Question

All DNA polymerases have 5' to 3' polymerase activity. This means that the new nucleotides are always added to the __________. A. 5' phosphate group B. 3' phosphate group C. 5' hydroxyl group D. 3' hydroxyl group

Answer 1

D. 3' hydroxyl group

Step-by-step explanation:

The polymerization activity of DNA polymerases works in 5' to 3' direction only. This means that the DNA polymerase can add new deoxyribonucleotides to the free 3' end of the primer or existing DNA strands only. The 3' end of DNA has a free OH group that exhibits the nucleophile attack on the incoming nucleotide. The free phosphate group is present on the 5' end of a DNA strand. Therefore, DNA polymerase always adds new nucleotides to the 3' OH ends (OH= hydroxyl group).