question_answer 26)

  DNA is a polymer of nucleotides which are linked to each other by 3'-5'phosphodiester bond. To prevent polymerization of nucleotides, which of the following modifications would you choose? (a) Replace purine with pyrimindines (b) Remove/Replace 3' OH group in deoxy ribose (c) Remove/Replace 2' OH group with some other group in deoxy ribose (d) Both (b) and (c)

Answer:

                  (b) The enzyme called DNA polymerase progressively adds deoxyribonucleotides to the free 3'-end of the growing polynucleotide chain so, that replication of the 3'-5' strand of the DNA molecule is continuous (growth of the new strand in 5'®3'direction). So, to prevent polymerization of nucleotides 3'OH group in deoxyribose should be replaced/removed.