... biology.stackexchange.com/help/homework $\endgroup$ – Vance L Albaugh Apr 24 '16 at 21:48
  • $\begingroup$ Instead of posting here you should look up the structures of deoxy- and dideoxy-ribose, and that of the phospho-diester bond in DNA. (Learning them would be good.). Then the answer to the question will become obvious to you and you will have learnt something. $\endgroup$ – David Apr 25 '16 at 8:14

It is false, because DNA synthesis occurs via DNA polymerase,5' to 3'

By hydrolyzing activated nucleotides together. This occurs by nucleophilic attack of 3'-OH, of the last nucleotide in sequence, on alpha phosphate of a corresponding nucleotide triphosphates.

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  • $\begingroup$ You should explicitly state that the 2' OH does not matter in this case, because all DNA nucleotides are missing the 2' OH, it's not needed for DNA synthesis and wouldn't affect chain termination. $\endgroup$ – user137 Jun 24 '16 at 6:08

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