<prompt> A dideoxynucleotide does not contain2 3 OH group3 4 OH group4 5 OH group2 5 OH group  <response>: Dideoxy nucleotide Lacks 3 OH group also. Stop the chain elongation when they are incorporated. DNA polymerase requires 3 OH group to begin polymerisation. Use: Sanger chain termination method of DNA sequencing. Didanosine is a dideoxynucleotide used in the therapy of HIV. 